Composition containing body activated fragrance for contacting the skin and method of use
This application is a Continuation-in-Part application of application Ser. No. 07/948,510, now U.S. Pat. No. 5,378,468 filed Sep. 22, 1992, the contents of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to compositions, particularly compositions for contacting the skin (for example, skin care compositions or personal care compositions), for producing fragrances. More particularly, the present invention relates to such compositions for contacting the skin, wherein the fragrance is formed (e.g., is released from a compound forming a component of the composition) after application of the composition to the skin (that is, body activated fragrances). 
     It has been desired to provide personal care or skin care products which have components that produce a low level of odor, or are odorless, prior to application to the skin, but which components produce compounds that are pleasant smelling (that is, provides a fragrance) after application to the skin (that is, delayed release of the fragrance). It is desired to provide deodorant or antiperspirant stick products, hand lotions, baby lotions, baby powders, ointments, foot products, facial cleansers, body wipes, facial makeups, colognes, after-shave lotions and/or shaving cream having such components. It is also desired to provide personal care or skin care products (particularly, a deodorant or antiperspirant stick product) that are clear or transparent, and have fragrancing components that, prior to application to the skin (e.g., application to the axillary regions), have a low degree of odor or are odorless, but become pleasant smelling after application. 
     Solid, transparent, gelled antiperspirant compositions, containing one or more acidic reacting antiperspirant compounds, are known. Note each of U.S. Pat. No. 4,154,816 to Roehl, et al., and U.S. Pat. No. 4,720,381 to Schamper, et al., for example, the contents of each of which are incorporated herein by reference in their entirety. Each of these U.S. patents discloses solid, transparent or clear, antiperspirant gelled stick compositions including an antiperspirant metal compound (such as aluminum chlorohydrate), and alcohols (both monohydric and polyhydric alcohols), with sorbitol dibenzyl ether (DBMSA) utilized as a gelling agent. Such antiperspirant sticks gelled with DBMSA as the gelling agent are utilized as an alkaline or neutral media, but not as an acidic media, since even in the presence of small amounts of water DBMSA hydrolyzes in an acidic medium or will react with a reactive alcohol to form a different acetal. Such antiperspirant stick compositions containing DBMSA as the gelling agent are also known to include conventional fragrances, which begin volatilizing at least as soon as the product is formed. 
     There are also known antiperspirant sticks consisting largely of gelled alcoholic solutions of antiperspirant compounds, with the gelling agent being a sodium salt of a higher fatty acid, like sodium stearate. However, such sticks cannot contain the usual antiperspirant compounds, because the acidic reaction of these usual antiperspirant compounds causes decomposition of the soap. To avoid this defect, alkaline reacting antiperspirant compounds were developed, like aluminum hydroxy chloride-sodium lactate; but these alkaline reacting antiperspirant compounds suffer from a disadvantage of having a poor antiperspirant effect. 
     It is also known to delay release of a fragrance from a composition by methods such as micro-encapsulation of the fragrance substance. However, a desired objective of a clear, transparent aqueous-glycol based deodorant stick cannot be obtained using such conventional methods of achieving delayed release of fragrances, including micro-encapsulation. For example, standard methods of micro-encapsulating a fragrance oil in a water-soluble coating system will not work utilizing an aqueous-glycol base, since the water in the deodorant stick base dissolves the protective coating and prematurely releases the fragrance. Thus, water-soluble micro-capsules are not compatible with water/glycol based formulations. Furthermore, a water-insensitive coating or micro-capsule, which is compatible with water/glycol based formulations (such as pH-sensitive or heat-sensitive micro- capsules), is not soluble in the water/glycol formula and must therefore be used as a suspension of the solid, micro-encapsulated fragrance in the liquid formula. As can be appreciated, suspensions of solids in clear liquids result in a formula which loses its transparent properties; suspensions are, at best, translucent, and cannot be absolutely clear. 
     Perfume compositions containing an acetal compound as the fragrancing substance are known. Thus, U.S. Pat. No. 4,424,146 to Willis, et al. discloses perfume compositions containing acetaldehyde ethyl dihydrolinalyl (6,7-dihydrolinalyl) acetal, the acetal differing from analogous compounds in both odor quality and strength. This patent discloses that addition of the described acetal to various perfume compositions imparts a greener, more lemony and floral character to the original product. 
     U.S. Pat. No. 3,751,486 to Schleppnik, et al. discloses specific alkyl-substituted unsaturated acetals, useful in preparation and formulation of fragrance compositions such as perfumes and perfumed products due to the pleasing green, floral and woody aromas of the unsaturated acetals. This patent discloses that the acetals described therein have utility in cosmetic, detergent and bar soap formulations. 
     Neither of U.S. Pat. No. 4,424,146 or No. 3,751,486 discloses that the described compounds can be utilized for delayed release of fragrance, or any mechanism for delayed release of fragrance upon application of, e.g., perfume compositions to the body; and these U.S. Patents do not disclose use of the stated fragrance compounds in clear products (in particular, clear deodorant or antiperspirant stick products). 
     U.S. Patent No. 3,479,297 to Rutzen, et al. discloses a room deodorant consisting of 60%-80% by weight propellant; 20%-40% by weight solvent and 0.5%-5% by weight active ingredient, the active ingredient being a cyclic acetal or ketal of a monounsaturated aldehyde or ketone having at least 3 carbon atoms and an aliphatic alcohol, the aliphatic alcohol being a 1,2-diol or 1,3-diol having 8-24 carbon atoms. This patent discloses that the cyclic acetal or ketal active ingredient is essentially odorless, but reacts within short periods of time with odiferous substances present in a room to form complexes neutral in odor, the active ingredients being sufficiently stable to retain their effectiveness over a comparatively long period of time. 
     U.S. Pat. No. 3,479,297 discloses room deodorants (not body and/or underarm deodorants or other personal care or skin care compositions) containing specific acetals or ketals which react with noxious substances. Such disclosure does not describe compounds which are odorless or of a low level of odor when applied (e.g., when applied to skin) and which are converted into pleasant smelling substances after application. 
     Accordingly, it is still desired to provide compositions (e.g., personal care or skin care products) having a delayed release of fragrance, especially a clear stick deodorant or antiperspirant product containing components for providing a fragrance, so as to achieve a delayed release of fragrance. It is particularly desired to provide such product wherein the fragrance is released after contact of the composition with skin (that is, a body activated fragrance). 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide a composition (e.g., a personal care product (such as a deodorant or antiperspirant for axillary use or other personal care product), or skin care product, to contact the skin), having delayed release of fragrance (release of fragrance after application of the composition), and method of using such composition. 
     It is a further object of the present invention to provide a personal care or skin care product having delayed release of fragrance, wherein the release of fragrance does not occur until after contact with the skin (that is, wherein the fragrance is activated by the skin), and method of using such product. 
     It is a still further object of the present invention to provide a personal care product or skin care product, in the form of a solution, powder, lotion, cream or other emulsion, or gelled stick (useful in, for example, underarm deodorants or antiperspirants or other deodorants contacting the body, or in hand lotions, baby powders, baby lotions, ointments, foot products, facial cleansers, body wipes, facial make-up, colognes, after-shave lotions and shaving creams), having at least one fragrancing component that is odorless or of a low level of odor prior to application to the human skin, but which changes into a pleasant smelling substance (that is, which changes into a compound having a strong aroma) when in contact with the human skin. 
     It is a still further object of the present invention to provide a personal care or skin care product, including a vehicle such that the product is useful in liquid roll-ons, sprays, aerosols and cream products applied to the human skin, having at least one fragrancing component that is odorless or of a low level of odor when applied, but which changes into a pleasant smelling substance when in contact with the skin. 
     It is a still further object of the present invention to provide a transparent (e.g., clear) deodorant or antiperspirant stick product with a delayed release of fragrance, the substance providing the fragrance being odorless or of a low level of odor prior to application but which changes into a pleasant smelling substance in contact with the human skin. 
     The present invention is in part based upon the recognition by applicants that human skin exhibits a &#34;buffer capacity&#34; which vigorously maintains a constant pH value. This buffer capacity is referred to as &#34;the acid mantle&#34;. Human skin acts rapidly to neutralize acidic or alkaline insults outside this constant pH value. 
