Study On The Preparation Of Alpha-damascenone

Alpha-damascenone because of its special rose,fruit and delicate fragrance,it is a rare spice developed in recent decades,flavoring agent used in the high-end cosmetics and cigarettes,has been affected by the attention of the scholars at home and abroad.The content of alpha-damascenone extracted from natural plants is low,and it is far from the market demand because the synthetic route is complex.At present domestic still rely on imports,the price is expensive,and the application is still restricted the compounds.In this paper,three feasible reaction routes were screened out based on the low cost and the same structure of the alpha-damascenone,and the combination of a large number of literatures.Through the bold design and optimization of the route,alpha-damascenone was successfully synthesized.In the synthetic route 1,alpha-damascenone was obtained from alpha-ionone through oximization,iodization and reduction reaction.In the experiment,the reaction path was redesigned,and alpha-damascenone was successfully synthesized by the reaction of epoxidation,oximization,dehydration and reduction reaction.In the reduction reaction,as the reaction system of sodium and ethanol,the purity of each step is better,which greatly reduce the reaction time and steps and saves the cost of operation.In the synthetic route 2,alpha-damascenone was successfully synthesized from alpha-ionone through epoxidation,reduction,halogenation,elimination and oxidation reaction.The bromination and chlorination of hydroxyl groups were carried out in the reaction,and the effect of the halogenation reagents on the elimination reaction was investigated.In the experiment,the key steps were optimized,and the factors such as solvent,reaction time,temperature,catalyst and other factors were investigated,and the optimal reaction conditions were obtained.In the synthetic route 3,alpha-ionone as raw materia went through oxidation reaction of double bond,Wharton rearrangement and oxidation reaction to obtain alpha-damascenone.The route is short and easy to operate,but in the rearrangement reaction of Wharton,a large number of by-products of cyclization are produced.Therefore,the temperature,solvents,alkaline reagents and inhibitors of the system were investigated.The inhibitory effects of the by-products were observed,and the best reaction conditions were screened out.In the experiment,GC-MS,IR,1HNMR and 13 CNMR were used to identify the products in the route.Two dimensional nuclear magnetic resonance(NMR)was usedto characterize the key products in the reaction.Combined with IR data,the spatial structure of these substances was determined,and the structure of the products was correct.