Study On The Synthesis Of O-mercaptobenzonitrile

o-mercaptobenzonitrile is an important industrial raw material and pharmaceutical intermediate which can be used to prepare nematic liquid-crystalline products, herbieides, Pharmaceuticals and dyes et al. The reported inventions relating to the process for the preparation of o-mercaptobenzonitrile have problems about shortage of raw materials, harsh reaction conditions, and low yields. There is thus a need for a process with which o-mercap-tobenzonitrile can be prepared in a simple manner and with good yields.A process for the preparation of p-mercaptobenzonitril was used for reference, and then a process for the preparation of o-mercaptobenzonitril from o-halogenobenzonitrile is drafted. o-mercaptobenzonitrile is prepared by reacting the appropriate o-chlorobenzonitrile with anhydrous sodium sulfide in the presence of an inert organic solvent N,N-dimethylformamide (DMF), and subsequently acidifying, of which the structure has been characterized through 1H-NMR and MS techniques. The effects of reaction time, temperature, feed ratio, the volume of solvent and pH on the reaction were investigated. Under the optimum conditions(T=90℃, t=3h, o-chlorobenzonitrile/sodium sulfide=1:1.1 (molar ratio), DMF=55 mL, pH=2), o-Mercaptobenzonitrile yield of 73% was attained.