Process for methyl isocyanate production
OwnerPlacido M. Spaziante, Luigi Giuffreinventors
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Abstract
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.
Claims18
A process for the preparation of methyl isocyanate comprising reacting methylcarbamoyl chloride with about a stoichiometric amount of an acid acceptor selected from the group consisting of dimethylurea, urea, alkyl ureas and biuret in an organic solvent in which said acid acceptor is soluble and in which the hydrochloride salt of said acid acceptor is insoluble, separating the acid acceptor hydrochloride from the liquid phase, recovering methyl isocyanate by distillation from said liquid phase, and thermally decomposing said acid acceptor hydrochloride salt to regenerate said acid acceptor.
A continuous process for the preparation of methyl isocyanate comprising reacting methylcarbamoyl chloride with 1,3-dimethylurea in an organic solvent in which the 1,3-dimethylurea is soluble and in which the 1,3-dimethyl hydrochloride is insoluble, separating the 1,3-dimethyl hydrochloride from the liquid phase, recovering methyl isocyanate by distillation from the liquid phase, subjecting a slurry of 1,3-dimethylurea hydrochloride and the organic solvent to thermal decomposition whereby hydrogen chloride gas is removed leaving a mixture of 1,3-dimethylurea and 1,3-dimethylurea hydrochloride and recycling said latter mixture to the first step for reaction with methylcarbamoyl chloride.
A process for thermal decomposition of 1,3-dimethylurea hydrochloride comprising heating at 80.degree. to 95.degree. C. a solution of 1,3-dimethylurea hydrochloride in an organic solvent under reduced pressure while removing hydrogen chloride gas.
A process for the preparation of methyl isocyanate comprising reacting methylcarbamoyl chloride with at least a stoichiometric amount of 1,3-dimethylurea in an organic solvent in which 1,3-dimethylurea hydrochloride is insoluble, separating the 1,3-dimethylurea hydrochloride from the liquid phase and recovering methyl isocyanate by distillation from the liquid phase.
Dependencies are inferred from the claim text.