Method for the production of (meth)acrylic esters
The present invention relates to a process for preparing (meth)acrylates, comprising the transesterification of a low-boiling ester of (meth)acrylic acid with a reactant alcohol in the presence of catalysts, which is characterized in that the transesterification is catalysed by a basic ion exchanger.
1. A process for preparing a (meth)acrylic ester, the process comprising transesterifying a low-boiling ester of (meth)acrylic acid with a reactant alcohol in a reaction mixture in the presence of a catalyst, wherein the transesterifying is catalyzed by the catalyst, which is a basic ion exchanger, and wherein the transesterifying is effected at a temperature in a range from 70° C. to 120° C., wherein the basic ion exchanger is an anionic crosslinked styrene divinyl benzene copolymer containing quaternary ammonium groups, wherein the basic ions are hydroxide ions;
wherein the reactant alcohol is at least one monohydric or polyhydric alcohol selected from the group consisting of butanol, hexanol, 3 methylbutanol, heptanol, 2-ethylhexyl alcohol, 2 tert butylheptanol, octanol, 3 isopropylheptanol, nonanol, decanol, undecanol, 5 methylundecanol, dodecanol, 2 methyldodecanol, tridecanol, 5 methyltridecanol, tetradecanol, pentadecanol, hexadecanol, 2 methylhexadecanol, heptadecanol, 5 isopropylheptadecanol, 4 tert butyloctadecanol, 5 ethyloctadecanol, 3 isopropyloctadecanol, octadecanol, nonadecanol, eicosanol, cetyleicosanol, stearyleicosanol, docosanol, eicosyltetratriacontanol, ethylene glycol, trimethylolpropane, 1,2-propanediol, 1,3-propanediol, 1,3 butanediol, 1,4-butanediol, ethoxylated bisphenol A, 1,6-hexanediol, and pentaerythritol.
2. The process according to claim 1 , wherein the basic ion exchanger is a strongly basic ion exchanger.
3. The process according to claim 1 , wherein the low-boiling ester is at least one selected from the group consisting of methyl (meth)acrylate and ethyl (meth)acrylate.
4. The process according to claim 1 , further comprising removing an alcohol released from the low-boiling ester of (meth)acrylic acid is by distillation.
5. The process according to claim 1 , wherein the reactant alcohol is a monohydric alcohol.
6. The process according to claim 5 , wherein the reactant alcohol is at least one selected from the group consisting of butanol, hexanol, 3 methylbutanol, heptanol, 2-ethylhexyl alcohol, 2 tert butylheptanol, octanol, 3 isopropylheptanol, nonanol, decanol, undecanol, 5 methylundecanol, dodecanol, 2 methyldodecanol, tridecanol, 5 methyltridecanol, tetradecanol, pentadecanol, hexadecanol, 2 methylhexadecanol, heptadecanol, 5 isopropylheptadecanol, 4 tert butyloctadecanol, 5 ethyloctadecanol, 3 isopropyloctadecanol, octadecanol, nonadecanol, eicosanol, cetyleicosanol, stearyleicosanol, docosanol, and eicosyltetratriacontanol.
7. The process according to claim 1 , wherein the reactant alcohol is a polyhydric alcohol.
8. The process according to claim 7 , wherein the reactant alcohol is at least one selected from the group consisting of ethylene glycol, trimethylolpropane, 1,2-propanediol, 1,3-propanediol, 1,3 butanediol, 1,4-butanediol, ethoxylated bisphenol A, 1,6-hexanediol, and pentaerythritol.
9. The process according to claim 1 , wherein the reaction mixture comprises at most 0.5% by weight of water.
10. The process according to claim 9 , wherein the reaction mixture comprises at most 0.05% by weight of water.
11. The process according to claim 1 , wherein a molar ratio of low-boiling ester of (meth)acrylic acid to reactant alcohol present in the reaction mixture is increased during the transesterifying by at least 40% by adding low-boiling ester of (meth)acrylic acid.
12. The process according to claim 1 , further comprising removing a mixture which comprises methyl methacrylate and methanol.
13. The process according to claim 1 , further comprising adding methyl methacrylate during the transeserifying.
14. The process according to claim 1 , wherein reaction time is in a range from 3 to 20 hours.
15. The process according to claim 1 , wherein the basic ion exchanger comprises at least one selected from the group consisting of hydroxide ions and carbonate ions.
16. The process according to claim 1 , wherein a weight ratio of the reactant alcohol to the low-boiling ester of (meth)acrylic acid is in a range from 2:1 to 1:10.
17. The process according to claim 1 , wherein the transesterifying is effected at a pressure in a range from 200 to 2000 mbar.
18. The process according to claim 1 , wherein the transesterifying is effected in the presence of a polymerization inhibitor.
19. The process according to claim 1 , performed continuously.
20. A process according to claim 1 , wherein a used basic ion exchanger, already employed in a prior transesterifying, is the catalyst.
21. The process according to claim 1 , further comprising regenerating spent basic ion exchanger by treating the spent basic ion exchanger with an aqueous alkali metal hydroxide or carbonate solution.