Phosgene → Cyclohexyl isocyanate

Participants

Reaction Steps

500 g of chlorobenzene were placed in the glass vessel and 40 g of gaseous phosgene was introduced at room temperature. The reaction mixture was subsequently heated to 77° C., with vigorous phosgene reflux being established. While stirring vigorously at 77–80° C., a total of 99.2 g of cyclohexylamine (1 mol) dissolved in 200 g of chlorobenzene and at the same time a further 92 g of phosgene were introduced over a period of 3 hours. After addition was complete, the system was maintained at 77–80° C. for a further one hour without introduction of phosgene to allow further reaction to occur and the residual unreacted phosgene was subsequently stripped out at 50° C. by means of nitrogen. The reaction mixture obtained was a suspension from which the solid obtained was separated by filtration. 15 g of solid which, according to IR-spectroscopic analysis, was mainly amine hydrochloride were able to be isolated in this way. The filtered crude product was worked up by distillation. Removal of the solvent and fractional distillation gave 88.8 g of cyclohexyl isocyanate (0.710 mol). This corresponds to 71.0% of the theoretical yield.

Provenance & Evidence