Use of norbornyl esters in augmenting or enhancing the aroma or taste of smoking tobacco compositions and smoking tobacco articles
This is a divisional application under 37 CFR 1.60 of pending prior application Ser. No. 369,288, filed on July 8, 1982, now U.S. Pat. No. 4,435,316. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to substituted norbornyl ester derivatives of the genus of compounds having the structure: ##STR2## wherein R 1 , R 2  and R 3  represents methyl or hydrogen with at least one of R 1 , R 2  and R 3  being hydrogen and uses thereof in order to alter, modify or enhance the aroma or taste of consumable materials. 
     There has been considerable work performed relating to substances which can be used to impart (modify, augment or enhance) fragrances and tastes to (or in) various consumable materials. The substances are used to diminish the use of natural materials some of which may be in short supply and to provide more uniform properties in the finished product. 
     Sweet, amber-like, powerful long-lasting green, herbaceous, floral, fruity, powerful anisic and bergamot-like aroma nuances are desirable in several types of perfume compositions, perfumed articles and colognes. 
     Sweet, licorice-like, anise oil-like, spicy, fresh dandelion leaf and raw spinach aroma and taste nuances with faint scallion-like nuances are desirable in augmenting or enhancing the aroma and/or taste of foodstuffs, chewing gums, medicinal products, chewing tobaccos and toothpastes. 
     Turkish-like tobacco nuances are particularly desirable in augmenting or enhancing the aroma or taste of smoking tobacco and smoking tobacco article components both prior to smoking and on smoking in the main stream and the side stream. 
     The perfume use of norbornene alcohol and ester derivatives having the structures: ##STR3## wherein R 1  is C 1  -C 4  alkyl is disclosed in U.S. Pat. No. 3,860,635 particularly at Example XV at column 16 thereof. Such compounds and the syntheses thereof are also disclosed by Bobyleva, Zh. Org. Kh. Volume 13, No. 10, pages 2085-92, October 1977. In addition, ethers of norbornene derivatives having the structures: ##STR4## are disclosed as well as the process for preparing same according to the reaction: ##STR5## in Shield, Can. J. Chem. Volume 49, 1971, page 1142. 
     U.S. Pat. No. 3,927,116 indicates the utility of certain vinyl norbornyl ethers having the structure: ##STR6## wherein R 2  represents C 1  -C 4  alkyl as being intermediate for the preparation of detergents at column 9 lines 10-15. No indication in U.S. Pat. No. 3,927,116 of the use of such compounds in perfumery, for augmenting or enhancing the aroma of perfumes, perfumed articles and colognes, is suggested either implicitly or explicitly in U.S. Pat. No. 3,927,116. 
     However, the compounds of our invention defined according to the structure: ##STR7## wherein R 1 , R 2  and R 3  represent methyl or hydrogen and at least one of R 1 , R 2  and R 3  is hydrogen have unexpected, unobvious and advantageous organoleptic properties in consumable materials over any closely similar compounds of the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is the GLC profile for the crude reaction product of Example I containing the compound having the structure: ##STR8## (conditions: 10&#39;×1/8&#34; SE-30 column programmed at 150°-220° C. at 6° C. per minute). 
     FIG. 2 is the NMR spectrum for Fraction 5 of the distillation product of the reaction product of Example I containing the compound having the structure: ##STR9## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 3 is the infra-red spectrum for Fraction 5 of the distillation product of the reaction product of Example I containing the compound having the structure: ##STR10## 
     FIG. 4 is the GLC profile for the crude reaction product of Example II containing the compound having the structure: ##STR11## 
     FIG. 5 is the NMR spectrum of Fraction 3 of the distillation product of the reaction product of Example II containing the compound having the structure: ##STR12## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 6 is the infra-red spectrum for Fraction 3 of the distillation product of the reaction product of Example II containing the compound having the structure: ##STR13## 
     FIG. 7 is the GLC profile for the crude reaction product of Example III containing the compound having the structure: ##STR14## (cis and trans isomer mixture). 
     FIG. 8 is the NMR spectrum for Fraction 10 of the distillation product of the reaction product of Example III containing the compound having the structure: ##STR15## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 9 is the infra-red spectrum for Fraction 10 of the distillation product of the reaction product of Example III containing the compound having the structure: ##STR16## 
     FIG. 10 is the GLC profile of the crude reaction product of Example IV containing the compound having the structure: ##STR17## 
     FIG. 11 is the NMR spectrum for Fraction 9 of the distillation product of the reaction product of Example IV containing the compound having the structure: ##STR18## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 12 is the infra-red spectrum for Fraction 9 of the distillation product of the reaction product of Example IV containing the compound having the structure: ##STR19## 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     In FIG. 1 which is the GLC profile for the reaction product of Example I containing the compound having the structure: ##STR20## the peaks indicated by reference numerals &#34;110&#34; and &#34;111&#34; are the peaks for the reaction product including the major reaction product (greater than 80%) which is the compound having the structure: ##STR21## but also including other compounds, for example, the compound having the structure: ##STR22## 
     FIG. 4 is the GLC profile of the crude reaction product of Example II which is indicated by peaks &#34;120&#34;, &#34;121&#34; and &#34;122&#34;. The major peak &#34;121&#34; is the peak for the compound defined according to the structure: ##STR23## The additional peaks &#34;120&#34; and &#34;122&#34; are for isomeric compounds including that having the structure: ##STR24## 
     FIG. 7 is the GLC profile for the reaction product of Example III containing a major proportion of the compounds having the structures: ##STR25## 
     The major peak &#34;131&#34; is for the compounds having the structures: ##STR26## Peaks &#34;130&#34; and &#34;132&#34; are for compounds which are in a minor proportion (20% or less) for example, the compounds having the structures: ##STR27## All of the compounds defined according to peaks &#34;130&#34;, &#34;131&#34; and &#34;132&#34; may be shown according to the genus having the structure: ##STR28## wherein one of the dashed lines represents a carbon-carbon bond and the other of the dashed lines represents no bond and wherein the wavy lines represent hydrogen and methyl groups juxtaposed around the carbon-carbon double bond in a &#34;cis&#34; or &#34;trans&#34; configuration. 
     FIG. 10 is the GLC profile for the reaction product of Example IV containing a major proportion (greater than 80%) of the compound defined according to the structure: ##STR29## The peak indicated by reference numeral &#34;141&#34; is the peak for this compound having the structure: ##STR30## The peaks indicated by reference numerals &#34;140&#34; and &#34;142&#34; are for compounds which are in a minor proportion (less than 20%) such as that having the structure: ##STR31## 
     THE INVENTION 
     It has now been determined that certain substituted norbornyl ester derivatives are capable of imparting a variety of flavors and fragrances to various consumable materials. Briefly, my invention contemplates augmenting or enhancing the flavors and/or fragrances of such consumable materials by adding thereto a small but effective amount of at least one such norbornyl ester derivative defined according to the generic structure: ##STR32## wherein R 1 , R 2  and R 3  represent methyl or hydrogen with the proviso that at least one of R 1 , R 2  and R 3  is hydrogen; and flavoring (e.g. for foodstuffs, chewing gum, chewing tobaccos, medicinal products and smoking tobaccos) and fragrance compositions (e.g. perfume compositions and compositions for augmenting or enhancing the aromas of perfumed articles such as solid or liquid anionic, cationic, nonionic or zwitterionic detergents or fabric softeners or fabric softener articles or cosmetic powders or hair preparations or perfumed polymers) containing such norbornyl ester derivatives. The invention also contemplates a novel process for producing such substituted norbornyl esters. 
     The norbornyl ester derivatives produced according to the process of my invention which are used in practicing that part of my invention concerning flavoring and fragrance compositions are actually racemic mixtures rather than individual stereisomers and mixtures of cis and trans isomers rather than individual cis or trans isomers (as the case may be). 
     The norbornyl ester derivatives of my invention insofar as their fragrance profiles are concerned have sweet, amber-like, powerful long-lasting green, herbaceous, floral (violet-like), fruity, powerful anisic and bergamot-like aromas. 
     Insofar as their flavor uses are concerned, (e.g. foodstuffs, chewing gums, medicinal products, toothpastes and chewing tobaccos), the norbornyl ester derivatives of my invention have sweet, licorice-like, anise oil-like, spicy, dill-like, fresh dandelion leaf, raw spinach and scallion-like aroma and taste nuances. 
     Insofar as smoking tobacco flavors and aromas are concerned, the norbornyl ester derivatives of my invention have Turkish tobacco-like aroma and taste nuances on smoking in both the main stream and the side stream and also prior to smoking. 
     The following table sets forth the structure and organoleptic property profiles for specific compounds produced according to the examples listed herein and located infra: 
     
