GB761594A - Production of isocyanates - Google Patents

Abstract

In a process for the production of organic isocyanates by reacting a salt of a primary amine with phosgene in the presence of an inert diluent, the reactants in the presence of said diluent are passed in a continuous stream through a tube heated to a temperature of at least 50 DEG C. Amine hydrochlorides may be employed as starting materials, e.g. in mixtures with carbamyl chlorides obtained by reacting phosgene with amines or certain amine salts such as carbaminates in the presence of an inert diluent. In the apparatus in the drawing a primary amine salt phosgene and an inert diluent are passed optionally through preheater 1 to the bottom of tower 2 with additional phosgene if desired and the reaction is completed in tower 3 with additional phosgene and the isocyanate is distilled from the reacted mixture leaving the top of tower 3. Vapours <PICT:0761594/IV(b)/1> leaving towers 2 and 3 are condensed in coolers 4 and 5 and returned to the bottoms of the towers. In examples: toluylene diisocyanate is obtained by mixing toluylene diamine, phosgene and o-dichlorobenzene and passing the product through the apparatus described (1); naphthalene 1,5-diisocyanate is similarly prepared from 1,5-naphthalene diamine (2); p-ethoxyphenyl isocyanate is similarly prepared from p-phenetidine using chlorbenzene as solvent (3); octadecane-1-isocyanate is similarly prepared from octadecylamine-1 (4); a -naphthylene isocyanate is similarly obtained from a -naphthylamine (5). The products are worked up by distillation after removal of dissolved phosgene by blowing with nitrogen. Specifications 761,590 and 761,592 are referred to.