Study On Synthesis Of 2-methyl Prrrole Compounds And Application In Cigarette

This paper studied the synthesis of 14 2-methyl pyrrole compounds by Paal-Knorr,esterification reaction and alkylation reaction,respectively.11 novel compounds were identified among these compounds.The optimized conditions of esterification reaction and alkylation reaction were also discussed and their structures of target compounds were confirmed by ¹H NMR,¹³ C NMR,IR and HRMS.Then the thermolysis of target compounds was experimented and the flavoring application of them into cigarette was researched as well.The results were shown as below:1.In alkaline condition,glucosamine hydrochloride,acetyl acetone and ethyl acetoacetate as the raw material,were performed by heating reflux in aqueous solution,standing for about 24 h at low temperature after reaction,precipitating white matter and pump filtration.Then the filtrate was operated by acetone recrystallization to get the solid product 2a?2-methyl-3-acety-5-1'2'3'4'-tetrahydroxylbutyl-pyrrole?and 2b?2-methyl-5-1'2'3'4'-tetrahydroxylbutyl-3-pyrrole ethyl formate?.Sodium periodate as oxidant and methanol as solvent were carried by heating reflux at 40? to get two higher-yield products: 3a?2-methyl-3-acetyl-5-formyl pyrrole?and 3b?2-methyl-5-formyl-3-pyrrole ethyl formate?.In alkaline condition,with tetrabutyl ammonium bromide as phase transfer catalyst,3a reacted with bromopentane,bromoisopentane,bromoisopropane and bromoisobutane,respectively to produce nine novel N-substituted compounds,coupled with the another process of 3b reacting with both the same four matters and bromopropane.2.3b,aniline,p-toluene sulfonic acid as the catalyst and a certain amount of rongalite?sodium hydrosulfite?was run by electromagnetic stirring in the oil bath pot,heating reflux for 4 h at 65?,filtering and drying.Then anhydrous methanol was added to recrystallize to generate beige solid?6?;Next,anhydrous ethanol as solvent,Na BH4 as reductant and 6 were stirred at room temperature for 8 h.The mixture was concentrated and added with ethyl acetate and water in order to separate organic phase as well as to extract the left water layer with ethyl acetate.Ester layer was merged,washed by saturated sodium chloride solution,dried by anhydrous sodium sulfate,filtered and boiled away.Residue and methanol were by recrystallization to get white solid?7?.Two novel compounds were produced in this synthetic route.3.2,5-hexanedione and amino acid as raw materials were experimented by Paal-Knorr reaction to synthesize two N-2,5-dimethyl pyrrole derivatives.N-2,5-dimethyl pyrrole leucine as raw material was by esterification with benzyl alcohol and benzene ethanol,respectively.Meantime,N-2,5-dimethyl pyrrole glycine experienced the same reaction.In the two experiments,the effect of different catalysts,different solvents and varied reaction temperatures on esterification reaction was compared,consequently,the optimized condition for esterification reaction was identified: esterification reaction was operated by stirring anhydrous acetonitrile as solvent at room temperature in DMAP/EDC system.Three pyrrole compounds were generated in this route.4.As the representative,4a,4b,4c,4d,5a,5b,5c,5d and 5e were tested by TG-DTG-DSC to study thermal decomposition kinetics and the rule of mass weightlessness variation;simultaneously,4a,4b,4c,5b,5c,5d,6 and 7 were probed by thermal cracking to analyze their behaviors at 300?,600? and 900?,together with their principles of thermal cracking.As the results show,the majority of compositions present aroma from the pyrolyzing products.Thus,not only the fragrance of cigarette per se can be smoothed out,but also its smoking feeling can be increased.These substances can improve cigarette taste and provide unique aroma of the cigarette.Both 6 and 7 have the smaller proportion of scent matters,but the hazardous products and other impurities occupied the bigger proportion.5.For pyrrole compounds?4a,4b,4c,4d,5a,5b,5c and 5d?,the volume and quality of aroma,smoothness,softness,mellow,dry sensation and aftertaste from varied concentration of the smoke have improved,compared to the control group.With an increase of the concentration of additives,offensive odor and irritation of?4a,4b,4d,5a,5c and 5d?rose.For?4c?,when the dosage was 0.09‰,the volume and quality of aroma,offensive odor,penetration,smoothness,mellow,dry sensation and aftertaste of the smoke would more significantly improve than the control.Therefore the improved smoke was more smooth,mer and comfortable.For?5b?,when the dosage was 0.06‰,the feature of aroma has significantly improved,offensive odor and irritation had some reduction,compared to the control group.The quality of smoking also had obvious improvement coupled with its strength,combustibility and gray having small fluctuation.However,the whole flavoring effect is not obvious for?6 and 7?.Instead,sometimes this treatment of additives can lower the quality of cigarette.Considering the whole evaluation of smoking,the sense quality of?5b?is the best when the dose is 0.06‰.The sense quality of?4c?is the best when the dose is 0.09‰.