     Application of a high pH soap to the skin is an example of an alkaline insult. A soap-based deodorant stick, which independently exhibits a pH of 9.5-10, is almost immediately neutralized after application to the skin by the &#34;acid mantle&#34; of the skin, to a pH of 8.2-8.3. Within seven hours of application, underarm (axillary) skin pH at the site of application is virtually restored to its original value of pH=5.5-7.0, due to the aforementioned buffer capacity of the skin. 
     Utilizing this recognition of the &#34;buffer capacity&#34; of the skin, applicants incorporate in a skin contact composition at least one component (&#34;potential fragrance&#34;) which maintains its integrity at a pH above about 8.0 and which does not release fragrance at this alkaline pH, but which begins to lose its integrity as the pH lowers to a pH of 8.0 or below and releases fragrance as skin pH returns to a normal, original (prior to application of the composition) value. Desirably, the potential fragrance retains its integrity (does not release fragrance) at a pH above 7.5, but begins to lose its integrity at a pH of 7.5 and below to release fragrance. 
     Thus, applicants incorporate, in their skin care product, various components (molecules) which are chemically stable and practically odorless in an environment having a pH of 9.5-10 (for example, the environment of the aqueous/glycol soap-based deodorant stick), but which begin to hydrolyze at a pH of 8 and below (desirably, at a pH of 7.5 and below) to release the odorous portion of the molecule. Therefore, in a, e.g., deodorant base of pH=9.5-10, the component is a &#34;potential fragrance&#34;, capable of forming a compound having a pleasant scent (e.g., upon lowering of the pH), yet itself being stable and relatively odorless. Upon application to the skin, as the pH of the environment of the component lowers to a pH of 8 or less (desirably a pH of 7.5 or less), and as the skin pH lowers towards 5.5-7.0, fragrance is released due to hydrolysis of the molecule releasing the odorous portion of the molecule; and as the skin pH lowers towards 5.5-7.0, more and more fragrance is released (e.g., over a roughly 7-12 hour period). 
     Accordingly, the present invention provides a composition, and method of using such composition, having a potential fragrance, the potential fragrance only being activated after application of the composition to, e.g., the skin. The composition is an alkaline composition (e.g., has a pH of 7.5 or greater, such as 8.0 or greater). The composition includes a vehicle so that the composition can be applied, and at least one potential fragrance. The at least one potential fragrance has little or no odor, and is stable in the alkaline composition (e.g., in an alkaline solution including water). However, upon lowering the pH of the environment of the potential fragrance, the potential fragrance reacts (e.g., is hydrolyzed) to release an odorous portion of the potential fragrance, thereby providing a fragrance (e.g., a relatively strong, pleasant smelling aroma). 
     More specifically, the present invention provides a composition for contacting human skin, having a body activated fragrance that is odorless or of a low level of odor when applied to the skin (e.g., applied to the skin in an alkaline vehicle, having a pH greater than 7.5) and which is converted by natural skin pH changes (due to the buffer capacity of the skin) into a pleasant smelling substance, e.g., by hydrolysis of the compound to release the odorous portion of the molecule, and method of using such composition. 
     Various specific materials which are stable at alkaline pH (e.g., greater than pH=7.5), yet which undergo hydrolysis at a more acidic pH range (e.g., at most pH=7.5) to produce pleasant odors, can be incorporated in the composition of the present invention. Specifically, and illustratively (without limitation), acetals or ketals, e.g., of carbonyl compounds, which are stable with respect to hydrolysis at alkaline pH (e.g., greater than pH=8.0; preferably, greater than pH=7.5), yet which undergo hydrolysis at a more acidic pH range and which produce pleasant odors upon hydrolysis, are useful as the potential fragrances or body activated fragrances of the composition of the present invention. Hereinafter, by acetals or ketals, useful in the present invention, we mean acetals, or ketals, of fragrance materials which exhibit the desired pH-dependent hydrolysis behavior and resultant odor (e.g., pleasant aroma) after hydrolysis. The composition can be applied to the skin, using a suitable vehicle, and can achieve delayed release of fragrance (after application to the skin). 
     Another class of compounds useful as potential fragrances in the present invention are orthoesters. These orthoester compounds generally have the formula: ##STR1## where at least one of R 1 , R 2 , R 3  and R 4  is capable of forming a material having a fragrance upon hydrolysis of the orthoester. More specifically, (and illustratively, while not limiting), R 1  can be H, CH 3 , phenethyl, cinnamyl, phenylpropyl, benzyl, santalyl, etc.; and R 2 , R 3  and R 4  can be identical to each other or different, and can be CH 3 , phenethyl, cinnamyl, phenylpropyl, benzyl, santalyl, etc. (R 2 , R 3  and R 4  cannot be H); however, if R 1  is CH 3  or H, then R 2 , R 3  and R 4  cannot all be CH 3  (that is, at least one of R 1  -R 4  must be phenethyl, cinnamyl, phenylpropyl, etc., i.e., a radical that forms a material with a fragrance upon hydrolysis). Thus, at least one of R 1  -R 4  must be a radical that forms a material with a fragrance upon hydrolysis. 
     The compounds as described in the foregoing can be utilized in the various personal care and skin care products as discussed in the foregoing, in the form of a solution, lotion, cream or other emulsion, gelled stick, aerosol, spray or liquid roll-on; and, in particular, can be utilized to provide delayed release of fragrance in a transparent (clear) deodorant or antiperspirant stick product. 
     The composition of the present invention is an alkaline composition, or, if non-aqueous, is capable of providing an alkaline composition in contact with water. Hereinafter, when we refer to a composition capable of providing an alkaline composition when in contact with water, we mean both (1) an alkaline composition (e.g., an alkaline composition containing water) and (2) a composition which will be alkaline in contact with water (e.g., an anhydrous composition but which will be alkaline in contact with water). The compositions of the present invention are not acidic. In acidic compositions, the potential fragrance would hydrolyze, releasing fragrance prior to application. 
     As is clear from the prior paragraph, the present invention does not require a water-based (or even water-containing) composition. For example, various powder compositions and gelled stick compositions fall within the present invention. Powders (e.g., baby powder, talcum powder) can be, for example, non-aqueous. Certain gelled sticks (e.g., stearyl alcohol-cyclomethicone (Dow Corning Corp.)) are also non-aqueous. Moreover, compositions according to the present invention (e.g., clear or transparent compositions, such as clear or transparent stick compositions) can contain relatively small amounts of water, e.g., about 5% by weight. Such clear or transparent compositions containing 5% by weight water are illustrative, and such compositions can contain more or less than 5% by weight of water. 
     Since the composition according to the present invention is to be alkaline (or, if, e.g., non-aqueous, alkaline in contact with water or water-containing substances), there is a need to ensure the presence of water-soluble, alkaline pH producing ingredients in any composition containing any amount of water (or which will come into contact with any amount of water prior to application). In this regard, a composition which contains as little as 0.5% by weight water can cause some degree of hydrolysis, especially if other polar solvents such as ethanol or propylene glycol are present. Such water-soluble, alkaline pH producing ingredients, commonly used in the art, include sodium bicarbonate, calcium or magnesium hydroxide, calcium or magnesium oxide, alkaline earth and alkali metal silicates, alkanolamines, tris (hydroxymethyl) aminomethane (TRIS buffer), sodium hydroxide, etc. Such water-soluble, alkaline pH producing ingredients can be used for either aqueous (water-containing) or non-aqueous compositions; however, for non-aqueous compositions, powders such as sodium bicarbonate, magnesium oxide, etc., are preferred. 
     The presently described potential fragrances can be used in non-acidic antiperspirant compositions, with antiperspirants that are alkaline in nature (e.g., sodium aluminum lactate). However, presently used antiperspirant compositions include antiperspirants that are acidic in nature (e.g., aluminum chlorohydrate); the potential fragrance, if used in such presently used antiperspirant compositions containing acidic antiperspirants, will not attain the objective of delayed release of fragrance upon contact with, e.g., sweat. 
     In summary, according to one aspect of the present invention a &#34;potential fragrance&#34;, which exhibits little or no odor when present in an alkaline composition, and is applied to human skin in an alkaline composition (or in a composition capable of producing an alkaline pH when in contact with water), hydrolyzes on human skin as the skin pH is naturally lowered following alkaline insult due to application of the alkaline material to the skin. The resulting hydrolysis product, which is odorous, imparts a pleasant smell to the skin. Again, the basis for the hydrolyzing of the potential fragrance is the strong buffer capacity of the human skin to maintain a skin surface pH in the acidic range of 5.5-7.0, depending upon skin and population, the skin buffer capacity neutralizing the alkalinity caused by the application of alkaline material to the skin and restoring normal pH (to thereby cause the hydrolysis). 
     Typically, several different potential fragrances (for example, several different carbonyl acetals or ketals) are compounded together into the alkaline formulation, to be applied to the skin, to ensure formulation of desirable &#34;fragrances&#34; or odors following hydrolysis on the skin. 
