| 摘要 |
PURPOSE:To obtain industrially and advantageously the titled compounds useful for preparing isocyanates in high yield without using phosgene, by reacting methyl N-phenylcarbamate with HCHO, etc. under specific conditions, and separating deposited substances. CONSTITUTION:Methyl N-phenylcarbamate is reacted with HCHO or a substance capable of generating HCHO, e.g. paraformaldehyde or trioxane, in the presence of an acid catalyst, e.g. HCl or H2SO4, in a solvent containing water in a heterogeneous state, and diphyenylmethane dimethyl carbamate to be deposited is separated. The residual reactants are reacted in the presence of the acid catalyst in substantially the homogeneous state to separate and obtain the diphenylmethane dimethyl carbamate and polymethylene polyphenylpolymethyl carbamate. The above-mentioned method has advantages as follows; The selectivity of the aimed substances is improved without reducing the rate of reaction of the raw materials. Small-sized reactors are sufficiently used.
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