                       TABLE I                                                     
______________________________________                                    
              Fragrance     Food Flavor                                   
Structure     Profile       Profile                                       
______________________________________                                    
 ##STR33##    Sweet, anisic, amber-like aroma with green, herbaceous top  
              notes.        A sweet, licorice-like, anise oil-like, spicy 
                            (dill- like) aroma and taste profile at 0.1   
                            ppm causing it to be useful for licorice,     
                            spearmint and mouthwash flavors.              
 ##STR34##    A powerful long-lasting green, herbaceous aroma.            
                            A fresh dandelion leaf, raw spinach aroma and 
                            taste with faint scallion-like nuances at     
                            0.01 ppm causing it to be extremely useful in 
                            salad dressing flavors.                       
 ##STR35##    A floral (violet- like), green, fruity aroma profile.       
                            A fresh dandelion-like, raw spinach- like     
                            aroma and taste profile at 0.3 ppm causing it 
                            to be extremely useful in salad dressing      
                            flavors.                                      
 ##STR36##    A powerful anisic, bergamot-like, fruity aroma with a       
              citronellal- like undertone.                                
                            A sweet, licorice-like aroma and taste        
                            profile at 0.001 ppm.                         
______________________________________                                    
 
    
     The compounds of my invention may be prepared by reacting ethylidene norbornene having the structure: ##STR37## with an acrylic acid derivative defined according to the structure: ##STR38## wherein R 1 , R 2  and R 3  may be hydrogen or methyl with the proviso that at least one of R 1 , R 2  and R 3  is hydrogen in the presence of a catalyst which is either a mineral acid or a Lewis acid. Examples of mineral acid catalysts are sulfuric acid, phosphoric acid, para-toluene sulfonic acid, methane sulfonic acid and acid ion exhange resins. Examples of Lewis acids which can be used as catalysts are boron trifluoride etherate, boron trifluoride, aluminum chloride, zinc chloride, stannic chloride, stannous chloride, zinc bromide, diethyl aluminum chloride, ethyl aluminum dichloride, ethyl aluminum dibromide and diethyl aluminum dibromide. The reaction preferably takes place in the presence of an inert solvent such as tetrahydrofuran, toluene or benzene. The reaction may take place in the absence of the inert solvent and in the presence of an excess of the acrylic acid derivative reactant, the excess of the acrylic acid derivative reactant being used as the &#34;solvent&#34;. 
     The reaction temperature may vary from about 25° C. up to about 120° C. with reflux temperatures being preferred. The reflux temperature depends on the pressure in the reactor and the particular solvent being used as well as its concentration in the reaction mass. The mole ratio of acid catalyst to ethylidene norbornene may vary from about 1:99 up to about 1:10. The mole ratio of ethylidene norbornene reactant to acrylic acid derivative reactant may vary from about 1:1 up to about 1:2 with a mole ratio of about 1:1 of norbornene:acrylic acid derivative reactant being preferred. Thus, the reaction to produce the compounds of my invention may be shown thusly: ##STR39## with the compound produced being the compound in greatest proportion (80% or more) in the reaction product mixture. The reaction in more general terms, however, may be shown thusly: ##STR40## wherein the wavy lines in the acrylic acid reactant structure and in the norbornyl ester derivative are indicative of a &#34;cis&#34; or &#34;trans&#34; juxtaposition of the R 1 , R 2 , R 3  and carboxylic acid moieties around the carbon-carbon double bond or the R 1 , R 2 , R 3  and carboalkoxy moieties around the carbon-carbon double bond. The term &#34;[K]&#34; represents the catalyst; that is, the Lewis acid catalyst or the protonic acid catalyst as set forth above. The dashed lines in the reaction product represent carbon-carbon bonds or no bonds. Thus, the reaction product which is shown according to the structure: ##STR41## in this more generalized equation represents compounds having the structure: ##STR42## (which is present in greater than 80% concentration) as well as the compounds having the structure: ##STR43## (which are present in less than 20% proportions in the reaction mass) (on a solvent-free basis). 
     Structures of these isomers are as follows: ##STR44## wherein R represents acrylyl, methacrylyl, crotonyl or senecioilyl. 
     The norbornyl ester derivative(s) and one or more auxiliary perfume ingredients, including, for example, hydrocarbons, alcohols, ketones, aldehydes, nitriles, esters other than said norbornyl ester derivatives, lactones, ethers, hydrocarbons, synthetic essential oils, and natural essential oils may be admixed so that the combined odors of the individual components produce a pleasant and desired fragrance, particularly and preferably in the amber, citrusy, anisic and floral fragrances. Such perfume compositions usually contain (a) the main note or the &#34;bouquet&#34; or foundation stone of the composition; (b) modifiers which round off and accompany the main note; (c) fixatives which include odorous substances which lend a particular note to the perfume throughout all stages of evaporation and substances which retard evaporation and (d) topnotes which are usually low-boiling, fresh-smelling materials. 