     In a further aspect of the present invention, sodium stearate-based deodorant sticks containing water, propylene glycol, monohydric alcohols, optionally other fragrances and colors, and including potential fragrances as discussed previously (including, specifically, orthoesters, and/or acetals or ketals of carbonyl compounds as discussed above) can be provided to achieve delayed release of fragrance after application to the skin, while still maintaining a transparent or clear deodorant product. 
     Accordingly, by the present invention a product can be provided having delayed release of fragrance (e.g., a fragrancing product for contact with human skin, such as a personal care or skin care product, can be provided having delayed release of fragrance, delayed until after contact with the human skin; that is, a body activated fragrance), without the need of standard techniques for delayed release including, e.g., micro-encapsulation; moreover, the present invention enables formation of a transparent (clear) deodorant or antiperspirant stick product having delayed release of fragrance. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 demonstrate the pH-dependent hydrolysis of a specific orthoester. 
     FIGS. 3 and 4 demonstrate the pH-dependent hydrolysis of another specific orthoester. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention will be described in connection with specific and preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alterations, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     Throughout the present description, where it is disclosed that the composition and method include or comprise specific materials or steps, it is also within the contemplation of the present invention that the composition or method consists essentially of, or consists of, the recited materials or steps. 
     The present invention contemplates a composition for delayed release of fragrance; and in particular, a composition for application to the skin of a human (for example, a personal care product or skin care product), having potential fragrance components that are odorless or of a low level of odor prior to application, but which change into a pleasant smelling substance after contact with the skin (in particular, having a body activated release of fragrance). The composition is alkaline when in contact with or containing water, and includes a vehicle and at least one potential fragrance component (in addition to any other fragrance components and/or other components such as coloring), the potential fragrance component being odorless or of a low level of odor in alkaline conditions (an environment of pH of, for example, 9.5-10), yet which hydrolyzes at lower pH to produce the pleasant smelling substance. The decrease in pH is achieved upon contact with the skin, which due to the skin&#39;s buffer capacity will neutralize the alkaline composition to provide an environment for the potential fragrance component that will cause hydrolysis of the potential fragrance to produce the pleasant smelling substance. 
     As indicated previously, various acetals or ketals, e.g., acetals or ketals of carbonyl compounds, which are stable with respect to hydrolysis at alkaline pH (e.g., pH of greater than 8.0, preferably, pH greater than 7.5) but which undergo hydrolysis at a more acidic pH, and which produce pleasant odors upon hydrolysis, are useful as the potential fragrances or body activated fragrances incorporated in the compositions of the present invention. Specific compounds useful as potential fragrances according to the present invention are listed in the following as Formulae I-IV. ##STR2## 
     Other such acetals or ketals that are hydrolyzable under more acidic conditions to form an odoriferous compound, but which are stable and have little or no odor under more alkaline conditions, include (illustratively) citral butanetriol acetal, α-amyl cinnamaldehyde dimethyl acetal, and α-amyl cinnamaldehyde butanetriol acetal. 
     Generally, the acetals and ketals that can be used according to the present invention include (but are not limited to) heliotropine polyol acetal, ionone dialkyl ketal, methyl naphthyl ketone dialkyl ketal, citral polyol acetal, α-amyl cinnamaldehyde dialkyl acetal, α-amyl cinnamaldehyde polyol acetal, vanillin dialkyl acetal, vanillin alkylene acetal, anisic aldehyde dialkyl acetal, anisic aldehyde polyol acetal, citral dialkyl acetal, and vanillin polyol acetal. Specific compounds within the scope of these acetals and ketals include ionone dimethyl ketal, ionone diethyl ketal, methyl naphthyl ketone dimethyl ketal, methyl naphthyl ketone diethyl ketal, citral ethylene glycol acetal, citral butanediol acetal, citral butanetriol acetal, citral propylene glycol acetal, α-amyl cinnamaldehyde dimethyl acetal, α-amyl cinnamaldehyde diethyl acetal, α-amyl cinnamaldehyde propylene glycol acetal, α-amyl cinnamaldehyde butanetriol acetal, α-amyl cinnamaldehyde ethylene glycol acetal, vanillin dimethyl acetal, vanillin diethyl acetal, vanillin ethylene acetal, vanillin propylene acetal anisic aldehyde dimethyl acetal, anisic aldehyde diethyl acetal, anisic aldehyde propylene glycol acetal, anisic aldehyde butanetriol acetal, anisic aldehyde ethylene glycol acetal, citral dimethyl acetal, citral diethyl acetal, and vanillin propylene glycol acetal. 
     Illustratively, the acetals and ketals can be synthesized by a technique which is a modification of the methods described in Organic Syntheses Collective Volume 3, pages 731-732. An example of this technique is shown in the following. Of course, such technique is illustrative and not limiting. 
     A mixture of beta-methyl naphthyl ketone (200 g), trimethyl orthoformate (430 g) and toluene (250 ml) were stirred under nitrogen atmosphere for 10 min. To this mixture, 1.8 ml of (47%) BF 3  OEt 2  was added and stirred for 48 hours at room temperature, washed with aqueous NaHCO 3  and saturated NaCl solution. The mixture was then dried over Na 2  SO 4 , concentrated and distilled under reduced pressure to give 192 g of beta-methylnaphthylketone dimethyl ketal. 
     b.p. 113°-116° C./1.5mmHg 
     NMR(CDCl 3 ): 1.62(3H,s), 3.25(6H,s), 7.4-8.1(7H,m) 
     IR(neat): 3055, 1680, 1280 
     MS m/z: 184(M +  -MeOH) 
     Also, shown in the following are illustrations of the hydrolysis reactions which take place under acidic conditions, to release the pleasant smelling substances from the potential fragrances. The specific formulae for the following are the four above-listed compounds I-IV. ##STR3## 
     The foregoing compounds and reactions are merely illustrative of various acetal and ketal compounds, and fragrance materials formed therefrom, which can be utilized according to the present invention. In general, the acetals and/or ketals can be selected based upon the fragrances desired, and upon the following considerations to obtain a long-lasting fragrance. Thus, acyclic acetals hydrolyze faster than cyclic acetals. Acetals hydrolyze more quickly than ketals. Acetals formed from short-chain alcohols hydrolyze faster than acetals formed from longer-chain alcohols. Dimethyl acetals (DMA), diethyl acetals (DEA) and propylene glycol acetals (PGA) generally hydrolyze quickly at a pH of 6 (within the range of normal pH values of the skin); larger acetals will also hydrolyze, but more slowly and at lower pH. Allylic conjugation with the hydrolysis site results in faster hydrolysis than non-conjugation. Electron-donating substituents on an aromatic ring with the hydrolysis site increase the rate of hydrolysis. And electron-donating groups at the alpha position of an olefin conjugated to the hydrolysis site decrease the rate of hydrolysis. 
     Not only can such acetals or ketals (e.g., acetals or ketals of carbonyl compounds, such as acetals or ketals of conjugated carbonyl compounds) be utilized, but also other compounds, including (but not limited to) esters, amides and hydrolyzable derivatives of carbonyl compounds, capable of producing pleasant odors, can be utilized according to the present invention. 
     As mentioned previously, another class of compounds useful as potential fragrances in the present invention are orthoesters, generally represented by the formula ##STR4## where at least one of R 1  -R 4  forms a fragrance material upon hydrolysis of the orthoester. More specific definitions of R 1  -R 4  have previously been given. 
     In the following is set forth illustrative types of orthoester compounds for use in the present invention. These orthoester compounds are illustrative and not limiting, and show (particularly with the aforementioned acetals and ketals, esters, amides, etc.) the wide range of potential fragrances which can be used as part of the present invention. In the illustrative types of orthoesters in the following, R 1  -R 4  refer to the R 1  -R 4  of the formula for orthoesters in the immediately preceding paragraph. ##STR5## where R 4  can be phenethyl, cinnamyl, phenylpropyl, benzyl, geranyl, citronellyl, C-3-hexenyl and santalyl; ##STR6## where R 1  can be phenyl, cinnamyl or benzyl; ##STR7## where R 2  -R 4  can be the same or different, and can be phenethyl, cinnamyl, phenylpropyl, benzyl, geranyl, citronellyl, C-3-hexenyl, and santalyl (the same moieties for R as in the formulae Va and Vb). 
     The orthoesters can be synthesized by techniques known to those skilled in the art. Illustratively, an example of such techniques is shown in the following. Of course, such technique is illustrative and not limiting. 
     Synthesis of triethyl orthophenylacetate 
     To a mixture of dry ethanol (20 g) and dry chloroform (15 ml), 50 g of benzylnitrile was added and stirred at 10°-15° C. To this mixture, dry hydrochloride (15.6 g) was introduced. After 48 hours at room temperature, dry ethanol (100 ml) was added, and then left at room temperature for 2 days. The mixture was poured into a 5% NaOH solution. Then extraction was performed with chloroform and concentrated to give an oil (43 g). Triethyl orthophenylacetate was refined by distillation. (b.p 69°-71° C./1.5 mmHg, NMR(δ) 1.1-1.3(9H,m), 3.1(2H,s), 3.5-3.6(6H,m), 7.2-7.4(5H,m)). 
     Also, shown in the following (E) and (F) are illustrations of the hydrolysis reactions which take place under acidic conditions, to release the pleasant smelling substances from the orthoester potential fragrances. The specific formulae for the following are the above-described compounds Va, Vb, VI and VII. Also described in the following are the fragrance materials formed, for a given R 4 . ##STR8## Acid-hydrolyzed products of (E) and (F) are shown in the following Table A. 
     
