Synthesis Of New Pyrrolates Flavor Compounds And Their Application In Cigarette

As pyrrole derivatives are abundantly present in natural goods,researchers and aroma chemists are very interested in learning more about their distinctive structural features and scent.There is an urgent need to find pyrrole type macromolecular aromatic substances that are more convenient to synthesize,have a more unique aroma,and have more stable properties due to its low boiling point and strong volatility.In this project,glucosamine hydrochloride,which is easily accessible and found in natural products,was chosen as the raw material to design and synthesize a series of new pyrrolidine ester compounds.The research for this article is mostly divided into three sections:1.5-Pyrrolidine methyl ester derivatives and 5-Pyrrolidine carboxylic acid ester derivatives synthesisSix intermediates of Methyl 3-pyrrole(4a-4f)were produced in three phases of oxidation,cyclization,and substitution utilizing glucosamine hydrochloride as the starting material to create 5-Pyrrolidine derivatives.These were then converted to 5-Hydroxypyrrole(compound 5)by reducing compound 4a with Na BH4.Then esterification reaction was carried out of compound 5 with two aromatic acids(2-methylbutyric acid and benzoic acid)using EDC and DMAP,two 5-pyrrolidone derivatives(6a and 6b)were created.The structures of five novel pyrrole intermediates and two novel 5-Pyrrole carboxylates were characterized by nuclear magnetic resonance,infrared spectroscopy,and mass spectrometry.Six pyrrolecarboxylic acid derivatives(7a-7f)were oxidized in acetone solution utilizing six pyrrolecarboxylic acid intermediates(4a-4f)as raw materials and KMn O4 as an oxidant in order to create 5-Pyrrolecarboxylic acid ester derivatives;26 distinct alcohol compounds were esterified with EDC and DMAP using 7a as the starting material to create26 5-Pyrrolecarboxylic acid esters(8a-8z).Three 5-Pyrrolecarboxylic acid derivatives(7a-7c)were esterified with glycerol at the same time to create three polyol pyrrolates(8za-8zc).29 new 5-Pyrrolecarboxylic acid esters in all were created.The structures of 6novel 5-Pyrrolecarboxylic acid compounds and 29 5-Pyrrolecarboxylic acid esters were characterized by nuclear magnetic resonance,infrared spectroscopy,and mass spectrometry.2.Research on target compounds’ smell assessment and thermal behaviorUsing an olfactory evaluation system,43 target compounds were produced in order to screen 3-Pyrrolidine methyl ester derivatives with distinctive scent,relative stability at room temperature,and outstanding thermal behavior.The findings demonstrated that 10 target compounds(6a,6b,8a,8d,8h,8i,8s,8x,8y,and 8z)possessed features of fruit,caramel,and milk aromas and worked well with tobacco fragrance.In order to further study the thermal stability and behavior of these 10 flavor compounds,the thermal decomposition processes and pyrolysis products in the presence and absence of oxygen were studied using a thermogravimetric analyzer and a Py-GC-MS instrument,respectively.The results showed that the mass loss stages of 5-Pyrrolidone derivatives(6a,6b)in the absence of oxygen were 134.0~400.0 ℃(6a),208.0~450.0 ℃(6b),respectively.The mass loss stages of 5-Pyrrolecarboxylate derivatives(8a,8d,8h,8i,8s,8x,8y,8z)in air atmosphere were 155.4 to 450 ℃(8a),206.3 to 346.4 ℃(8d),233.6 to400 ℃(8h),203.6 to 368.7 ℃(8i),180 to 450 ℃(8s),158.2 to 400 ℃(8x),203 ℃ to 450℃(8y),and 217 to 450 ℃(8z).Indicating that these compounds have good thermal stability at low temperatures and can essentially be completely degraded before 450 °C,the degradation rate of all samples is above 80%.2-Methylbutyric acid,2-Methylpyrrole,benzoic acid,and other compounds were produced during the pyrolysis of 5-Pyrrolidinyl ester derivatives 6a and 6b at 300 and 300-900 °C in an oxygen-free environment.The pyrolysis products of eight 5-Pyrrolecarboxylic acid derivatives(8a,8b,8h,8i,8s,8x,8y and 8z)under aerobic conditions at 300,350,and 400 ℃ include ethyl maltol,menthol,vanillin,citronellol,phenylethanol,4-Pyridylmethanol,and 2-Methylpyrrole.The target compounds’ pyrolysis byproducts are made up of the raw ingredients used in their synthesis.The food and tobacco industries both make extensive use of the pyrolysis products,which have distinct scent characteristics.3.Application of representative products of novel pyrrolidine ester compounds in tobaccoRepresentative new pyrrolidine ester compounds 6a,8a,and 8h with pronounced scent characteristics,outstanding thermal stability,and thermal behavior were chosen for cigarette flavoring applications in order to examine the flavoring impact and the ideal amount of new pyrrolidine ester compounds in cigarettes,take representative polyol pyrrolate compounds8 y and 8z for water retention study.The results indicate that 0.8 ppm is the most appropriate addition quantity for samples 6a,8b,and 8h based on all smoking assessment markers,and the best way to add 8a and 8b is to add aroma to cigarette paper.This amount is generally consistent with the aroma of tobacco and has a high level of richness.The smoke is mellow,the pollutants,irritation,and dryness are reduced,the aftertaste is long and generally comfortable,and all of these factors contribute to an increase in the sensory comfort of cigarette smoking;The cut tobacco added with 8y and 8z has moisture retention effect,and can properly reduce the strong moisture absorption of traditional humectant.