An improved process for the preparation of methyl isocyanate comprising reacting methyl carbamoyl chloride with an acid acceptor selected from the group consisting of 1,3-dimethylurea, urea, alkyl ureas and biuret in an organic solvent in which the acid acceptor is soluble but in which the hydrochloride salt thereof is insoluble, separating the acid acceptor hydrochloride from the liquid phase, recovering methyl isocyanate by distillation from the liquid phase, and thermally decomposing acid acceptor hydrochloride to at least a partially free acid acceptor which can preferably be used as a starting material for the production of methyl isocyanate.

This invention relates to an improved process for the preparation of an aliphatic monoisocyanate from the corresponding carbamic acid chloride. The carbamic acid chloride is reacted with an active hydrogen compound. The reaction is conducted in the presence of a solvent which is inert under the reaction conditions. Addition compounds are formed with the elimination of hydrogen chloride. The addition compounds are subsequently decomposed by heat into the desired isocyanate with the mixture also containing the active hydrogen compound. The monoisocyanate is subsequently removed by distillation.

An improved process for converting N-hydroxythioimidates to N-(methylcarbamoyloxy)-thioimidates by reaction with methylcarbamoyl chloride at pH above 10 in a two-phase reaction medium: water and a water-immiscible organic solvent.