Phenol → Phenyl isocyanate

Participants

Reaction Steps

Diphenyl carbonate (33.2 grams, 0.155 mole) is charged to a 50 ml three-neck flask equipped with a magnetic stirbar, a six inch Vigreaux column topped with a short path distillation head and an electrically heated addition funnel charged with a solution of formanilide (4.69 grams, 0.039 mole) in molten phenol (16.56 grams, 0.176 mole). The diphenyl carbonate is heated to 213° C. at 100 mmHg vacuum and the phenol/formanilide mixture added dropwise over a 50 minute period. When the addition is complete, the vacuum is slowly lowered to 5 mmHg over the next 10 minutes to remove the remaining phenol and phenyl isocyanate from the remaining diphenyl carbonate. Internal standard gas chromatographic (IS/GC) analysis of the overhead (29.72 grams) and pot material (22.94 grams) shows production of 4.17 grams of phenyl isocyanate and 0.02 grams of phenyl isocyanate as phenol carbamate, as a solution in phenyl formate and phenol, a recovery of 0.0352 moles of phenyl isocyanate (91.0% yield, based on formanilide fed). In calculating the yield of isocyanate, the easily thermolyzed carbamate is considered as isocyanate.

Provenance & Evidence