Preparation Of New Furan And Indole Flavours And Their Effect On Cigarette Flavoring

As the intermediate products of Maillard reaction,heterocyclic compounds are an important kind of characteristic aroma substances and play an important role in cigarette flavor application.Manganese is an abundant transition metal element in the earth crust,for a long time,manganese complexes have been widely applied in catalytic oxidations and coupling reactions.In order to further explore the new catalytic functions of manganese element and develop the new synthesis method of nitrogen-containing and oxygen-containing heterocyclic aromatic compounds,we developed a series of pincer manganese catalysts.With the unique mechanism of outer-sphere hydrogen transfer,24 kinds of carbonyl furan derivatives were synthesized with furfuryl alcohols and carbonyl compounds and 31 kinds of indole compounds were synthesized from indole and alcohol compounds.Among of those products,including 11 kinds of new carbonyl furans and 3kinds of indole compounds.The thermal properties of furans and indole flavor compounds with representative aromas were studied and the application tests of cigarette flavoring were carried out.This study provides a new way for the efficient synthesis,development and utilization of novel furan and indoles flavor compounds.The specific research results are as follows:1.Manganese-catalyzed dehydrogenative coupling of furfuryl alcohols with carbonyl compounds to form carbonyl furan derivatives.Using furfuryl alcohol and aldehyde or ketone carbonyl compounds as raw materials,24 kinds of carbonyl furfuran flavoring compounds were developed with up to 90% yield under the action of manganese catalyst.In this reaction system,the base metal manganese catalyst is used for the first time,and the by-product is only water,which has the advantages of high efficiency,high selectivity and good substrate universality.The typical aroma compounds are pyrolyzed to release a range of flavor compounds,Including with sweet and flue-cured flavor of pyridine,like burley smoke flavor and can enhance the richness of smoke 2-methylpyridine,green sweet and fragrant 2-ethylpyridine,popcorn aroma of 2-acetyl pyridine,often as a spice of 2-pyridine formaldehyde,aromatic thiophene,herbal fragrance of 2-methylthiophene,boiled shrimp flavor of 2-thiophene formaldehyde,coffee aroma of 2-acetyl thiophene,etc.,Among them,alkyl pyridines,2-methylthiophene and 2-acetyl thiophene aroma compounds can improve the flavor of cigarettes,and enhance the richness of cigarette aroma,in order to provide theoretical reference for cigarette aroma application.2.Manganese-catalyzed the efficient synthesis of C3-alkylated and alkenylated indoles by dehydrogenation coupling of indoles with alcohols.A series of C3-alkylated and alkenylated indoles were synthesized from indole compounds and benzyl alcohols or 2-arylethanols by dehydrogenation coupling catalyzed by manganese complex with good to excellent yield(up to 99%).The characteristics of this method are cheap and easy to obtain raw materials,green environment protection,high atomic economy,good universality of substrate and high selectivity.The thermal cracking of representative aroma compounds under high temperature conditions can produce jasmine,rose,nut,popcorn,caramel and other characteristic aroma substances that can effectively improve the smoking quality of cigarettes.3.Study on flavoring effect of furan and indole flavor compounds in cigarette.Carbonyl furan and indole compounds with representative aroma were selected to study the flavoring effect of cigarette.The smoking evaluation results showed that: The optimum concentrations of carbonyl furan compounds 3e,3f,5f,5g,5i and 5j in single feed tobacco are 25mg/kg,15mg/kg,15mg/kg,5mg/kg,15mg/kg and 25mg/kg,respectively.The optimum concentrations of indole compounds for 10 k,12a and 12 h in single feed tobacco were 0.3mg/kg,0.5kg/kg and 0.3mg/kg,respectively.The results of cigarette aroma evaluation test showed that different target compounds had positive effects on cigarette smoking evaluation quality when the optimal dosage was added,which mainly showed that the aroma was sufficient,the aroma was good,the strength was strong,the irritation and impurity were significantly reduced,the aftertaste was clean and had a sweet feeling.