                       TABLE A                                                     
______________________________________                                    
Identity of R.sub.4 in                                                    
starting material                                                         
           Hydrolysis Products                                            
______________________________________                                    
Phenethyl  Rose P, Rose P acetate (formate)                               
Cinnamyl   Cinnamic alcohol, Cinnamyl acetate (formate)                   
Phenylpropyl                                                              
           Phenylpropyl alcohol                                           
           Phenylpropyl acetate (formate)                                 
Benzyl     Benzyl alcohol, Benzyl acetate (formate)                       
Geranyl    Geraniol, Geranyl acetate (formate)                            
Citronellyl                                                               
           Citronellol, Citronellyl acetate (formate)                     
c-3-Hexenyl                                                               
           c-3-Hexenol, c-3-Hexenyl acetate (formate)                     
Santalyl   Santalol, Santalyl acetate (formate)                           
 ##STR9##                                                                 
Acid-hydrolyzed products of (G) are shown in the following                
Table B.                                                                  
______________________________________                                    
 
    
     
                       TABLE B                                                     
______________________________________                                    
Identity of R.sub.1 in                                                    
starting material Hydrolysis Products                                     
______________________________________                                    
Phenyl            Methyl benzoate                                         
Cinnamyl          Methyl cinnamate                                        
Benzyl            Methyl phenylacetate                                    
 ##STR10##                                                                
R is the same as R.sub.2, R.sub.3 and R.sub.4 of Formula VII. Each R can  
be                                                                        
the same or different, and can be of any of the starting                  
materials listed for &#34;R.sub.4 &#34; in Table A.                               
______________________________________                                    
 
    
     FIGS. 1 and 2 demonstrate the pH-dependent hydrolysis of a specific orthoester, where (in the general formula for orthoesters) R 1  =H, R 2  =phenethyl, and R 3  =R 4  =CH 3 . FIG. 2 shows that at pH=9.5, the concentration of the specific orthoester, representing 90% of the contents of a reaction mixture, is unchanged over a 24-hour period while the hydrolysis product, phenethyl alcohol, is unchanged over a 24-hour period at close to 0% of the reaction mixture. On the other hand, FIG. 1 shows that at pH=6.5, the orthoester hydrolyzes rapidly and in about 9 hours has essentially disappeared from the reaction mixture. The fragrance material phenethyl alcohol has increased in concentration to completely replace the starting material. Thus, FIGS. 1 and 2 demonstrate use of a specific orthoester as a potential fragrance, whereby at lower pH a material providing a fragrance is released from the orthoester. 
     FIGS. 3 and 4 demonstrate the pH-dependent hydrolysis of dimethyl cis-3-hexenyl orthoformate, where (in the general formula for orthoesters) R 1  =H, R 2  =cis-3-hexenyl, and R 3  =R 4  =CH 3 . FIG. 4 shows that, at pH=8.6, and from a reaction mixture wherein the orthoester represents 70-80% of the mixture, only a small percentage of the orthoester hydrolyzes over a 24-hour period, while the hydrolysis product, cis-3-hexenol, represents 0.-35% of the mixture after 24 hours. At a pH of 9 or higher, the concentration of hydrolysis product is unchanged over a 24-hour period, at close to 0% of the reaction mixture. On the other hand, FIG. 3 shows that at pH=6.5, the orthoester hydrolyzes rapidly and in about 7 hours has essentially disappeared from the reaction mixture. Thus, FIGS. 3 and 4 demonstrate use of a different orthoester, than the orthoester used in connection with FIGS. 1 and 2, as a potential fragrance, whereby at lower pH a material providing a fragrance is released from the orthoester. 
     Various compositions, for contact with the skin, fall within the scope of the present invention, including various skin care and personal care products. Based upon the specific vehicle utilized, the compositions are useful as liquid roll-on compositions, powders, spray compositions, aerosol compositions, stick compositions and cream compositions, applied to the human skin. For example, the compositions according to the present invention, utilizing a vehicle known in the art, and possibly other components, including, e.g., water, to form an alkaline composition, can be used for underarm deodorants, hand lotions, baby powder, baby lotions, ointments, foot products, facial cleansers, body wipes, facial make-up, colognes, after-shave lotions and shaving creams. 
     Apart from the incorporation of the potential fragrance as discussed in the foregoing, and the necessity of an alkaline environment (e.g., an alkaline vehicle) or an environment which becomes alkaline when in contact with water, the compositions according to the present invention can include conventional components which are used in conventional compositions, e.g., for liquid roll-ons, sprays, aerosols, creams and stick products. Thus, conventional components of various skin care and personal care products (e.g., stick deodorants, baby powders, hand lotions, baby lotions, etc.) can also be incorporated within the compositions according to the present invention, as long as such components do not so affect composition pH such that hydrolysis of the potential fragrance occurs, and as long as such components are inert to the potential fragrance (or as long as such components do not prevent the potential fragrance from releasing the pleasant smelling substance by, e.g., hydrolysis after application of the composition to the skin). 
     Of course, the compositions according to the present invention can include conventional fragrances, as long as such fragrances are inert to the potential fragrances of the present invention and do not so affect the pH of the composition such that hydrolysis of the potential fragrances occur. 
     The compositions according to the present invention can be manufactured by techniques known in the art; and are applied in the same manner as corresponding conventional compositions (e.g., conventional liquid roll-ons, sprays, aerosols, stick products and cream products). 
     The total concentration of potential fragrances in the compositions according to the present invention illustratively may range from 0.05%-3% by weight, although such concentration is not limited. Also illustratively (and not limiting), the potential fragrance may represent 10%-100% of the total amount of fragrance ingredient in the composition. 
     As indicated previously, a plurality of potential fragrances (for example, several carbonyl acetals or ketals) preferably are compounded together in an alkaline formulation to ensure a formulation having a desirable set of &#34;fragrances&#34; or odors following hydrolysis, after application to the skin. 
     As indicated previously, the present invention, incorporating potential fragrances into compositions for contact with human skin, is particularly appropriate in connection with stick deodorant or antiperspirant products that are clear or transparent. Suitable formulations include sodium stearate-based deodorant sticks containing water, propylene glycol, monohydric alcohols, other fragrances, and color. However, the present invention is not limited to use of the potential fragrances in clear or transparent stick compositions, and also includes various compositions wherein solutions, lotions, creams and other emulsions are used as vehicles for the composition (personal care or skin care product) applied to the skin. 
     EXAMPLE 1 
     This example shows hydrolysis of various acetals or ketals of carbonyl compounds in acidic conditions, or in sweat with epidermal bacteria LT (arthrobacter species) and H6 (various of staphylococcus epidermidis), which acetals or ketals are stable under basic (alkaline) conditions. Hydrolysis of the various compounds was tested in sweat or water, as indicated. 
     The following four types of materials were tested for hydrolysis of the acetal or ketal: 
     (1) acetal in sweat or water; 
     (2) glucoside and ester in water; 
     (3) acetal and ketal by strain LT (or H6) in sweat (LT is Arthrobacter s.p., and H6 is staphylococcus epidermis); and 
     (4) glucoside and ester with strain LT in sweat. 
     The procedure in connection with (1) and (2) above was as follows: 
     The pH of a mixture of acetal or ketal (300 μl), Nonipol 130 (Sanyo Kasei Co., Ltd.) (300 μl), Tween 80 (60 μl), and sweat (120 ml) or water (120 ml of distilled water) was regulated, and then the mixture was sterilized through a 0.45 μm micro filter. The sterilized mixture was shaken for 24 hours at 37° C. The degree of hydrolysis was then checked by gas chromatography using a dibenzyl compound as an internal standard after 3, 6, 9 and 24 hours. 
     The procedure in connection with (3) and (4) of the foregoing was as follows: 
     A mixture of acetal (or ketal) in an amount of 300 μl, Nonipol 130 (300 μl), Tween 80 (60 μl) and sweat (120 ml) was sterilized through a 0.45 μm micro filter. To the sterilized mixture, strain LT (or H6) was added, and the resultant mixture was shaken for 24 hours at 37° C. The resulting material was checked by gas chromatography using a dibenzyl as an internal standard after 3, 6, 9 and 24 hours. 
     The results of the foregoing experiment are shown in the following Table 1: 
     