     In perfume compositions, it is the individual components which contribute to their particular olfactory characteristics, however, the overall sensory effect of the perfume composition will be at least the sum total of the effects of each of the ingredients. Thus, one or more of the norbornyl ester derivatives of my invention can be used to alter, modify or enhance the aroma characteristic of a perfume composition, for example, by utilizing or moderating the olfactory reaction contributed by another ingredient in the composition. 
     The amount of norbornyl ester derivative of my invention which will be effective in perfume compositions as well as in perfumed articles and colognes depends upon many factors including the other ingredients, their amounts and the effects which are desired. It has been found that perfume compositions containing as little as 0.005% of norbornyl ester derivative(s) or even less (e.g. 0.002%) can be used to impart sweet, amber-like, powerful long-lasting green, herbaceous, floral, violet-like, fruity, powerful anisic and bergamot-like aromas with citronellal-like undertones to soaps, cosmetics, detergents (including anionic, cationic, nonionic or zwitterionic solid or liquid detergents) perfumed polymers or other products. The amount employed can range up to 70% of the fragrance components and will depend upon the considerations of cost, nature of the end product, the effect desired on the finished product and the particular fragrance sought. 
     The norbornyl ester derivative(s) of my invention are useful (taken alone or taken together with other ingredients in perfume compositions) in detergents, soaps, space odorants and deodorants, perfumes, colognes, toilet waters, bath preparations, hair preparations such as lacquers, brilliantines, pomades and shampoos; cosmetic preparations such as creams, deodorants, hand lotions and sun screens; powders such as talcs, dusting powders, face powders and the like. 
     As little as 0.25% of the the norbornyl ester derivatives will suffice to impart an intense, sweet, amber-like, powerful long-lasting green, herbaceous, floral, fruity, powerful anisic, bergamot-like aroma to citrusy, floral, amber and anisic perfume formulations. Generally no more than 5% of the norbornyl ester derivative(s) based on the ultimate end product is required to be used in the perfume composition. 
     Furthermore, as little as 0.25% of the norbornyl ester derivatives will suffice to impart such aroma to perfumed articles per se, whether in the presence of other perfume materials or whether used by themselves. Thus, the range of use of the norbornyl ester derivative(s) of my invention in perfumed articles, e.g. perfumed polymers and solid or liquid anionic, cationic, nonionic or zwitterionic detergents, may vary from 0.25% up to about 5% by weight based on the total weight of the perfumed article. 
     In addition, the perfume composition or fragrance composition of my invention can contain a vehicle or carrier for the norbornyl ester derivative(s). The vehicle can be a liquid such as a non-toxic alcohol, e.g. ethanol, a non-toxic glycol, e.g. propylene glycol, or the like. The carrier can also be an absorbent solid such as a gum (e.g. gum arabic or xanthan gum or guar gum) or components for encapsulating the composition by means of coacervation (such as by gelatin) or by means of formation of a polymer around a liquid center (as by using a urea formaldehyde prepolymer to form a polymeric capsule around a perfume composition center). 
     It will be appreciated from the present disclosure that the norbornyl ester derivatives according to the present invention can be used to alter, vary, fortify, modify, enhance or otherwise improve the flavor of a wide variety of materials which are ingested, consumed or otherwise organoleptically sensed. 
     The terms &#34;alter&#34; and &#34;modify&#34; in their various forms will be understood herein to mean the supplying or imparting of a flavor character or note to an otherwise bland, relatively tasteless substance, or augmenting an existing flavor characteristic where the natural flavor is deficient in some regard or supplementing the existing flavor impression to modify their organoleptic character. 
     The term &#34;enhance&#34; is intended herein to mean the intensification (by use of the norbornyl ester derivative of my invention) of a flavor or aroma note or nuance in a tobacco flavor or foodstuff or perfume composition or perfumed article without changing the quality of said note or nuance. 
     A &#34;flavoring composition&#34; is taken to mean one which contributes a part of the overall flavor impression by supplementing or fortifying a natural or artificial flavor in a material or one which supplies substantially all the flavor and/or aroma character to a consumable article. 
     The term &#34;foodstuff&#34; as used herein includes both solid and liquid ingestible materials for man or animals which materials usually do, but need not, have nutritional value. Thus, foodstuffs include meats, gravies, soups, convenience foods, malt, alcoholic and other beverages, milk and dairy products, seafoods, including fish, crustaceans, mollusks and the like, candies, vegetables, cereals, soft drinks, snacks, dog and cat food, other veterinary products, and the like. The norbornyl ester derivatives of my invention are also useful tobacco flavorants and flavor enhancers. 
