The Synthesis Of α,β-unsturated Ketones And Unsaturated Carboxylic Diacids And Their Application In Cigarette

α,β-unsaturated ketones and unsaturated carboxylic diacids, for example, verbenone,3-oxo-ionone,4-oxo-ionone,4-oxo-methyl-ionone, 4-oxo-damascone,p-methoxyl cyanocinnamic diacid, p-methyl cyanocinnamic diacid, cyanocinnamic diacid etc. are often the important flavors in the fields of flavor industry. Especially, they can increase significantly flavour in the low tar cigarette.In this article, a series of tobacco flavorants ofα,β-unsaturated ketones and cyanocinnamic diacids were synthesized by allylic oxidation of alkenes and the Knoevenagel condensation of aromatic aldehyde. The obtainedα,β-unsaturated ketones and unsaturated carboxylic diacids were well identified by 1HNMR and FT-IR spectra. Furthermore, theα,β-unsaturated ketones and unsaturated carboxylic diacids were be added into cut filler and cigarette paper to test the effects of increasing the cigarette flavor, which showed great interesting in tobacco industry.This article consists of three parts. In the first part, we briefly reviewed the recent progress on the synthesis of tobacco flavorants, especially the synthesis methods of allylic oxidation and Knoevenagel condensation.In the second part, the synthesis ofα,β-unsaturated ketones by the allylic oxidation of alkenes in the presence of Co(acac)2 catalyst with t-BuOOH as oxidant was investigated. Verbenone,3-oxo-ionone, 4-oxo-ionone,4-oxo-methyl-ionone as well as 4-oxo-damascone were synthesized by a-pinene,3-ionone,4-ionone,4-methyl-ionone,4-damascone, respectively. Under the optimum reaction conditions, the yields of the aboveα,β-unsaturated ketones were as high as 35%-53%. The mechanism of allylic oxidation of alkenes were proposed. The resultantα,β-unsaturated ketones were be added into cut filler and cigarette paper for testing the cigarette flavor. The results showed that all of the flavor compounds of a,β-unsaturated ketones, especially the 4-oxo-damascone, could improve the flavor quality of the cigarette and reduced the offensive taste and irritancy of smoke, such as aroma quality, aroma content, abundance and exquisiteness of the cigarette. The transfer behavior of 4-oxo-damascon in the cigarette smoke was studied. The results showed that 4-oxo-damascone as the falvor composition contributed to the mainstream smoke during burning process.In the third part, the Knoevenagel condensation of aromatic aldehyde for the synthesis of p-methoxyl cyanocinnamic diacid, p-methyl cyanocinnamic diacid and cyanocinnamic diacid under microwave irradiation and conventional heat with no solvent were investigated. Under the optimum reaction conditions of 10 mmmol aromatic aldehyde, 1.4 M ammonium acetate, irradiated in microwave oven at power of 365 W for 5 min, good yields of the corresponding diacids could be obtained. The resulting unsaturated carboxylic diacids were added into cut filler and cigarette paper for testing the cigarette flavor. The results indicated that the unsaturated carboxylic diacids could enrich the tobacco flavor, reduce the irritancy of smoke and improve the taste. The transfer behavior of cyanocinnamic diacid in the cigarette smoke was studied. The results showed that the flavoring effect of cyanocinnamic diacid was contributed to the formation of cyanocinnamic acid during the cigarette buring process.