Method for producing lactamates by way of thin film evaporation
A method is described for producing lactamates by reacting alcoholates with lactams, wherein a reaction mixture comprising at least one alcoholate and at least one lactam is subjected to thin film evaporation.
1. A process for preparing a lactamate, comprising:
(a) forming a reaction mixture comprising at least one alkoxide and at least one lactam by introducing the at least one lactam to the at least one alkoxide to obtain a reactant mixture wherein said lactam is ε-caprolactam;
(b) homogenizing the reactant mixture at a temperature between 30° and 70° C. to obtain a homogenized reactant mixture wherein the homogenization results in essentially no reaction between the at least one alkoxide with the at least one lactam;
(c) feeding the homogenized reactant mixture into a thin-film evaporator;
(d) reactively distilling the reactant mixture fed in the thin-film evaporator at a temperature of 30 to 60° C., optionally with simultaneous stripping of the reactant mixture in countercurrent; and
(e) obtaining the lactamate in the thin-film evaporator.
2. The process as claimed in claim 1 , wherein the process is performed continuously.
3. The process as claimed in claim 1 , wherein the reactive distillation is performed in a falling-film evaporator.
4. The process as claimed in claim 1 , wherein the alkoxide is an alkali metal alkoxide, alkaline earth metal alkoxide or tetraalkylammonium alkoxide.
5. The process as claimed in claim 1 , wherein the weight ratio of the lactam to the alkoxide in the reaction mixture is 1:1 to 40:1.
6. The process as claimed in claim 1 , further comprising:
subjecting the reaction mixture to a stripping operation during the reactive distillation.
7. The process as claimed in claim 6 , wherein the stripping operation is effected in countercurrent to the flow of the reaction mixture.
8. The process as claimed in claim 1 , further comprising:
finishing the lactamate obtained on a drum flaker or a pelletizing belt.
9. The process as claimed in claim 1 , wherein the process is performed under inert conditions.
10. The process according to claim 1 , wherein the thin-film evaporator further comprises a jacket having an operating temperature from 80 to 180° C.
11. The process according to claim 1 , wherein the thin-film evaporator further comprises a condenser having a temperature from −10° C. to 30° C.
12. The process according to claim 1 , wherein the thin-film evaporator has a pressure of 50 to 900 mbar.
13. The process according to claim 1 , wherein the reactive distillation is via a trickle column.