     The term &#34;tobacco&#34; will be understood herein to mean natural products such as, for example, burley, Turkish tobacco, Maryland tobacco, flue-cured tobacco and the like including tobacco-like or tobacco-based products such as reconstituted or homogenized leaf and the like as well as tobacco substitutes intended to replace natural tobacco such as lettuce and cabbage leaves and the like. The tobaccos and tobacco products in which the norbornylester derivatives of my invention are useful include those designed or used for smoking such as in cigarettes, cigar and pipe tobacco, as well as products such as snuff, chewing tobacco and the like. 
     When the norbornyl ester derivatives of this invention are used in a flavoring composition, they can be combined with conventional flavoring materials or adjuvants. Such co-ingredients or flavoring adjuvants are well known in the are for such use and have been extensively described in the literature. Requirements of such adjuvant materials are: (1) that they be non-reactive with the norbornyl ester derivatives of my invention; (2) that they be organoleptically compatible with the norbornyl ester derivatives of my invention whereby the flavor of the ultimate consumable material to which the norbornyl ester derivatives are added is not detrimentally affected by the use of the adjuvant; (3) that they be ingestibly acceptable and thus non-toxic or otherwise non-deleterious. Apart from these requirements, conventional materials can be used and broadly include other flavor materials, vehicles, stabilizers, thickeners, surface active agents, conditioners, and flavor intensifiers. 
     Such conventional flavoring materials include saturated fatty acids, unsaturated fatty acids and amino acids; alcohols including primary and secondary alcohols, esters, carbonyl compounds including ketons and aldehydes; lactones; other cyclic organic materials including benzene derivatives, allicyclic compounds, heterocyclics such as furans, pyridines, pyrazines and the like; sulfur-containing compounds including thiols, sulfides, disulfides and the like; proteins; lipids, carbohydrates; so-called flavor potentiators such as monosodium glutamate, magnesium glutamate, calcium glutamate, guanylates and inosinates; natural flavoring materials such as cocoa, vanilla and caramel; essential oils and extracts such as anise oil, clove oil and the like and artificial flavoring materials such as vanillin and the like. 
     Specific preferred flavor adjuvants are as follows: 
     anise oil; 
     ethyl-2-methyl butyrate; 
     vanillin; 
     cis-3-heptenol; 
     cis-3-hexanol; 
     trans-2-heptenol; 
     cis-3-heptenal; 
     butyl valerate; 
     2,3-diethyl pyrazine; 
     methyl cyclopentenolone; 
     benzaldehyde; 
     valerian oil; 
     3,4-dimethoxyphenol; 
     amyl acetate; 
     amyl cinnamate; 
     gamma butyryl lactone; 
     furfural; 
     benzaldehyde; 
     trimethyl pyrazine; 
     phenyl acetic acid; 
     isovaleraldehyde; 
     ethyl maltol; 
     ethyl vanillin; 
     ethyl valerate; 
     ethyl butyrate; 
     cocoa extract; 
     coffee extract; 
     peppermint oil; 
     spearment oil; 
     clove oil; 
     anethol; 
     cardamom oil; 
     wintergreen oil; 
     cinnamic aldehyde; 
     2,3-diethyl pyrazine; 
     ethyl-2-methyl valerate; 
     gamma hexenyl lactone; 
     2,4-decadienal; 
     2,4-heptadienal; 
     butylidene phthalide. 
     According to another aspect of my invention, an organoleptically improved smoking tobacco product and additives therefor as well as methods of making the same which overcome specific problems heretofore encountered in which specific Turkish, oriental-like aromas prior to smoking and improved Turkish, oriental aromas on smoking in the main stream and the side stream are created or enhanced or modified or augmented and may be readily controlled and maintained at the desired uniform level regardless of variations in the tobacco components of the blend. In particular, low grade Virginia-type tobaccos may be upgraded using the norbornyl ester derivatives of my invention. 
     This invention further provides improved tobacco additives and methods whereby various desirable natural aromatic Turkish tobacco flavoring characteristics with oriental notes may be imparted to smoking tobacco products and may be readily varied and controlled to produce the desired uniform flavoring characteristics. 
     In carrying out this aspect of my invention, I add to smoking tobacco materials or a suitable substitute therefor (e.g. dried lettuce leaves) an aroma and flavor additive containing as an active ingredient one or more of the norbornyl esters of my invention. 
     In addition to the norbornyl esters of my invention, other flavoring and aroma additives may be added to the smoking tobacco material or substitute therefor either separately or in admixture with the norbornyl ester derivatives of my invention as follows: 
     I. Synthetic materials: 
     Beta-ethyl-cinnamaldehyde; 
     Eugenol; 
     Dipentene; 
     Beta-damascenone; 
     Maltol; 
     Ethyl maltol; 
     Delta undecalactone; 
     Delta decalactone; 
     Benzaldehyde; 
     Amyl acetate; 
     Ethyl butyrate; 
     Ethyl valerate; 
     Ethyl acetate; 
     2-hexanol-1; 
     2-methyl-5-isopropyl-1,3-nonadiene-8-one; 
     2,6-dimethyl-2,6-undecadiene-10-one; 
     2-methyl-5-isopropyl acetophenone; 
     2-hydroxy-2,5,5,8a-tetramethyl-1-(2-hydroxyethyl)-decahydronaphthalene; 
     Dodecahydro-3a,6,6,9a-tetramethyl naphtho-(2,1-b)-furan; 
     4-hydroxy hexanoic acid, gamma lactone; and 
     Polyisoprenoid hydrocarbons defined in Example V of U.S. Pat. No. 3,589,372 issued on June 29, 1971. 
