Process for the preparation of N-alkyl-pyrrolidones
View Patent ↗A process for the production of N-alkylpyrrolidone from γ-butyrolactone and monoalkylamine in the liquid phase comprising the steps of: feeding monoalkylamine and γ-butyrolactone, in the absence of water or in the presence of less than about 1 wt % of water, to a reaction zone to form a reaction mixture; heating the reaction mixture; withdrawing a product stream from the reaction zone and passing the stream to a distillation zone comprising at least one distillation column operated at sub-atmospheric pressure; adding water to the distillation zone; isolating at least one overhead stream from the distillation zone comprising monoalkylamine, water and optionally N-alkyl-pyrrolidone and condensing the overhead stream against cooling water.
1. A process for the production of N-alkyl-pyrrolidone from γ-butyrolactone and monoalkylamine in the liquid phase comprising the steps of:
feeding monoalkylamine and γ-butyrolactone, in the absence of water or in the presence of less than about 1 wt % of water, to a reaction zone to form a reaction mixture;
heating the reaction mixture;
withdrawing a product stream from the reaction zone and passing the stream to a distillation zone comprising at least one distillation column operated at sub-atmospheric pressure;
adding water to the distillation zone;
isolating at least one overhead stream from the distillation zone comprising monoalkylamine, water and optionally N-alkyl-pyrrolidone and condensing the overhead stream against cooling water.
2. A process according to claim 1 wherein the reaction mixture comprises a molar excess of monoalkylamine to γ-butyrolactone.
3. A process according to claim 2 where the molar excess is at least 1.05:1.
4. A process according to claim 1 wherein the water present in the reaction mixture is less than 0.2 wt %.
5. A process according to claim 1 wherein two or three distillation columns are used.
6. A process according to claim 5 wherein each distillation column is operated at sub-atmospheric pressure.
7. A process according to claim 1 wherein the pressure of the at least one distillation column is from about 0.05 bar absolute to about 0.3 bar absolute.
8. A process according to claim 1 wherein the water added to the distillation zone is added directly to the at least one distillation column operated at sub-atmospheric pressure.
9. A process according to claim 1 wherein the temperature of the cooling water is from about 5° C. to about 35° C.
10. A process according to claim 1 wherein the monoalkylamine is monomethylamine and the product is N-methyl-pyrrolidone.