Nuclear hydrogenation of n-aryl carbamates
AssigneeUniroyal, Inc.
InventorsRussell E. Malz, Jr., Harold Greenfield
Life of this patent
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Abstract
N-Alicyclic carbamates, useful in making polyurethanes, are prepared by nuclear hydrogenation of an N-aryl carbamate using a group VIII transition metal catalyst. E.g., dimethyl 4,4'-methylenedicarbanilate is contacted with hydrogen and ruthenium catalyst in 2-propanol medium, at 50.degree. C. for 1.3 hours under a pressure of 500-800 psi, to form dimethyl 4,4'-methylenedicyclohexylcarbamate. Acid activation of catalyst is a feature of the invention.
Claims18
A method of making an N-alicyclic carbamate comprising contacting an N-aryl carbamate with hydrogen in an inert solvent medium in the presence of a metal hydrogenation catalyst selected from the group consisting of rhodium, acid-treated rhodium, ruthenium, palladium, acid-treated palladium, nickel, cobalt and acid-treated platinum catalyst, whereby nuclear hydrogenation of the said N-aryl carbamate takes place to form the said N-alicyclic carbamate, the said N-aryl carbamate being selected from the group consisting of those of the formulas I and II as follows:
- ##STR2## wherein, in formula I:
- n is an integer having a value from 1 to 3;
- R is alkyl having from 1 to 18 carbon atoms, a cycloalkyl group having from 5 to 8 carbon atoms, an aryl group having from 6 to 12 carbon atoms, an aralkyl or alkaryl group having from 7 to 12 carbon atoms;
- R.sup.1 is hydrogen, an alkyl group having from 1 to 8 carbon atoms, a cycloalkyl group having from 5 to 8 carbon atoms, or an aryl group having from 6 to 12 carbon atoms;
- and Ar is an aryl group having a valence of n and having from 6 to 18 carbon atoms, containing up to 4 fused rings;
- and wherein, in formula II:
- a and b are integers having values of 1 or 2;
- R.sup.2 and R.sup.6 are the same or different and have meanings stated for R in formula I;
- R.sup.3 and R.sup.5 are the same or different and have meanings stated for R.sup.1 in formula I;
- R.sup.4 is a single bond, --O--, C.sub.1 -C.sub.8 alkylene, C.sub.5 -C.sub.8 cycloalkylene, C.sub.2 -C.sub.8 alkylidene, or C.sub.2 -C.sub.8 alkenylene;
- and Ar.sup.1 and Ar.sup.2 are the same or different and are divalent or trivalent groups derived from radicals having the meanings assigned to Ar in formula I;
- the said method being carried out at a temperature of 25.degree.-200.degree. C and a pressure of 100 to 2500 psi.
Dependencies are inferred from the claim text.