                       TABLE 1                                                     
______________________________________                                    
                             REACTIVITY                                   
COM-     ME-                 (% reacted)                                  
POUND    DIA     PH      strain                                           
                               3 hr 6 hr 9 hr 24 hr                       
______________________________________                                    
Heliotropine                                                              
         sweat   7.7-8.2 --    0    0    0    1.7                         
ethylene water   7.2-7.9 --    0.4  3.6  5.6  11.0                        
glycol acetal                                                             
         sweat   7.6-8.0 LT    2.2  4.0  5.9  12.4                        
         sweat   7.5-7.7 H6    1.5  3.0  5.7  16.2                        
         sweat   6.2-6.4 --    18.1 32.4 40.7 64.7                        
         water   5.7-5.8 --    63.8 65.7 66.7 68.5                        
Ionone di-                                                                
         sweat   7.6-7.8 --    2.4  19.0 32.8 25.9                        
methyl ketal                                                              
         water   6.7-7.1 --    18.8 30.6 33.5 28.3                        
         sweat   7.4-7.6 LT    0.8  0.1  7.7  30.7                        
         sweat   7.3-7.7 H6    18.5 18.1 16.0 28.8                        
         sweat   6.4-6.6 --    36.4 45.8 44.8 29.1                        
         water   6.9-7.0 --    13.0 14.8 28.8 13.8                        
Methyl   sweat   7.7-8.1 --    0.0  0.0  2.5  12.4                        
naphtyl  water   7.3-8.1 --    0.0  1.2  6.4  20.0                        
ketone di-                                                                
         sweat   7.6-7.8 LT    0.0  0.3  3.6  8.8                         
methyl ketal                                                              
         sweat   7.5-7.7 H6    1.1  5.8  7.6  20.5                        
         sweat   6.3-6.4 --    26.1 40.2 50.1 83.3                        
         water   6.2-6.4 --    54.4 75.8 87.9 93.7                        
Citral butane-                                                            
         sweat   6.9-7.3 --    1.5  6.9  10.3 14.6                        
triol acetal                                                              
         water   8.2-9.3 --    0.0  0.1  0.3  0.3                         
         sweat   7.0-7.2 LT    4.3  7.5  12.1 20.8                        
         sweat   7.5-7.9 H6    4.5  5.8  6.8  9.4                         
         water   6.6-7.0 --    40.8 66.1 76.8 46.8                        
α-Amyl                                                              
         sweat   7.7-8.2 --    1.1  1.3  4.4  4.4                         
cinnamalde-                                                               
         water   7.2-8.0 --    0.0  0.0  1.0  3.3                         
hyde di- sweat   7.5-7.7 LT    0.0  0.0  0.6  0.1                         
methyl acetal                                                             
         sweat   7.2-7.5 H6    0.0  0.4  0.5  0.6                         
         sweat   6.3-6.4 --    10.5 11.5 21.9 24.6                        
         water   3.5-6.2 --    5.9  12.9 22.1 36.6                        
α-Amyl                                                              
         sweat   7.8-8.2 --    3.2  3.4  3.9  0.6                         
cinnamalde-                                                               
         water   7.4-8.2 --    0.0  0.0  0.0  0.1                         
hyde butane-                                                              
         sweat   7.5-7.7 LT    0.8  0.1  0.1  0.3                         
triol acetal                                                              
         sweat   6.3-6.5 --    2.2  2.3  0.8  3.4                         
         water   6.2-6.5 --    0.0  0.0  0.4  2.5                         
Vanillin sweat   6.8-7.8 --    14.2 39.7 35.9 56.7                        
propylene-                                                                
         water   7.0-7.9 --    10.8 20.3 22.9 49.5                        
glycol acetal                                                             
         sweat   6.5-6.9 --    25.1 42.6 50.0 75.1                        
         water   6.2-6.3 --    20.9 39.2 48.2 69.8                        
Decanal  sweat   7.3-7.9 --    Not hydrolyzed                             
diethyl acetal                                                            
         water   7.0-7.5 --                                               
         sweat   6.5-6.9 --                                               
         water   6.2-6.8 --                                               
Decanal  sweat   7.6-7.8 --    Not hydrolyzed                             
propylene-                                                                
         water   7.5-8.3 --                                               
glycol acetal                                                             
         sweat   7.5-7.7 LT                                               
C-3-Hexenyl                                                               
         sweat   7.5-7.7 LT    Not hydrolyzed                             
glucoside                                                                 
         water   6.5-6.8                                                  
Phenethyl                                                                 
         sweat   7.5-7.7 LT    Not hydrolyzed                             
acetate  water   6.0-7.0 --                                               
Geranyl  sweat   7.5-7.7 LT    Not hydrolyzed                             
acetate  water   6.0-7.0 --                                               
______________________________________                                    
 