     II. Natural oils: 
     Celery seed oil; 
     Coffee extract; 
     Bergamot oil; 
     Cocoa extract; 
     Nutmeg oil; and 
     Origanum oil. 
     An aroma and flavoring concentrate containing one or more of the norbornyl ester derivatives of my invention and, if desired, one or more of the above indicated additional flavoring additives may be added to the smoking tobacco material, to the filter or to the leaf or paper wrapper. The smoking tobacco material may be shredded, cured, cased and blended tobacco material or reconstituted tobacco material or tobacco substitutes (e.g. lettuce leaves) or mixtures thereof. The proportions of flavoring additives may be varied in accordance with taste but insofar as enhancement or the imparting of oriental and/or Turkish tobacco notes, I have found that satisfactory results are obtained if the proportion by weight of the sum total of norbornyl esters to smoking tobacco material is between 50 ppm and 1,500 ppm (0.005%-0.15%) of the active ingredients to the smoking tobacco material. I have further found that satisfactory results are obtained if the proportion by weight of the sum total of norbornyl ester derivatives used to flavoring material is between 500 and 15,000 ppm (0.05%-1.5%). 
     Any convenient method for incorporating the norbornyl esters into the tobacco product may be employed. Thus, the norbornyl ester derivatives taken alone or along with other flavoring additives may be dissolved in a suitable solvent such as ethanol diethylether and/or volatile organic solvents and the resulting solution may either be spread onto the cured, cased, and blended tobacco material or the tobacco material may be dipped into such solution. Under certain circumstances, a solution of the norbornyl esters taken alone or taken further together with other flavoring additives as set forth above may be applied by means of a suitable applicator such as a brush or roller on the paper or leaf wrapper for the smoking product, or it may be applied to the filter by either spraying or dipping or coating. 
     Furthermore, it will be apparent that only a portion of the tobacco or substitute therefor need be treated and the thus-treated tobacco may be blended with other tobaccos before the ultimate tobacco product is formed. In such cases, the tobacco treated may have the norbornyl ester derivatives in excess of the amounts or concentrations above indicated so that when blended with other tobaccos, the final product will have the percentage within the indicated range. 
     In accordance with one specific example of my invention, an aged, cured and shredded domestic Virginia tobacco is spread with a 20% alcohol solution of the compound having the structure: ##STR45## produced according to Example I, infra, in an amount to provide a tobacco composition containing 100 ppm by weight of the compound having the structure: ##STR46## on a dry basis. Thereafter the alcohol is removed by evaporation and the tobacco is manufactured into cigarettes by the usual techniques. The cigarette, when treated as indicated, has a desired and pleasing aroma which is detectable in the main stream and the side stream when the cigarette is smoked. This aroma is described as being sweeter, with pronounced Turkish/oriental characteristics and with improved body and enhanced tobacco character in the main stream and side stream. In addition, interesting amber nuances are imparted. 
     While my invention is particularly useful in the manufacture of smoking tobacco such as cigarette tobacco, cigar tobacco and pipe tobacco, other tobacco products fromed from sheeted tobacco dust or fines may also be used. Likewise the norbornyl esters of my invention can be incorporated with materials such as filter tip materials, seam paste, packaging materials and the like which are used along with tobacco to form a product adapted for smoking. Furthermore, the norbornyl esters can be added to certain tobacco substitutes of natural or synthetic origin (e.g. dried lettuce leaves) and, accordingly, by the term &#34;tobacco&#34; as used throughout this specification, is meant any composition intended for human consumption by smoking or otherwise when composed of tobacco plant parts or substitute materials or both. 
     The following examples are given to illustrate embodiments of the invention as it is presently preferred to practice it. It will be understood that these examples are illustrative and the invention is not to be considered restricted thereto except as indicated in the appended claims. 
     EXAMPLE I 
     PREPARATION OF ACRYLIC ACID ESTER OF 5-ETHYL-TRICYCLO[2.2.1.0(2,6)]HEPTAN-1-OL 
     Reaction: ##STR47## 
     Into a 2 liter reaction flask equipped with stirrer, thermometer, heating mantle and reflux condenser is placed 30 ml borontrifluoride and diethyletherate and 300 ml anhydrous toluene. While maintaining the reaction mass at 25°-34° C., a mixture of 288 grams (4 moles) of acrylic acid and 480 grams (4 moles) of ethylidene norbornene are added to the reaction mass over a 35 minute period. The temperature over the 35 minute period is maintained at 25°-34° C. The reaction mass is then stirred at 25°-34° C. for a period of 20 minutes. 
     The reaction mass is then washed as follows: 
     i. 500 ml 10% aqueous sodium chloride 
     ii. two volumes of 10% sodium chloride 
     iii. 10% aqueous sodium chloride 
     iv. 500 ml 5% sodium hydroxide 
     v. 500 ml 10% aqueous sodium chloride 
     vi. 500 ml 10% aqueous sodium chloride. 
     The reaction mass is then dried over anhydrous magnesium sulfate and distilled on a 12&#34;×1.5&#34; Goodloe column yielding the following fractions: 
     
