C - Chemistry – Metallurgy – 07 – C
Patent
C - Chemistry, Metallurgy
07
C
260/455, 260/637
C07C 31/02 (2006.01) B01J 23/06 (2006.01) B01J 27/08 (2006.01) B01J 31/02 (2006.01) B01J 31/04 (2006.01) B01J 31/12 (2006.01) C07B 61/00 (2006.01) C07C 29/00 (2006.01) C07C 31/13 (2006.01) C07C 33/18 (2006.01) C07C 35/02 (2006.01) C07C 37/00 (2006.01) C07C 263/04 (2006.01) C07C 265/04 (2006.01) C07C 265/10 (2006.01) C07C 265/12 (2006.01)
Patent
CA 1178291
ABSTRACT OF THE DISCLOSURE A carbamic acid ester corresponding to the formula R1-NH-CO-OR2 is thermally cleaved to form iso- cyanate R1-NCO and alcohol R2-OH fractions. This cleavage is accomplished by boiling the carbamic acid ester, condensing the vapor given off in a first frac- tionation column, and condensing the vapor from the first fractionation column in a second fractionation column. The boiling of the carbamic acid ester is carried out in a manner such that the average dwell time in the reaction vessel is from 1 to 20 hours, the temperature is from 160 to 260°C and the pressure is from 0.001 to 2 bar. The isocyanate fraction obtained by this cleavage process may be used as a starting material for a transurethanation reaction in which a lower boiling isocyante R3-NCO is pro- duced. The radicals R1, R2, and R3 are defined herein.
391376
Heitkamper Peter
K"onig Klaus
Aktiengesellschaft Bayer
Norton Rose Or S.e.n.c.r.l. S.r.l./llp
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