Method for making carbamates, ureas and isocyanates
View Patent ↗The present invention provides methods of forming carbamates, ureas, and isocyanates. In certain embodiments these methods include the step of reacting an amine with an ester-substituted diaryl carbonate to form an activated carbamate which can be further derivitized to form non-activated carbamate or a urea. The urea or carbamate can be subjected to a pyrolysis reaction to form isocyanate.
1. A method of making a compound of the formula:
X 1 —C(═O)—X 2
wherein X 1 is NR 1 R 2 and X 2 is NR 3 R 4 or OR 5 , and wherein
R 1 , R 2 , and R 3 and R 4 , if present, are each independently selected from the group consisting of hydrogen, optionally-substituted linear or branched alkyl, a heteroatom-containing alkyl, alkene, cycloalkyl, cycloalkenyl, aryl, heteroatom-containing aryl, heteroatom-containing aralkyl, and aralkyl groups, or R 1 and R 2 in combination are a carbon atom double bonded to the nitrogen of X 1 or R 3 and R 4 in combination are a carbon atom double bonded to the nitrogen of X 2 or the N of X 1 or X 2 may be the nitrogen of a ring system, and
R 5 , if present, is selected from the group consisting of optionally-substituted linear or branched alkyl, a heteroatom-containing alkyl, aryl, heteroatom-containing aralkyl, and aralkyl groups, or
R 1 or R 2 in combination with R 3 , R 4 , or R 5 form a five or six-member ring, said method comprising reacting HNR 1 R 2 , and HNR 3 R 4 or HOR 5 with an ester-substituted diaryl carbonate to form the compound.
2. The method of claim 1 , wherein the ester-substituted diaryl carbonate is bismethylsalicylcarbonate (BMSC).
3. The method of claim 1 , wherein X 2 is NR 3 R 4 , whereby the compound formed is a urea.
4. The method of claim 3 , said method comprising reacting at least two moles of one or more primary or secondary amines or one mole diamine with an ester-substituted diaryl carbonate to form the urea.
5. The method of claim 3 , wherein R 1 or R 2 in combination with R 3 or R 4 forms a five or six-member ring.
6. The method of claim 1 , wherein X 2 is OR 5 , whereby the compound formed is a carbamate.
7. The method of claim 6 , said method comprising combining a primary or secondary amine with an ester-substituted diaryl carbonate to form a reaction mixture, and allowing the reactions mixture to react to form the carbamate.
8. The method of claim 7 , where the reaction mixture further comprises an alcohol.
9. The method of claim 6 , wherein R 1 or R 2 in combination with R 5 forms a five or six-member ring.
10. The method of claim 1 , wherein the reaction is performed at a temperature of less than 120° C.
11. The method of claim 10 , wherein the reaction is performed at a temperature of less than 60° C.
12. The method of claim 1 , wherein the reaction is performed for a period of 24 hours or less.
13. The method of claim 12 , wherein the reaction is performed for a period of 4 hours or less.
14. The method of claim 13 , wherein the reaction is performed for a period of 30 minutes to one hour.
15. The method of claim 1 , wherein the reaction is performed in the presence of a catalyst.
16. The method of claim 15 , wherein the catalyst is present in an amount of 0.1 to 1 mole catalyst per mole of ester-substituted diaryl carbonate.
17. The method of claim 1 , wherein the reaction is performed in the absence of any catalyst.
18. A method for forming isocyanates, comprising forming a compound in accordance with claim 1 , and pyrolyzing the compound to form an isocyanate.