Study On The Enzymatic Regioselective Syntheses Of Glucose Tetraesters And The Law Of Pyrolytic Transformation In Cigarette Smoke

Glucose tetraesters occurred in tobacco were the important materials which had potential aroma or were the flavor precursors. Generally, they had no smell in cigarette, but they could give off organic acids (especially isobutylic acid, isovaleric acid, 2-methylbutylic acid and 3-methylvaleric acid) when cigarettes burning. They could improve the character of cigarette smoke taste and aroma, and also enhance the consistency of smoke taste and aroma. If glucose tetraesters were added to cigarette, the usage of sugar which mainly produced tar in cigarette could be decreased or eliminated, and thus the safety of cigarette could be improved. The very peculiar characteristic of structure made it very difficult to synthesize this kind of glucose ester, and the reports synthesized with practicality had not been seen before. The purpose of this research work was to research the method of regioselective syntheses of glucose tetraesters with enzymatic catalysis, to summarize the law of pyrolytic transformation in cigarette smoke and to study the functional effects and optional dosage in cigarette.A new selective synthetic route of 6-O-acetyl-2,3,4-tri-O-alkancarbonyl-D- glucopyranose with enzymatic catalysis was designed based on a number of domestic and overseas literatures which were searched systematically. The route was as follows: 6-O-acetyl-D-glucopyranose (â… ) was synthesized with the starting material of D-glucopyranose by enzymatic regioselective acylation. Then (â… ) was esterified with acyl chloride to get the pentaacetates of D-glucopyranose, which were hydrolyzed in C-1 position with enzymatic regioselective reaction to give the target products. Target products(â…¡,â…¢,â…£andâ…¤)were gotten for the first time by using enzymatic catalysis method at home and abroad through the synthetic research, which verified the new route designed to be a creative, effective and feasible one.The technological conditions of each step in the synthetic route were optimized, and the total yield percentages of target productsâ…¡,â…¢,â…£andâ…¤were 38.21%, 27.38%, 32.34% and 32.54%, respectively.Both the target products(â…¡,â…¢,â…£andâ…¤) and the interim products during the process of region-selective synthesis were characterized with the advanced technology of HRMS, IR, ¹HNMR, ¹³CNMRs and two dimensional NMR. The structures of those products were verified to be correct. And those products also had a high purity.The main pyrolytic outcome of target products(â…¡,â…¢,â…£andâ…¤) were isobutylic acid, isovaleric acid, 2-methylbutylic acid and 3-methylvaleric acid respectively through the analysis of Py-GC-MS.Pyrolytic transformation percentages in the particulate phases and the vapour phases of cigarette main stream smoke were quantitatively determined by smoke analytical experiments of pyrolytic products. The correlative coefficients of regressive equations for standardized curve of the main pyrolytic products including isobutyryl acid, isovaleric acid, 2-methylbutylic acid and 3-methylvaleric acid were 0.9993, 0.9994, 0.9997 and 0.9997, respectively. The percent recovery of those four organic acid in the particulate phase were 97.45%, 103.50%, 98.36% and 102.31%, respectively, while in the gaseous phase were 98.40%, 98.20%, 99.10% and 97.50%, respectively.Pyrolytic transformation percentages of the target products obtained from the main stream smoke were as follows: the total 14.32μg/mg(â…¡), 13.74μg/mg(â…¢), 13.73μg/mg(â…£) and 14.70μg/mg(â…¤); in particulate phases 12.49μg/mg(â…¡), 12.44μg/mg(â…¢), 12.90μg/mg(â…£) and 14.20μg/mg(â…¤), in vapour phases 1.83μg/mg(â…¡), 0.84μg/mg(â…¢), 1.29μg/mg(â…£) and 0.50μg/mg(â…¤). The results showed that the difference among the total pyrolytic transformation percentages of target materials (â…¡,â…¢,â…£andâ…¤) was not obvious (significant), the percentages in particulate phases were far higher than that in the vapour phases. In the vapour phases, the percentages of isobutyryl acid and 2-methylbutylic acid were higher than that of isovaleric acid and 3-methylvaleric acid.Application of the target products (â…¡-â…¤) in the cigarette was experimentally researched. The optimal dosages were 2.0ppm (â…¡), 1.5ppm (â…¢), 1.5ppm (â…£) and 1.5ppm (â…¤), respectively.Within the range of dosage, the target products (â…¡-â…¤) were able to obviously improve smoking taste of cigarette in the common function characteristics, and made the cigarette smoking taste mellowness, cleanness, strengthening sweet feeling, reducing the dry feeling. They could obviously soften cigarette smoke, and make cigarette flavor more delicateness, softness and longinquity. They could obviously decrease stimulation and cover up off-flavor. The pyrolytic transformation percentages of the target products and the application results of this study provided an academic base to industrial application.