         ______________________________________                                    
         Vapor   Liquid                                                   
Fraction Temp.   Temp.     Pressure                                       
                                  Reflux                                  
Number   (°C.)                                                     
                 (°C.)                                             
                           mm/Hg. Ratio                                   
______________________________________                                    
1        41/44   72/117    50     2:1                                     
2        96      110       3      2:1                                     
3        82       97       3      2:1                                     
4        82      100       3      1:1                                     
5        83      100       3      100% takeoff                            
6        83      104       3      100% takeoff                            
7        82      130       3      100% takeoff                            
______________________________________                                    
 
    
     FIG. 1 is the GLC profile for the crude reaction product prior to distillation (conditions: 10&#39;×0.125&#34; SE-30 column programmed at 150°-220° C. at 6° C. per minute). 
     FIG. 2 is the NMR spectrum for fraction 5 of the foregoing distillation containing the compound having the structure: ##STR48## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 3 is the infra-red spectrum for fraction 5 of the foregoing distillation containing the compound having the structure: ##STR49## 
     EXAMPLE II 
     PREPARATION OF METHACRYLIC ACID ESTER OF 5-ETHYL-TRICYCLO[2.2.1.0(2,6)HEPTAN-2-OL 
     Reaction: ##STR50## 
     Into a 1 liter reaction flask equipped with stirrer, thermometer, reflux condenser and heating mantle is placed a mixture of 30 ml borontrifluoride diethyletherate and 285 grams of methacrylic acid. While maintaining the reaction mass at 20° C. over a period of 30 minutes, 340 grams of ethylidene norbornene is added with stirring. The reaction mass is then maintained at 15°-20° C. with stirring for a period of 1 hour. At the end of the 1 hour period, the reaction mass is quenched with 500 ml water. The organic layer is separated from the aqueous layer and the organic layer is washed as follows: 
     i. 10% aqueous sodium chloride 
     ii. 10% aqueous sodium hydroxide 
     iii. 3 volumes of 10% sodium chloride 
     The reaction mass is then dried over anhydrous magnesium sulfate and distilled on a 12&#34;×1.5&#34; Goodloe column to yield the following fractions: 
     
