Phosgene → Cyclohexyl isocyanate

Participants

Reaction Steps

500 g of chlorobenzene and 2.4 g of dimethyl sulfone (0.025 mol) were placed in the glass vessel and 30 g of gaseous phosgene was introduced at room temperature. The reaction mixture was subsequently heated to 78° C., with vigorous phosgene reflux being established. While stirring vigorously at 78–80° C., a total of 99.2 g of cyclohexylamine (1 mol) dissolved in 200 g of chlorobenzene and at the same time a further 105 g of phosgene were introduced over a period of 3 hours. After addition was complete, the system was maintained at 78–80° 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. 7.8 g of solid 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 86.8 g of cyclohexyl isocyanate (0.694 mol). This corresponds to 69.4% of the theoretical yield.

Provenance & Evidence