Synthesis Of 2,2-dibenzyl-substituted Malononitrile Derivatives

Malononitrile derivatives have a wide range of biological activities,which are widely used in the field of pharmaceuticals,pesticides,dyes,etc.Especially,in the field of pesticide,insecticide,sterilization and weeding,biological activity has always been a research hotspot.By designing the molecular structure,the two hydrogen atoms in a-position of the cyano group of malononitrile can be mono-substituted or di-substituted,the different structures of substituents allow the derivative compounds possessing unique biological activities.In this dissertation,a-position of cyano of malononitrile was di-substituted by benzylic groups to get 2,2-dibenzyl-substituted malononitrile,which could be alcoholyzed to their ester compounds.Firstly,the methyl group of toluenes were halogenated using boron trihalides as the halogenation reagents to obtain five benzyl halogen derivatives:4-nitrobenzyl chloride,4-chlorobenzyl chloride,4-cyanobenzyl chloride,4-bromobenzyl bromide and 4-fluorobenzyl bromide.Next,two strong alkaline ionic liquid accelerator,ethanol solution of hydroxide N-(4-bromobenzyl)pyridine and ethanol solution of hydroxide N-(4-cyanobenzyl)pyridine,were synthesized.Finally,five 2,2-dibenzyl-substituted malononitrile derivatives 2,2-dibenzyl malononitrile,2,2-bis(4-cyanobenzyl)malononitrile,2,2-bis(4-chlo robenzyl)malononitrile,2,2-bis(4-fluorobenzyl)malononitrile and 2,2-bis(4-bro minebenzyl)malononitrile,were synthesized from malononitrile and benzyl halogen derivatives under basic conditions.2,2-Dibenzyl-substituted malononitri les were futher alcoholyzied to get three ester compounds,2-cyano-2,2-bis(4-fluo robenzyl)ethyl acetate,2-cyano-2,2-bis(4-bromidebenzyl)ethyl acetate and 2-cyano-2,2-bis(4-chloridebenzyl)ethyl acetate.IR spectrum,HNMR spectrum and X-ray diffraction were used to analysis and determine the molecular structure.Benzyl halogen derivatives,ionic liquid accelerator and ester compounds were synthesized according to literature.All synthesis methods and experimental conditions were simplified and optimized.The influence of different factors on the synthesis of 2,2-dibenzyl-substituted malononitrile derivatives,such as kind of alkaline accelerator,reaction temperature,reaction time and ratio of raw materials,have been studied.It was found that the optimal reaction conditions were:malononitrile and alkaline accelerator molar ratio of 1:2.2,malononitrile and benzyl halogen derivatives molar ratio of 1:2,at room temperature with sodium ethoxide as a alkaline accelerator.