In situ process for preparing quaternary ammonium bicarbonates and quaternary ammonium carbonates
View Patent ↗Applicant has discovered an in situ method of preparing quaternary ammonium methocarbonate salts and quaternary ammonium alkylcarbonate salts in high yield from tertiary amines, methanol, and at least one of a cyclic carbonate, an aliphatic polyester (such as a polycarbonate), or an ester (such as a carbonate ester), and their subsequent conversion to quaternary ammonium bicarbonates, quaternary ammonium carbonates or both in a one-pot reaction. According to one embodiment of the invention, the method includes reacting an amine and methanol with at least one of a cyclic carbonate and an aliphatic polyester to yield a quaternary ammonium methocarbonate. This method does not produce or require the handling of corrosive quaternary ammonium hydroxides. Another embodiment is a method of preparing quaternary ammonium alkylcarbonate salts by reacting tertiary amines, methanol, and an ester. The quaternary ammonium methocarbonate or alkylcarbonate can be converted to the corresponding bicarbonate, carbonate, or mixture thereof by methods known in the art.
1. A method of preparing a quaternary ammonium alkylcarbonate having the formula
wherein R 1 and R 2 are independently C 1 -C 30 alkyl, R 3 is a C 8 -C 30 alkyl, and R 9 is a C 1 -C 10 alkyl, the method comprising reacting
(a) an amine having the formula NR 1 R 2 R 3 ;
(b) an ester having the formula
wherein R 10 is a C 1 -C 10 alkyl; and
(c) methanol
to form the quaternary ammonium alkylcarbonate.
2. The method of claim 1 , wherein R 1 is methyl and R 2 and R 3 are independently C 8 -C 12 alkyl.
3. The method of claim 1 , wherein the amine is selected from the group consisting of didecylmethylamine, dodecyldimethylamine, dioctylmethylamine, octadecyldimethylamine, dioctadecylmethylamine, trioctylamine, and any combination of any of the foregoing.
4. The method of claim 1 , wherein the molar ratio of amine to ester ranges from about 1:1 to about 1:10.
5. The method of claim 4 , wherein the molar ratio of amine to ester ranges from about 1:2 to about 1:3.
6. The method of claim 1 , wherein the molar ratio of amine to methanol ranges from about 1:2 to about 1:20.
7. The method of claim 1 , wherein the reaction step is performed at from about 120 to about 160° C.
8. The method of claim 7 , wherein the reaction step is performed at from about 120 to about 150° C.
9. The method of claim 8 , wherein the reaction step is performed at from about 120 to about 140° C.
10. The method of claim 1 , further comprising the step of recovering alkanol having the formula R 9 OH.
11. The method of claim 1 , wherein the reaction step comprises reacting
(a) the amine;
(b) the ester;
(c) methanol; and
(d) alkyl methyl carbonate having the formula CH 3 OC(O)OR 9 .
12. A method of preparing a quaternary ammonium bicarbonate having the formula
wherein R 1 , R 2 , and R 3 are independently C 1 -C 30 alkyl, the method comprising
(a) preparing a quaternary ammonium alkylcarbonate by the method of claim 1 ; and
(b) converting the quaternary ammonium alkylcarbonate to the quaternary ammonium bicarbonate.