| 摘要 |
1503965 Isocyanate preparation ATLANTIC RICHFIELD CO 23 May 1975 [13 June 1974] 22879/75 Heading C2C Isocyanates are prepared by thermally decomposing a carbamate having the formula R(NHCOOR<SP>1</SP>) x where R is an optionally substituted benzene ring, R<SP>1</SP> is C 1 to C 3 alkyl and x is 1 or 2, the R<SP>1</SP> groups being the same or different when x is 2, at 230-290‹ C. in a continuous process in an inert solvent, higher boiling than the isocyanate, the total concentration of the carbamate and products therefrom being from 1 to 20 mole per cent, in the presence of an inert carrier agent having a b.p. below the isocyanate product, at a mole ratio of inert carrier to carbamate of at least 3 : 1, the isocyanate and corresponding alcohol being recovered as overhead products. |
