HOMOGENEOUS REACTION OF CARBON DISULFIDE AND o-PHENYLENE DIAMINE IN THE PRESENCE OF POTASSIUM HYDROXIDE

Abstract

ABSTRACT The reaction of carbon disulfide and o-phenylene diamine catalyzed by tertiary amine in the presence of potassium hydroxide is investigated. The role of KOH on the reaction is tested by conducting several independent experiments that included reaction of carbon disulfide and potassium hydroxide for a period, and further reaction of o-phenylene diamine in various sequential orders. Based on experimental data, a kinetic model that take into account the reaction of carbon disulfide and o-phenylene diamine in the presence of KOH catalyzed by tertiary amines is proposed. A reaction mechanism is proposed in which carbon disulfide and tertiary amine first reacted to produce the active intermediate CS2-R3N. This intermediate further reacts with o-phenylene diamine to produce mercaptobenzimidazole (MBI). The reaction is greatly accelerated in the presence of both tertiary amine and potassium hydroxide, but this enhancement in the reaction of carbon disulfide and o-phenylene diamine with tertiary amine exceeded that with potassium hydroxide. An optimum amount of KOH is obtained in the reaction. Satisfactory explanation accounts for the effect of KOH on the conversion.