Flavor additives have long been used to flavor a wide variety of consumer products, particularly tobacco products, foodstuffs, and gums. Flavor additives in such products may be used to mask or attenuate undesirable flavors or odorants, and to enhance existing flavors or odors, or to provide additional flavors or odors not initially present in the consumer product.
In tobacco and tobacco products, flavorants have been added in order to modify or enhance the overall flavor of the product upon use, primarily during smoking. However, the use of many flavorants in tobacco is limited by the volatility or stability of the particular flavorant. Consequently, there is a need for flavorants to be incorporated into tobacco products in such a manner that the flavorant is stable and nonvolatile but then will be released during use. Sylvamber (a Givaudan-Roure trade name for dodecahydro-3a,6,6,9a-tetramethylnaphtho 2,1-B!furan, CAS#6790-58-5) has long been used in fragrances to provide a strong woody amber note. Sylvamber has been reported to be a component of French Tobacco Absolute, B. Corbier, C. Ehret, E. Giraudi and G. Pelerin (Flavors and Fragrances: A World Perspective, Proceedings of the 10th International Congress of Essential Oils, Fragrances and Flavors , B. M. Lawrence, B. D. Mookerjee and B. J. Willis (editors), p. 483-494, Elsevier Science Publishers, Amsterdam, 1988). Sylvamber has also found occasional use as a tobacco flavorant. The utility of Sylvamber, however, is limited by its low odor threshold and its volatility. When used at levels high enough to have a strong impact upon smoking, Sylvamber tends to volatilize from the cigarette into the surrounding pack. In addition, Sylvamber imparts an odor to the unsmoked cigarette which is not acceptable to many smokers.
A principal strategy currently employed to impart flavors and odors to consumer products is admixing the flavorant chemical within a matrix that slows or prevents its release until the product is pyrolyzed, heated, masticated, or wetted. For example, European patent no. 186,502 describes the use of a plastic capsule that releases flavorants when mechanically crushed.
U.S. Pat. No. 4,001,438 describes flavor compositions for use in oral compositions which may be chewing gum compositions, chewable medicinal tablets, chewing tobacco, or toothpaste. The flavor is controllably released from a matrix of solid particles and a suspending agent over an extended period of time under hydrolyric conditions.
U.S. Pat. No. 4,253,473 describes smoking tobacco or substitute smoking tobacco compositions which upon smoking release a flavor from a matrix of solid particles and a suspending agent over an extended period of time.
U.S. Pat. No. 3,818,107 describes a chewing gum containing a flavor release composition comprising flavor groups appended to polymer backbones. The flavor moieties are released from the polymer backbone by hydrolysis during mastication of the chewing gum.
As an alternative method to impart flavors and odors to consumer products, flavoring chemicals have been covalently bound to an auxiliary component to form a higher molecular weight molecule of low volatility. The flavorant is released upon pyrolysis, heating, or solvolysis of the tobacco or food product. For example, U.S. Pat. Nos. 4,701,282 and 4,538,627 describe the use of .beta.-hydroxy-gamma-keto esters as flavorant additives which pyrolyze to release flavorants under cigarette smoking conditions to enhance the flavour of the mainstream smoke and the aroma of sidestream smoke.
U.S. Pat. Nos. 4,690,157 and 4,607,118 describe tobacco compositions containing flavor release additives which pyrolyze in a "retro-aldol" fragmentation reaction into products which enhance the flavor and aroma of cigarette smoke.
U.S. Pat. Nos. 4,578,486 and 4,538,628 describe tobacco compositions which contain dioxane diester flavorant-release additives. When subjected to smoking conditions, the diester additive pyrolyzes to release a volatile alcohol or phenol component which provides flavor-enhancing properties to the mainstream smoke and enhances the aroma of the sidestream smoke.
U.S. Pat. No. 4,872,918 describes a heterocyclic ester which releases tetramethylpyrazine and an olefin upon pyrolysis to improve the flavor and aroma of mainstream and sidestream smoke.
U.S. Pat. No. 2,905,575 describes the use of .alpha.-hydroxy-2,5,5,8a-tetramethyl-1-naphthaleneethanol (sclareol diol) in tobacco to impart a cedar-like aroma to the mainstream smoke. Sclareol diol is odorless when pure and presumably loses a molecule of water during smoking to yield the odorant molecules.
The use of sclareol diol in tobacco, however, presents some drawbacks. Upon smoking, cigarettes containing sclareol diol possess some off-notes not characteristic of Sylvamber. In addition, the effectiveness of sclareol diol declines significantly after one to two months on the cigarette.
Esters of sclareol diol (rather than carbonates) are known compounds. The acetate is not a crystalline solid (W. Herz et. al, J. Org. Chem., 42, 806-813 and K. Mori et. at., Liebigs Ann. Chem., 361-368, 1990), but the epimeric acetate, however, (see structure 14b in G. Ohloff et. al., Helv. Chim. Acta, 72, 1935-1947, 1990) is a solid. Precursor molecules which are not solids are generally not useful as flavorants because they are very difficult to obtain pure. In addition, upon pyrolysis, ester derivatives will release the corresponding carboxylic acids which in many cases will have a serious affect upon the flavor.
Accordingly, the present invention provides novel crystalline alkyl carbonate derivatives of sclareol diol which are odorless and stable to storage under ambient conditions but are useful as tobacco flavorants under normal smoking conditions. The present invention also provides smoking compositions, and methods for flavoring smoking compositions, which incorporate the novel alkyl carbonate derivatives of sclareol diol of the invention.