Use of high boiling solvents or solvent mixtures as heat exchange medium in the thermal decomposition of carbamic esters

摘要

The use of a solvent (I) for the thermal cracking of carbamic esters (II) is claimed. (I) has a definite b.pt. (pure substance) or a narrow boiling range 10 degrees C at the operating pressure and is obtained as distillation cut of thermostable liquids. Preferably (I) is a distillation cut of commercially-available heat transfer oils, e.g. partly hydrogenated terphenyl, dibenzyltoluene, phenoxybiphenyl and o-phenoxybiphenyl. Its boiling range especially is 3 degrees C at the operating pressure. Cracking is carried out in a reactive rectification column.