The Synthesis Of The Precursors Of δ-damascone And δ-methyldamascone And The Application In Cigarettes

Damascones have floral, musty, hay-tea-like, sweet and fruity notes which are desirable in tobacco flavoring compositions and substitute tobacco flavoring compositions. A limited amount of such materials that give rise to these properties is available from natural sources but the natural materials are subject to wide variations in quality, are expensive. Too low threshold of damascones leads to a fluctuation of cigarettes quality. Hence, there is a need for the development of these compounds instead of damascones using in tobacco compositions .Penta- 1, 3 - diene, a cheap petroleum chemical products, and mesityl oxide, as starting materials, 3-Hydroxy-l-(2, 6, 6-trimethyl-3-cy-Clohexen-l-yl)-l-butanone and 3-Hydroxy-l-(2, 6, 6-trimethyl-3-cyclo-hexen-l-yl)-l-pentaone were prepared and characterized by GC-MS , 1HNMR and 13CNMR .First, 4-acetyl-3, 5, 5-trimethylcyclohexene was prepared by Diels-Alder cycloaddition of penta- 1, 3 - diene and mesityl oxide. The influences of the concentration of penta- 1,3- diene on the yield of the product was studied, and the isolation method of the product such as the steam distillation time, whether adding the liquid paraffin or not were studied as well.Then, 1-(2, 6, 6- trimethyl -3- cyclohexen-1-y1)-1, 3-butandione and 1-(2, 6, 6- trimethyl -3- cyclohexen-l-yl)-1, 3-pantadione were prepared by condensation of the 4-acetyl-3, 5, 5-trimethylcyclohexene with ethyl acetate and ethyl propionate respectively. On the process of synthesis of 1-(2, 6, 6- trimethyl -3- cyclohexen-l-yl)-1, 3-butandione, the temperature of the reaction was examined . While on the process of preparation of 1-(2, 6, 6- trimethyl -3- cyclohexen-l-yl)-1, 3-pantadione, the yield of the product can be increased obviously if ethanol, one of the product of the reaction, was removed from the reaction mixture by simultaneous distillation.3-Hydroxy-1-(2,6,6-trimethyl-3-cyclohexen-1-yl)-1- butanone and 3-Hydroxy-1 -(2,6,6-trimethyl-3-cyclohexen-1-y1)-1 -pentaone were synthesized by the reduction of corresponding dione with sodium borohydride respectively. It was discovered that the amount of sodium borohydride and the reaction time have influenced on the yield of the product. 3-Hydroxy-1-(2, 6, 6-trimethyl-3-cyclohex-en-1-yl)-1-pentaone is a novel compound.To evaluate their effects on cigarettes smoke, 3-Hydroxy-1-(2, 6, 6-trimethyl-3-cyclohexen-1-yl)-1-butanone and 3-Hydroxy-1-(2, 6, 6-trimethyl-3-cyclohexen-1-yl)-1-pentaone were added into cigarettes. The smoke extract of the cigarettes was analysed by GC-MS. The results of the sensory evaluation of cigarettes were obtained as well. It was found that the two compounds could be pyrolyzed to produce 5 -damascone and 5 -methyldamascone in tobacco smoke upon smoking respectively. When the said compounds added into tobacco, the amount of 5 -damascone or 5 -methyldamascone in tobacco smoke decrease more slowly than that of 5 -damascone does for a long time. The cigarettes with addition of the synthesized precursors were found to have more body in tobacco smoke flavor and a fuller sensation. The tobacco-like notes are enhanced and the flavor of the tobacco on smoking is more aromatic with floral, musty, hay-tra-like, sweet and fruity aroma.