Phosgene → Cyclohexyl isocyanate

Participants

Reaction Steps

500 g of chlorobenzene and 4.3 g of p-toluenesulfonamide (0.025 mol) were placed in the glass vessel and 33 g of gaseous phosgene was introduced at room temperature. The reaction mixture was subsequently heated to 79° C., with vigorous phosgene reflux being established. While stirring vigorously at 78–81° C., a total of 99.2 g of cyclohexylamine (1 mol) dissolved in 200 g of chlorobenzene and at the same time a further 122 g of phosgene were introduced over a period of 3 hours. After addition was complete, the system was maintained at 78–81° 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 fluid suspension from which the solid obtained was separated by filtration. <0.5 g of solid was able to be isolated in this way. Cyclohexyl isocyanate was worked up by distillation. Removal of the solvent and fractional distillation gave 105.1 g of cyclohexyl isocyanate (0.833 mol). This corresponds to 83.3% of the theoretical yield.

Provenance & Evidence