    
     As can be seen in the foregoing Table 1, conjugated carbonyl compounds were hydrolyzed in acidic water or in weak acidic sweat. More reactive aromatic compounds were. hydrolyzed even in basic (alkaline) conditions (under pH=8); but in more basic (alkaline) conditions (pH=8-9), acetal or ketal compounds were not hydrolyzed. 
     From the foregoing, it can be seen that acetals or ketals of various carbonyl compounds are hydrolyzed to original carbonyl compounds in acidic media (pH=6-7). Acetals or ketals of carbonyl aromatic compounds (vanillin, heliotropin and methyl naphthyl ketone) are hydrolyzed even in mildly basic solutions; also, ionone dimethyl ketal and vanillin propylene glycol acetal are hydrolyzed to ionone and vanillin both in acidic and basic conditions (pH=7-8); however, acetals or ketals of certain non-conjugated carbonyl compounds, and of esters and glucoside, are not hydrolyzed to the original compounds. In addition, the strains LT and H6 cannot accelerate hydrolysis of acetal, ketal, glucoside and ester in sweat or in water. 
     EXAMPLE 2 
     The pH of a mixture of Dimethyl phenyl orthoformate (0.3 g), Nonipol 130 (0.5 g) and N-Cetane (0.1 g) as internal standard was regulated by phosphate buffer solution (50 ml), and then the mixture was shaken for 24 hours at 37° C. The degree of hydrolysis was then checked by gas chromatography after 4, 9, and 24 hours. The conditions for the gas chromatography include the following: 
     column: OV-10.25 mm×25 m 
     temperature: 100°-220° (4°/min.) 
     The results are demonstrated as FIG. 3 and FIG. 4. 
     EXAMPLE 3 
     This example shows the results of hydrolyzing various acetals and ketals at a pH of 6. The hydrolysis procedure used is described in the following. A pH 6 phosphate buffer solution (Fisher) was prepared containing two nonionic surfactants (Igepal CO-720, 0.25% (Aldrich) and Tween 80, 0.05% (Aldrich)) to ensure solubility of the potential fragrances. To 5 ml of the pH 6 buffer was added a solution of 5 mg of the potential fragrance in 0.2 ml EtOAc and 20 μl of internal standard solution (0.6M methyl stearate in EtOAc). The solution was stirred and incubated at 37° C., and 0.5 ml aliquots were removed periodically. Each aliquot was extracted with 0.5 ml EtOAc, and 1 μl of the EtOAc layer was analyzed by gas chromatography (Hewlett Packard 5890 GC equipped with a FID and 12 m DB-5 capillary column). Quantitation of the hydrolysis was performed by monitoring the disappearance of the potential fragrance, relative to the internal standard. 
     The potential fragrances tested, are shown in Table 2. These potential fragrances were purchased or synthesized as described in the following. 
     4-Butylbenzaldehyde DEA, benzaldehyde DMA, and hydroxycitronellal DMA were obtained from Aldrich. Vanillin PGA was obtained from Pfaltz &amp; Bauer, Inc. Amyl cinnamaldehyde DEA and DMA, anisaldehyde DEA and PGA, benzaldehyde PGA, citral DMA and PGA, decanal DEA, dodecanal DMA, heliotropin DEA, heridon, hyacinth DMA and GA (glyceryl acetal), hydratropic aldehyde DMA, isobutyl aldehyde DEA, laurinal DEA, leaf acetal, nonanal DMA, talia, and troenan were provided by Takasago International Corporation (Tokyo, Japan). All other acetals and ketals were synthesized using the general procedures below. 
     Diethyl acetals. 
     Suzaral DEA. 
     To a THF (500 ml) solution of suzaral (115 mM) was added triethyl orthoformate (172 mM) and a catalytic amount of p-toluenesulfonic acid monohydrate (1.15 mM). The reaction flask was equipped with a Dean-Stark trap packed with 3 Å molecular sieves and refluxed until the reaction was complete. Solvent and residual triethyl orthoformate were removed by rotary evaporation. Vacuum distillation (97° C., 400 mtorr) afforded a colorless oil (66% yield). Mass: [M]+ m/e 278.  1  H-NMR (500 MHz, CDCl 3 ) δ0.87 (m,9H), 1.24 (m,6H), 1.84 (m,1H), 2.05 (m, 1H), 2.28 (d,2H), 2.44 (d,2H), 3.50 (t,2H), 3.69 (t,2H), 4.20 (d,2H), 7.06 (m,4H). 
     Dupical DEA: 
     Colorless oil (87% yield). MS: [M]+ 278.  1  H-NMR: δ0.93 (m,2H), 1.04 (d,1H), 1.20 (2t,6H), (m, 1H), 1.65 (m,4H), 1.72 (t,1H), 1.85 (m,4H), 1.95 (m, 1H), 2.05 (m,3H), 2.33 (s, 1/2H), 2.65 (s, 1/2H), 3.47 (m,2H), 3.65 (m,2H), 4.47 (2t,1H) 4.95 (t, 1/2H), 5.17 (t, 1/2H). 
     Vanillin DEA: 
     Colorless oil (10% yield). MS: [M]+ 226.  1  H-NMR: δ1.25 (t,6H), 3.55 (m,2H), 3.65 (m,2H), 3.92 (s,3H), 5.4 (s,1H), 5.4 (s,1H), 6.88 (d,1H), 6.95 (d,2H), 7.05 (s,1H). 
     Diethyl ketals. 
     Methyl naphthyl ketone DEK (diethyl ketal). To an ethanol (64 ml) solution of methyl naphthyl ketone (0.27M) was added triethyl orthoformate (0.69M). An ethanol solution of hydrochloric acid (2.4M, 1.2 ml) was added and the reaction was stirred at room temperature for 2 days. Sodium ethoxide was added to quench the acid, followed by concentration under vacuum. The acetal was filtered through carbon and celite, washed with petroleum ether, and dried under high vacuum to afford a colorless oil (90% yield). MS:[M]+ 244.  1  H-NMR: δ1.24 (t,6H), 1.62 (s,3H), 3.47 (m,4H), 7.41 (m,2H), 7.6 (d,1H), 7.8 (m,3H), 8.05 (s,1H). 
     Acetyl tetralin DEK: 
     Colorless oil (90% yield). MS: [M]+ 248.  1  H-NMR: δ1.22 (t,6H), 1.52 (s,3H), 1.78 (m,4H), 2.75 (m, 4H), 3.44 (m, 4H), 7.01 (d, 1H), 7.2 (m, 2H). 
     Alpha ionone DEK: 
     Colorless oil (77% yield). MS: [M]+ 266.  1  H-NMR: δ0.8 (s,3H), 0.9 (s,3H), 1.15 (t,6H), 1.20-1.40 (m,2H), 1.38 (s,3H), 1.6 (s,3H), 2.0 (m,2H), 2.05 (d,1H), 3.45 (m,4H), 5.4 (m,2H), 5.65 (dd, 1H). 
     Cyclic Acetals. 
     Heliotropin PGA. 
     To a THF (300 ml) solution of heliotropin (169 mmoles) was added propylene glycol (211.3 mM) and p-toluene sulfonic acid monohydrate (1.69 mM). The reaction flask was equipped with a Dean-Stark trap packed with 3 Å molecular sieves and refluxed until complete. After concentration under reduced pressure the crude acetal was vacuum distilled (105° C., 450 millitorr), affording a colorless oil (75% yield). MS: [M]+ 208.  1  H-NMR: δ1.34 (d, 3/2H), 1.39 (d,3/2H), 3.54 (t,1/2H), 3.60 (t, 1/2H), 4.10 (t,1/2H), 4.26 (t,1/2H), 4.34 (dt,1H), 5.72 (s,1/2H), 5.86 (s,1/2H), 5.96 (s,2H), 6.78 (d,1H), 6.96 (m,2H). 
     Decanal PGA: 
     Colorless oil (70% yield). MS:[M]+ 214.  1  H-NMR: δ0.9 (t,3H), 1.3 (m,14H), 1.65 (m,2H), 3.4 (m, 1H), 3.9 (t,1/2H), 4.18 (m,3/2H), 4.9 (t,1/2H), 5.05 (t,1/2H). 
     Dodecanal PGA: 
     Colorless oil (68% yield). MS: [M]+ 242.  1  H-NMR: δ0.9 (t,3H), 1.3 (m,18H), 1.65 (m,2H), 3.4 (m, 1H), 3.9 (t,1/2H), 4.18 (m,3/2H), 4.9 (t,1/2H), 5.05 (t,1/2H). 
     Dupical PGA: 
     Colorless oil (70% yield). MS:[M]+ 262.  1  H-NMR: δ0.93 (m, 2H), 1.05 (d, 1H), 1.19 (m, 1H), 1.25 (d,3/2H), 1.30 (d,3/2H), 1.41 (m, 1H), 1.68 (m, 5H), 1.85 (m, 3H), 1.95-2.10 (m, 4H), 2.34 (s,1/2H), 2.68 (s,1/2H), 3.41 (m, 1H), 3.93 (m, 1/2H), 4.12-4.22 (m,3/2H), 4.98 (m, 1H), 4.98 (m, 1H), 5.20 (t,1/2H). 
     Heliotropin EGA: 
     Colorless oil (53% yield). MS: [M]+ 194.  1  H-NMR: δ4.00 (m, 2H), 4.09 (m, 2H), 5.71 (s, 1H), 5.96 (s,2H), 6.79 (m, 1H), 6.96 (m,2H). 
     Nonanal PGA: 
     Colorless oil (85% yield). MS: [M]+ 200.  1  H-NMR: δ0.87 (t,3H), 1.3 (m,12H), 1.64 (m,2H), 3.39 (m,1H), 3.93 (t,1/2H), 4.15 (m,3/2H), 4.89 (t,1/2H), 5.0 (t,1/2H). 
     Suzaral PGA: 
     Colorless oil (85% yield). MS: [M]+ 262.  1  H-NMR: δ0.88 (m,9H), 1.26 (d,3/2H), 1.30 (d,3/2H), 1.83 (m, 1H), 2.0 (m, 1H), 2.35 (m, 1H), 2.43 (d,2H), 2.85 (m, 1H), 3.40 (m, 1H), 3.96 (m,1/2H), 4.18 (m,3/2H), 4.81 (d,1/2H), 4.89 (d,1/2H), 7.0 (m,4H). 
     The results of the hydrolysis are also shown in Table 2. 
     
