Study On Synthesis Of Nitriles As Flavors And Application Of Related Synthetic Method

The application of aldehydes as odorants is often limited due to their relatively chemical activity,especially in certain acidic or alkaline matrix.The nitriles are relatively stable and are ideal substitutes for aldehydes.Based on the method of preparing nitrile by dehydration of aldehyde oxime developed in our previous work,a series of aldehydes as fragrances or flavors were used as starting materials to synthesize the corresponding nitriles using dimethyl sulfoxide / oxalyl chloride combination reagent.The obtained products were subjected to odor evaluation to search for valuable fragrances or flavors.In addition,on the basis of our previous work,this thesis investigated the sulfochlorination reaction of olefins with dimethyl sulfoxide / oxalyl chloride,and further expanded the application of the combined reagent dimethyl sulfoxide / oxalyl chloride in organic synthesis.The thesis first accomplished the preparation of a series of nitriles.Starting with 20 aldehydes as fragrances or flavors,including saturated aliphatic aldehydes,conjugated or non-conjugated aldehydes,unsaturated aldehydes,aliphatic aldehydes containing aromatic rings and aromatic aldehydes,aldoximes were formed by reactions with hydroxylamine hydrochloride in the presence of triethylamine and then underwent dehydration by treatment with a catalytic amount of dimethyl sulfoxide and oxalyl chloride,to produce the corresponding nitriles.The results indicated that long-chain aliphatic aldehydes gave the corresponding nitriles in high yields,and the products usually did not require purification.Among all the products,the yield of trans-2-hexenenitrile is the lowest,and the yields of most products exceeded 80%.The functional groups of unsaturated double bonds or hydroxyl groups in the substrates were not affected in the dehydration reaction,indicating that this method has good functional group compatibility.The odor characteristics of the obtained nitriles were evaluated and analyzed by GC-MS-O.The results of the odor evaluation indicated that most of these nitriles have different odor characteristics compared with the corresponding aldehydes,four of the long-chain aliphatic nitriles have a sweet,fruity or melon-like odor,and N-decanonitrile and N-undecanonitrile presents a unique cilantro odor,nitriles presents a milder odor,with a pleasant aroma such as sweet aroma,fruity aroma,coriander and almond-like odor.In view of the stability of nitriles,these nitriles are expected to become truly practical fragrances or flavors.This thesis also studied the sulfochlorination of olefins with dimethyl sulfoxide /oxalyl chloride.The sulfochlorination of terminal olefins and cyclic olefins by treatment of dimethyl sulfoxide / oxalyl chloride combination reagents were investigated respectively.The terminal olefins mainly produced Markovnikov adducts,while the cyclic olefins afforded adducts with trans configuration.These results further verified the existence of the active intermediate of methanesulfenyl chloride proposed earlier in our work.Dimethyl sulfoxide / oxalyl chloride can be used as an ideal reagent for sulfochlorination of olefins.It can be concluded that dimethylsulfoxide / oxalyl chloride are effective reagents for the dehydration reaction of a series of aldoximes to prepare the corresponding nitriles.This method is convenient and practical,the reagents are easily available and the conditions are mild.The combined reagent is used in the sulfochlorination of olefins and can synthesize1,2-chloromethylthio-containing compounds as a useful intermediate in organic synthesis.The research work of this thesis has certain reference value for the development of new fragrances or flavors.