KINETICS AND MECHANISM OF THE THERMAL DECOMPOSITION OF METHYL ISOCYANATE

The kinetics of gas-phase decomposition of methyl isocyanate have been investigated in the range of 427–548°C. Two decomposition routes are followed; the predominant one is a radical-chain process giving CO, H2, and HCN as major products, which has an order of 1.5 and an Arrhenius equation given by log k(L1/2/mol1/2·s) = (13.12 ± 0.06) − (56,450 ± 1670) cal/mol/2.303 RT. The minor route is the bimolecular formation of N,N′-dimethylcarbodiimide and CO2, which from the low activation parameters Ea = 31.6 kcal, A = 105.30 L1/2/mol1/2·s, and the reaction order of 1.57 appears to be heterogeneous.