                       TABLE 2                                                     
______________________________________                                    
Hydrolysis results                                                        
Potential Fragrance                                                       
                 CAS Number Hydrolysis, pH 6                              
______________________________________                                    
4-butylbenzaldehyde diethyl                                               
                 83803-80-9 none, 24 hr                                   
acetal                                                                    
anisaldehyde diethyl acetal                                               
                 2403-58-9  100%, 1 hr                                    
anisaldehyde propylene glycol                                             
                 6414-32-0  80%, 8 hr                                     
acetal                                                                    
benzaldehyde dimethyl acetal                                              
                 1125-88-8  90%, 7 hr                                     
benzaldehyde propylene glycol                                             
                 2568-25-4  none, 24 hr                                   
acetal                                                                    
vanillin diethyl acetal                                                   
                 85377-01-1 99%, 0.75 hr                                  
vanillin propylene glycol                                                 
                 68527-74-2 89%, 6 hr                                     
acetal                                                                    
heliotropin diethyl acetal                                                
                 40527-42-2 100%, 2 hr                                    
heliotropin ethylene glycol                                               
                 4405-18-9  64.7%, 24 hr                                  
acetal                                                                    
heliotropin propylene glycol                                              
                 61683-99-6 84.8%, 48 hr                                  
acetal                                                                    
alpha ionone diethyl ketal                                                
                 13743-48-1 95.1%, 24 hr                                  
beta ionone diethyl ketal                                                 
                 13743-47-0 53.7%, 48 hr                                  
beta methyl ionone diethyl                                                
                 not registered                                           
                            42.6%, 24 hr                                  
ketal                                                                     
dupical diethyl acetal                                                    
                 not registered                                           
                            none, 45 hr                                   
dupical propylene glycol                                                  
                 not registered                                           
                            none, 48 hr                                   
acetal                                                                    
suzaral diethyl acetal                                                    
                 not registered                                           
                            none, 45 hr                                   
suzaral propylene glycol                                                  
                 not registered                                           
                            none, 48 hr                                   
acetal                                                                    
amyl cinnamic aldehyde                                                    
                 60763-41-9 18%, 24 hr                                    
diethyl acetal                                                            
amyl cinnamic aldehyde                                                    
                 91-87-2    24.6%, 24 hr                                  
dimethyl acetal                                                           
decanal diethyl acetal                                                    
                 34764-02-8 none, 24 hr                                   
decanal propylene glycol                                                  
                 5421-12-5  none, 24 hr                                   
acetal                                                                    
dodecanal dimethyl acetal                                                 
                 14620-52-1 none, 24 hr                                   
dodecanal propylene glycol                                                
                 82925-11-9 none, 48 hr                                   
acetal                                                                    
nonanal dimethyl acetal                                                   
                 18824-63-0 16%, 42 hr                                    
nonanal propylene glycol                                                  
                 68391-39-9 none, 48 hr                                   
acetal                                                                    
methyl naphthyl ketone                                                    
                 not registered                                           
                            60.1%, 48 hr                                  
diethyl ketal                                                             
acetyl tetralin diethyl                                                   
                 not registered                                           
                            91%, 48 hr                                    
ketal                                                                     
citral dimethyl acetal                                                    
                 7549-37-3  90%, 2 hr                                     
citral propylene glycol                                                   
                 10444-50-5 66.4%, 24 hr                                  
acetal                                                                    
hyacinth dimethyl acetal                                                  
                 101-48-4   none, 45 hr                                   
hyacinth glyceryl acetal                                                  
                 29895-73-6 none, 45 hi                                   
hydratropic aldehyde dimethyl                                             
                 90-87-9    none, 45 hr                                   
acetal                                                                    
hydroxycitronellal dimethyl                                               
                 141-92-4   none, 24 hr                                   
acetal                                                                    
laurinal diethyl acetal                                                   
                 7779-94-4  27.8%, 45 hr                                  
heridon          181-28-2   51%, 24 hr                                    
intreleven aldehyde diethyl                                               
                 not registered                                           
                            none, 24 hr                                   
acetal                                                                    
isobutyl aldehyde diethyl                                                 
                 1741-41-9  87.1%, 45 hr                                  
acetal                                                                    
leaf acetal      28069-74-1 55.9%, 45 hr                                  
talia            67633-92-5 14%, 42 hr                                    
troenan          480-24-6   9%, 42 hr                                     
______________________________________                                    
 
    
     The following conclusions can be drawn from these results. Acetals hydrolyze more quickly than ketals, and acyclic acetals hydrolyze more quickly than cyclic acetals. Acetals made from short-chain alcohols hydrolyze faster than acetals made from large alcohols. Dimethyl, diethyl and propylene glycol acetals generally hydrolyze quickly at a pH of 6; larger acetals will also hydrolyze, but more slowly and at a lower pH. Allylic conjugation with the hydrolysis site results in faster hydrolysis than hydrolysis of compounds with unsubstituted aryl conjugation. Electron-donating substituents on an aromatic ring in conjugation with the hydrolysis site increase the rate of hydrolysis; and electron-withdrawing groups at the beta position of an olefin conjugated to the hydrolysis site decrease the rate of hydrolysis. 
     In the following are set forth examples of potential fragrances incorporated in various products, according to the present invention. In the following examples, conventional methods of emulsification, gelation, co-solvency and mixing are used. The methods of forming the compositions are well known in the art. In many cases, especially when heating is required during processing, it is desirable to add the fragrances (regular or potential) last, to reduce fragrance loss due to volatilization or decomposition. 
     
         ______________________________________                                    
Example A.                                                                
Water Based Gelled Deodorant Sticks                                       
             % W/W                                                        
             1    2      3      4    5    6                               
______________________________________                                    
Sodium Stearate                                                           
               7.0    6.5    7.0  --   1.0  6.5                           
DBMSA          --     --     --   1.5  1.5  --                            
Magnesium Oxide                                                           
               --     --     --   --   --   10.0                          
Water          25.8   23.1   25.0 23.5 26.0 13.1                          
Ethanol        --     --     --   --   --   10.0                          
Propylene glycol                                                          
               66.0   69.0   45.0 30.0 40.0 59.0                          
Dipropylene glycol                                                        
               --     --     19.5 31.2 21.2 --                            
Sorbitol       --     --     --   3.5  3.5  --                            
M-pyrol        --     --     --   5.0  4.0  --                            
Dimethicone copolyol                                                      
               --     --     --   4.0  --   --                            
Triclosan.sup.∘                                               
               0.2    0.2    --   0.3  0.3  0.2                           
PPG-3-Myristyl ether.sup.∘∘                       
               --     --     2.0  --   1.0  --                            
Potential Fragrance*                                                      
               0.5    1.2    1.0  1.0  1.0  1.2                           
Regular Fragrance**                                                       
               0.5    --     0.5  --   0.5  --                            
               100.0  100.0  100.0                                        
                                  100.0                                   
                                       100.0                              
                                            100.0                         
______________________________________                                    
 .sup.∘ Vendor: Ciba Geigy                                    
 .sup.∘∘ Vendor: Croda Synthetic Chemicals Ltd.   
 *May be one or more potential fragrance ingredients                      
 **Fragrance of prior art  not a potential fragrance                      
 
    
     The procedure is known to those skilled in the art. It is desirable to add the fragrances last. 
     
         ______________________________________                                    
Example B.                                                                
Non-aqueous Gelled Deodorant Sticks                                       
                 % W/W                                                    
                 1     2                                                  
______________________________________                                    
Stearyl Alcohol    21.0    16.0                                           
Castorwax MP-70    --      4.0                                            
PPG-15-stearyl ether                                                      
                   --      3.0                                            
Glyceryl Monostearate                                                     
                   0.5     0.5                                            
PEG-100            0.5     0.5                                            
Cyclomethicone     60.5    57.5                                           
Magnesium Oxide    15.0    --                                             
Sodium bicarbonate --      16.0                                           
Potential fragrance                                                       
                   2.5     1.5                                            
Regular fragrance  --      1.0                                            
                   100.0   100.0                                          
______________________________________                                    
 Procedure:                                                               
 Melt the stearyl alcohol and castorwax at 70-80° C. While stirring
 add the glyceryl monostearate, PEG100 and PPG15 stearyl ether. While     
 cooling, add the cyclomethicone and maintain at 55-60° C. Add the 
 magnesium oxide or sodium bicarbonate. While stirring add the fragrances 
 last and cool.                                                           
 
    
     
         ______________________________________                                    
Example C.                                                                
Water-based Roll-on Deodorants                                            
            % W/W                                                         
            1      2       3        4                                     
______________________________________                                    
Water         44       45      73     78.0                                
Cyclomethicone                                                            
              33       30      --     --                                  
Magnesium Oxide                                                           
              15       --      15     5.0                                 
Sodium bicarbonate                                                        
              --       15      --     --                                  
Sodium silicate                                                           
              --       --      --     5.0                                 
Dinethicone copolyol.sup.∘                                    
               5        6      --     --                                  
(10% active)                                                              
Polysorbate 20.sup.∘∘                             
               1        2      --     --                                  
PPG-15 Stearyl ether                                                      
              --       --      5.0    5.0                                 
Steareth-2.sup.∘∘∘                    
              --       --      1.5    1.5                                 
Steareth-78.sup.∘∘∘∘      
              --       --      3.5    3.5                                 
Potential Fragrance                                                       
              1.5      1.0     2.0    2.0                                 
Regular Fragrance                                                         
              0.5      1.0     --     --                                  
              100.0    100.0   100.0  100.0                               
______________________________________                                    
 .sup.∘ Vendor: Dow Corning Ltd.                              
 .sup.∘∘ Vendor: Emery Industries Inc.            
 .sup.∘∘∘ Vendor: Brooks &amp; Perkin Inc.
 .sup.∘∘∘∘ Vendor: Brooks 
 Perkin Inc.                                                              
 
