S. Aso, T. Baba
Oct 28, 2003
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ChemInform
Abstract
The carbamic acid esters (carbamates) are prepared by alkoxycarbonylation of 2, 4-tolylenediamine with dimethylcarbonate, diethylcarbonate and di-n-butylcarbonate. Carbamates are obained in good yields (_•†90%) using zinc acetate as catalyst. Intermediates in the reactions of carbonates and 2, 4-tolylenediamine to carbamates are 3-amino-4-methyl phenyl carbamates and ureas. Carbamates are pyrolyzed to tolylenediisocyanate and corresponding alcohols. The difference in isocyanate yields among carbamates prepared from dimethylcarbonate, diethylcarbonate and di-n-butylcarbonate is also discussed.