Method for preparing cinnamonitriles

Abstract

The invention discloses a method for preparing cinnamonitriles. Firstly the anhydrous sodium carbonate, hydroxylamine hydrochloride and water are mixed to prepare the water solution of hydroxylaminehydrochloride and sodium carbonate, then the water solution of hydroxylamine hydrochloride and sodium carbonate is added drop by drop into the solution of cinnamaldehyde and ethanol or methanol; the obtained solution is fully stirred and rests and ,subsequently the reaction mixture is poured into the ice water till the white precipitation is precipated; the white precipitation is obtained by filtration and washed by water so as to obtain the cinnamonitrile after being dried. 2 to 2..5 times (mol ratio) of acetic anhydride is added drop by drop into the cinnamonitrile, the obtained mixtures arestirred and cooled after going through a dehydration reaction, and then the obtained mixtures are subject to a vacuum distillation so as to recycle the acetic anhydride and the acetic acid producedby reaction. A further vacuum depression distillation is carried out to collect the stable fraction under a pressure ranging from 130 to 132 DEG C / 2064Pa or 151.0 DEG C / 5,330Pa, and obtain the cinnamonitriles. The method has simple operation, needs cheap raw materials, causes no contamination and has high yield.

Description

technical field [0001] The invention relates to a preparation method of cinnamonitrile, which belongs to the field of chemistry. Background technique [0002] Cinnamonitrile is an excellent synthetic fragrance, which is widely used in daily chemicals and soap fragrances. Its traditional synthetic method is: prepare cinnamon aldoxime in methanol, then use phosphorus oxychloride (POCl 3 ) to dehydrate cinnamon aldoxime to generate cinnamonitrile. The disadvantage of this method is that the reaction time is long and the operation is complicated, especially POCl 3 , is easily hydrolyzed, and uses toxic solvents such as benzene and methanol; under microwave conditions, SiO 2 / K 2 CO 3 Facilitated solvent-free method from cinnamaldehyde / NH 2 OH·HCI is a method for directly preparing cinnamonitrile, but this method is still in the theoretical stage, and microwave radiation is used, the heating is uneven, the failure rate is high, the reliability is poor, it is difficult to ope...

AI Technical Summary

Problems solved by technology

Its traditional synthetic method is: prepare cinnamon aldoxime in methanol, then use phosphorus oxychloride (POCl 3 ) to dehydrate cinnamon aldoxime to generate cinnamonitrile. The disadvantage of this method is that the reaction time is long and the operation is complicated, especially POCl 3 , is easily hydrolyzed, and uses toxic solvents such as benzene and methanol; under microwave conditions, SiO 2 / K 2 CO 3 Facilitated solvent-free method from cinnamaldehyde / NH 2 OH·HCI is a method for directly preparing cinnamonitrile, but this method is still in the theoretical stage, and microwave radiation is used, the heating is uneven, the failure rate is high, the reliability is poor, it is difficult to operate and maintain, and the cost is expensive, so it needs to be applied to production. Cinnamonitrile is synthesized by base phase transfer catalytic dehydration method, which is synthesized by KOH-TBAB catalytic dehydration method. Not only the conversion rate of cinnamon aldoxime dehydration into cinnamonitrile is high, but also the consumption of KOH and TBAB is small, and the solvent toluene can also be used repeatedly. Synthetic The cost is low, but this method is difficult to control some conditions and factors in the preparation process, which will easily lead to the intensification of side reactions and reduce the yield, and the washing and purification process is complicated, which is not suitable for industrial large-scale production;