    
     
         ______________________________________                                    
Example D.                                                                
Suspension Deodorant Roll-Ons                                             
                 % W/W                                                    
                 1     2                                                  
______________________________________                                    
Cyclomethicone     66.5    74.0                                           
Bentone            2.5     2.5                                            
SD-40 Alcohol      1.0     1.0                                            
Magnesium Oxide    18.0    --                                             
Sodium bicarbonate --      15.0                                           
Dimethicone        10.0    --                                             
Isopropyl myristate                                                       
                   --      5.0                                            
Potential fragrance                                                       
                   2.0     1.5                                            
Regular fragrance  --      1.5                                            
                   100.0   100.0                                          
______________________________________                                    
 
    
     
         ______________________________________                                    
Example E.                                                                
Powder Compositions                                                       
           % W/W                                                          
           1      2        3        4                                     
______________________________________                                    
Talc         89.0     73.0     81.0   56.0                                
Cornstarch   --       15.0     --     30.0                                
Magnesium Oxide                                                           
             5.0      --       --                                         
Sodium bicarbonate                                                        
             --       10.0     --     4.0                                 
Calcium silicate                                                          
             --       --       2.0    --                                  
Oatmeal      2.0      --       15.0   5.0                                 
Potential fragrance                                                       
             2.0      1.0      1.5    3.0                                 
Regular fragrance                                                         
             1.0      1.0      0.5    --                                  
Dimethicone  1.0      --       --     2.0                                 
             100.0    100.0    100.0  100.00                              
______________________________________                                    
 
    
     
         ______________________________________                                    
Example F.                                                                
Baby Lotions                                                              
       % W/W                                                              
       1         2           3                                            
______________________________________                                    
Oil Phase                                                                 
Glyceryl 1.5         1.0         0.7                                      
stearate                                                                  
Isopropyl                                                                 
         1.5         1.0         1.3                                      
palmitate                                                                 
Lauramine.sup.∘                                               
         0.5         0.5         0.5                                      
Mineral oil                                                               
         1.5         1.0         1.0                                      
Stearic Acid                                                              
         0.8         0.8         1.0                                      
Cetyl    0.7         0.8         0.7                                      
Alcohol                                                                   
Propyl   0.1         0.1         0.1                                      
paraben                                                                   
Potential                                                                 
         1.3         1.0         1.5                                      
fragrance                                                                 
Regular  0.3         0.5         --                                       
fragrance                                                                 
Water Phase                                                               
Propylene                                                                 
         2.0         2.0         2.0                                      
glycol                                                                    
Carbomer --          0.1         --                                       
934                                                                       
Trimethamine                                                              
         1.0         0.8         1.2                                      
Tetrasodium                                                               
         0.5         0.5         0.6                                      
EDTA                                                                      
Sodium   q.s. to pH = 8.2                                                 
                     --          q.s. pH = 8.5                            
hydroxide                                                                 
Triethanol-                                                               
         --          q.s. to pH = 8.0                                     
                                 0.5                                      
amine                                                                     
Water    q.s. to 100.0                                                    
                     q.s. to 100.0                                        
                                 q.s. to 100.0                            
______________________________________                                    
 .sup.∘ Vendor: Akzo NV NL                                    
  Procedure:                                                              
 Heat water to 70° C. Add other water phase ingredients, adding the
 triethanolamine and/or sodium hydroxide last. Separately melt the content
 of the oil phase together, then add the oil phase to the water phase with
 agitation. Cool to set point and fill.                                   
 
    
     
         ______________________________________                                    
Example G.                                                                
Skin or Body Creams                                                       
               % W/W                                                      
               1       2                                                  
______________________________________                                    
Oil Phase                                                                 
Glyceryl Stearate                                                         
                 5.0       5.5                                            
Isopropyl Myristate                                                       
                 3.0       3.5                                            
Stearic Acid     2.5       2.0                                            
Propyl paraben   0.1       0.1                                            
Potential fragrance                                                       
                 1.5       0.7                                            
Regular fragrance                                                         
                 --        0.7                                            
Water Phase                                                               
Glycerine        6.0       6.0                                            
Triethanalamine  1.0       1.0                                            
Methyl paraben   0.2       0.2                                            
Tetrasodium EDTA 0.5       --                                             
Magnesium Oxide  3.0       3.5                                            
Water            q.s. to 100.0                                            
                           q.s. to 100.0                                  
______________________________________                                    
 Procedure similar to Baby Lotions                                        
 
    
     
         ______________________________________                                    
Example H.                                                                
Ointments                                                                 
            % W/W                                                         
            1        2       3                                            
______________________________________                                    
Zinc Oxide    20.0       25.0    12.0                                     
Magnesium Oxide                                                           
              --         --       8.0                                     
Mineral Oil   15.0       --      12.0                                     
White Ointment                                                            
              63.0       --      61.5                                     
White Petrolatum                                                          
              --         50.0    --                                       
Starch        --         23.0     5.0                                     
Potential fragrance                                                       
               2.0        1.0     1.0                                     
Regular fragrance                                                         
              --          1.0     0.5                                     
              100.0      100.0   100.0                                    
______________________________________                                    
 
    
     
         ______________________________________                                    
Example I.                                                                
After-Shave Lotions and Colognes                                          
                 % W/W                                                    
                 1     2                                                  
______________________________________                                    
Propylene glycol   2.0     2.0                                            
Ethanol            75.0    80.0                                           
Water              16.5    9.3                                            
Sodium bicarbonate 2.0     2.0                                            
Sodium hydroxide   0.2     --                                             
Tetrasodium EDTA   0.5     0.5                                            
Benzophenone - 4.sup.∘                                        
                   0.3     0.2                                            
Potential fragrance                                                       
                   2.0     2.0                                            
Regular fragrance  1.5     4.0                                            
                   100.0   100.0                                          
______________________________________                                    
 .sup.∘ Vendor: BASF AG                                       
 
    
     
         ______________________________________                                    
Example J.                                                                
Aerosol Deodorant Compositions                                            
                   1     2                                                
______________________________________                                    
Benzethonium chloride                                                     
                     0.21    --                                           
Dipropylene glycol   1.00    --                                           
SDA-40 Alcohol (anhydrous)                                                
                     65.00   0.75                                         
Potential fragrance  1.50    1.50                                         
Regular fragrance    0.50    --                                           
Hydrocarbon A-46 propellant                                               
                     --      74.00                                        
Hydrocarbon A-70 propellant                                               
                     31.40   --                                           
Trimethamine         0.39    --                                           
Cyclomethicone       --      12.00                                        
Isopropyl myristate  --      4.00                                         
Magnesium oxide      --      7.00                                         
Bentone 38           --      0.75                                         
                     100.0   100.00                                       
______________________________________                                    
 
    
     
         ______________________________________                                    
Example K.                                                                
Shaving Creams                                                            
                % w/w                                                     
______________________________________                                    
Stearic Acid      8.5                                                     
Triethanolamine   3.0                                                     
Potassium hydroxide                                                       
                  1.0                                                     
Polysorbate 20    1.2                                                     
Glycerin          2.2                                                     
Lauramide DEA     0.8                                                     
Isopropyl myristate                                                       
                  0.5                                                     
Water             79.3                                                    
A-46 Propellant   3.5                                                     
                  100.0                                                   
______________________________________                                    
 
    
     Accordingly, by the present invention, a composition, e.g., for application to the skin, containing a potential fragrance (that is, body activated fragrance, which under alkaline conditions has little or no odor but which releases a fragrance compound by hydrolysis, under acidic conditions, e.g., on the skin), achieves a delayed release of fragrance. By incorporating such potential fragrance in a sodium stearate-based deodorant or antiperspirant stick product, a transparent or clear deodorant or antiperspirant stick product can be achieved. 
     While we have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible to numerous changes and modifications as are known to one having ordinary skill in the art, and we therefore do not wish to be limited to the details shown and described herein, but intend to cover all such modifications as are encompassed by the scope of the appended claims.