         ______________________________________                                    
          Vapor   Liquid                                                  
Fraction  Temp.   Temp.      Pressure                                     
                                    Reflux                                
Number    (°C.)                                                    
                  (°C.)                                            
                             mm/Hg. Ratio                                 
______________________________________                                    
1         25/85   89/100     2.0    5:1                                   
2         86      101        2.4    1:1                                   
3         84      102        2.4    1:1                                   
4         87      103        2.4    1:1                                   
5         87      107        2.4    1:1                                   
6         88      107        2.4    1:1                                   
7         86      105        2.4    1:1                                   
8         86      108        2.4    1:1                                   
9         86      110        2.4    1:1                                   
10        86      120        2.4    1:1                                   
11        86      130        2.4    1:1                                   
12        92      145        2.4    1:1                                   
13        92      180        2.4    1:1                                   
______________________________________                                    
 
    
     FIG. 4 is the GLC profile for the crude reaction product prior to distillation containing the compound having the structure: ##STR51## (conditions: SE-30 column programmed at 180° C. isothermal). 
     FIG. 5 is the NMR spectrum for fraction 3 of the foregoing distillation containing the compound having the structure: ##STR52## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 6 is the infra-red spectrum for fraction 3 of the foregoing distillation containing the compound having the structure: ##STR53## 
     EXAMPLE III 
     PREPARATION OF CROTONIC ACID ESTER OF 5-ETHYL-TRICYCLO[2.2.1.0(2,6)]HEPTAN-1-OL 
     Reaction: ##STR54## 
     Into a 3 liter reaction flask equipped with thermometer, stirrer, reflux condenser and heating mantle is placed a mixture of 300 grams of anhydrous toluene and 30 ml borontrifluoride etherate. While maintaining the reaction mass at 25° C., 344 grams of crotonic acid is slowly added. While maintaining the reaction mass at 25° C. and over a period of 1 hour, 480 grams of ethylidene norbornene is added to the reaction mass with stirring. 
     The reaction mass is then stirred for a period of 0.5 hours. At the end of the 0.5 hour period, 500 ml water is added to the reaction mass. 
     The organic layer is separated from the aqueous layer and the organic layer is washed as follows: 
     i. 500 ml 10% sodium carbonate 
     ii. water 
     The reaction mass is then distilled on a 12&#34;×1.5&#34; Goodloe column to yield the following fractions: 
     
         ______________________________________                                    
         Vapor   Liquid                                                   
Fraction Temp.   Temp.     Pressure                                       
                                  Reflux                                  
Number   (°C.)                                                     
                 (°C.)                                             
                           mm/Hg  Ratio                                   
______________________________________                                    
1        28/45   82/122    3      2:1                                     
2        102     130       3      2:1                                     
3        95      125       3      2:1                                     
4        94      128       3      2:1                                     
5        92      116       3      2:1                                     
6        94      130       3      100% takeoff                            
7        95      132       3      100% takeoff                            
8        96      140       3      100% takeoff                            
9        96      148       3      100% takeoff                            
10       96      148       3      100% takeoff                            
11       96      161       3      100% takeoff                            
12       98      201       3      100% takeoff                            
______________________________________                                    
 
    
     FIG. 7 is the GLC profile for the crude reaction product prior to distillation, containing the compounds having the structures: ##STR55## 
     FIG. 8 is the NMR spectrum for fraction 10 of the foregoing distillation containing the compounds having the structures: ##STR56## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 9 is the infra-red spectrum for fraction 10 of the foregoing distillation containing the compounds having the structures: ##STR57## 
     EXAMPLE IV 
     PREPARATION OF 3-METHYL CROTONIC ACID ESTER OF 5-ETHYL-TRICYCLO[2.2.1.0(2,6)]HEPTAN-1-OL 
     Reaction: ##STR58## 
     Into a 3 liter reaction flask equipped with stirrer, thermometer, reflux condenser and heating mantle is placed a mixture of 400 grams of senecioic acid (4 moles), 300 grams anhydrous toluene and 30 ml borontrifluoride diethyletherate. Over a 1 hour period, while maintaining the reaction mass at 25°-30° C., 480 grams (4 moles) of ethylidene norbornene is added to the reaction mass. The reaction mass is then stirred for 0.5 hours. 
     The reaction mass is then quenched with 1 liter of saturated sodium chloride solution. The aqueous phase is separated from the organic phase and the organic phase is then washed as follows: 
     i. One liter of 10% aqueous sodium carbonate 
     ii. One liter of sodium chloride 
     iii. 300 ml water 
     iv. One liter 10% sodium chloride. 
     The reaction mass is then dried over anhydrous magnesium sulfate and distilled on a 12&#34;×1.5&#34; Goodloe column yielding the following fractions: 
     
