SELECTIVE METHOD OF 4,4-METHYLENE-BIS-(N-PHENYL ALKYL CARBAMATE)

摘要

This relates to a manufacturing method of 4,4-methylene-bis(N-phenylalkylcarbamate) of (I). The preparing method comprises : 1)condensation of N-phenylalkylcarbamate with methylating agent in the acidic solution and non-hydrogen bonded hydrogen containing solvent; 2)forming emulsion type product; and 3)filtering and separating the product at above the melting point of N-phenylalkylcarbamate. 4,4-Methylene-bis(N-phenylalkylcarbamate) is a precursor of the pure MDI.