PROCESS FOR RING HALOGENATING ALKYL-SUBSTITUTED AROMATIC ISOCYANATES

摘要

Alkaryl isocyanates are nuclearly halogenated while maintaining reaction conditions (e.g. by effective liquid-gas contacting throughout the reaction zone) so that a reduced proportion of hydrogen halide is present by comparison with known methods. In examples, the alkaryl isocyanate and the halogenating agent are passed countercurrently through a sieve plate tower as reactor. Preferably, the hydrogen halide concentration is kept below 0.6 milliequivalents per g. of (reactants and products). In examples, tolylene diisocyanate is converted to products containing (a) 27.4 or 34.7% nuclear Cl, and (b) 13% nuclear Cl + 29% nuclear Br + 7% alpha-halogen.