         ______________________________________                                    
        Vapor    Liquid                                                   
Fraction                                                                  
        Temp.    Temp.     Pressure                                       
                                   Reflux                                 
Number  (°C.)                                                      
                 (°C.)                                             
                           mm/Hg.  Ratio                                  
______________________________________                                    
1       76/30     80/100   15/3    100% take off                          
2       110      126       3       2:1                                    
3       104      122       3       2:1                                    
4       104      125       3       100% take off                          
5       110      127       3       100% take off                          
6       112      129       3       100% take off                          
7       112      129       3       100% take off                          
8       118      132       3       100% take off                          
9       118      135       3       100% take off                          
10      120      138       3       100% take off                          
11      122      138       3       100% take off                          
12      125      145       3       100% take off                          
13      125      148       3       100% take off                          
14      125      158       3       100% take off                          
______________________________________                                    
 
    
     FIG. 10 is the GLC profile for the crude reaction product of Example IV prior to distillation containing the compound having the structure: ##STR59## (conditions: SE-30 column programmed at 150°-220° C. at 8° C. per minute). 
     FIG. 11 is the NMR spectrum for fraction 9 of the foregoing distillation containing the compound having the structure: ##STR60## (Solvent: CFCl 3  ; Field strength: 100 MHz). 
     FIG. 12 is the infra-red spectrum for fraction 9 of the foregoing distillation containing the compound having the structure: ##STR61## 
     EXAMPLE V 
     TOBACCO FLAVOR FORMULATIONS 
     Cigarettes are produced using the following tobacco formulations: 
     
         ______________________________________                                    
Ingredients    Parts by Weight                                            
______________________________________                                    
Bright         40.1                                                       
Burley         24.9                                                       
Maryland       1.1                                                        
Turkish        11.6                                                       
Stem (flue cured)                                                         
               14.2                                                       
Glycerine      2.8                                                        
H.sub.2 O      5.3                                                        
______________________________________                                    
 
    
     At the rate of 0.2%, the following tobacco formulation is applied to all of the cigarettes produced with the above tobacco formulation: 
     
         ______________________________________                                    
Ingredients     Parts by Weight                                           
______________________________________                                    
Ethyl butyrate  0.05                                                      
Ethyl valerate  0.05                                                      
Maltol          2.00                                                      
Cocoa extract   26.00                                                     
Coffee extract  10.00                                                     
Ethyl alcohol (95%)                                                       
                20.00                                                     
H.sub.2 O       41.90                                                     
______________________________________                                    
 
    
     To portions of 50% of the cigarettes at levels of 10 and 20 ppm, the compound of Example IV having the structure: ##STR62## is added. These cigarettes are hereinafter called &#34;experimental&#34; cigarettes. The cigarettes without the compound of Example IV having the structure: ##STR63## are hereinafter called &#34;control&#34; cigarettes. The control and experimental cigarettes are then evaluated by paired comparison and the results are as follows: 
     a. In aroma, the experimental cigarettes are all found to be more aromatic with Turkish tobacco-like nuances. 
     b. In smoke flavor, the experimental cigarettes are all found to be more aromatic, more sweet with Turkish tobacco, oriental-like nuances than the control cigatettes. 
     The experimental cigarettes containing 20 ppm of the compound having the structure: ##STR64## are found to be fruity and have pleasant aesthetically pleasing licorice-like notes in addition. 
     EXAMPLE VI 
     GREEN SALAD DRESSING FLAVOR 
     The following flavor formulation is prepared: 
     
         ______________________________________                                    
Ingredients              Parts by Weight                                  
______________________________________                                    
    Black pepper oil             4                                        
    Nutmeg oil                   3                                        
    Celery oil                   3                                        
    Lemon oil                    3                                        
    Mustard oil                  1                                        
    Vinegar-citric acid (50:50 mixture)                                   
                                 120                                      
    Starch paste prepared from   300                                      
    tapioca flour-water (50:50 mixture)                                   
    Liquid egg yolks             210                                      
    Sodium chloride              7                                        
    Sucrose                      10                                       
    Mustard                      20                                       
    Locust bean gum              6                                        
    2-(2&#39;-n-butyl)-4,5-dimethyl  2                                        
    thiazoline prepared according to                                      
    Example III of U.S. Pat. No. 4,243,688                                
______________________________________