Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1981-12-16
1983-05-31
Torrence, Dolph H.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
560 24, C07C11800
Patent
active
043860338
ABSTRACT:
A carbamic acid ester corresponding to the formula R.sup.1 --NH--CO--OR.sup.2 is thermally cleaved to form isocyanate R.sup.1 --NCO and alcohol R.sup.2 --OH fractions. This cleavage is accomplished by boiling the carbamic acid ester, condensing the vapor given off in a first fractionation 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.degree. to 260.degree. 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 isocyanate R.sup.3 --NCO is produced. The radicals R.sup.1, R.sup.2, and R.sup.3 are defined herein.
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Heitkamper Peter
Konig Klaus
Bayer Aktiengesellschaft
Gil Joseph C.
Harsh Gene
Torrence Dolph H.
Whalen Lyndanne M.
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