| 摘要 |
Diphenylmethane dicarbamates and polymethylene polyphenyl carbamate homologs and derivatives of these compounds are porduced by the condensation of N-aryl carbamic acid esters, such as ethyl phenyl carbamate, with formaldehyde, para-formaldehyde or trioxane in the presence of an organic sulfonic or halogenated organic sulfonic acid which has an acid concentration of at least 75 %, at temperatures of from ambient to about 175≦̸C, and optionally in the presence of an inert solvent.
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