Phosgene → Cyclohexyl isocyanate

Participants

Reaction Conditions

Reaction Steps

500 g of chlorobenzene and 8.7 g of Cyanex® 923 (commercial product from Cytec Industries, a mixture of different tri-C6-C8-alkylphosphine oxides having an average molecular weight of 348 g/mol) (0.025 mol) were placed in the glass vessel and 53 g of gaseous phosgene was introduced at room temperature. The reaction mixture was subsequently heated to 80° 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 113 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 40° C. by means of nitrogen. The reaction mixture obtained was a fluid suspension from which the solid obtained was separated by filtration. A few milligrams 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 82.8 g of cyclohexyl isocyanate (0.662 mol). This corresponds to 66.2% of the theoretical yield.

Provenance & Evidence