Method for synthesizing allyl methacrylate
View Patent ↗The present invention relates to a process for preparing allyl methacrylate, comprising the reaction of allyl alcohol with an ester of methacrylic acid, wherein the reaction is catalyzed by zirconium acetylacetonate. The process according to the invention enables particularly favorable preparation of allyl methacrylate with a very high purity.
1. A process for preparing allyl methacrylate, comprising the reaction of allyl alcohol with an ester of methacrylic acid, wherein the reaction is catalyzed by zirconium acetylacetonate.
2. The process according to claim 1 , wherein methyl methacrylate is used as the ester of methacrylic acid.
3. The process according to claim 1 , wherein the allyl methacrylate comprises less than 0.02 wt. % of allyl alcohol.
4. The process according to claim 1 , wherein the weight ratio of allyl alcohol to the ester of methacrylic acid is in the range of 1:2.5 to 1:5.
5. The process according to claim 4 , wherein the weight ratio of allyl alcohol to the ester of methacrylic acid is in the range of 1:3.0 to 1:4.0.
6. The process according to claim 1 , wherein 0.5 to 2 mmol of zirconium acetylacetonate are used per mole of allyl alcohol.
7. The process according to claim 1 , wherein the reaction is effected at a pressure in the range of 500 to 1300 mbar.
8. The process according to claim 1 , wherein the reaction is effected at a temperature in the range of 80° C. to 120° C.
9. The process according to claim 1 , wherein the temperature at which the reaction is effected is increased in the course of the reaction.
10. The process according to claim 8 , wherein the temperature at the start of the reaction is in the range of 90° C. to 100° C. and is in the range of 105° C. to 115° C. towards the end of the reaction.
11. The process according to claim 1 , wherein the reaction is effected in the presence of a polymerization inhibitor.
12. The process according to claim 11 , wherein the polymerization inhibitor does not contain nitrogen.
13. The process according to claim 11 , wherein a phenol is used as the polymerization inhibitor.
14. The process according to claim 11 , wherein the polymerization inhibitor used is a mixture which comprises hydroquinone and hydroquinone monomethyl ether.
15. The process according to claim 1 , wherein the allyl methacrylate comprises at most 0.02 wt. % water.
16. The process according to claim 1 , wherein the reaction takes place with stirring.
17. The process according to claim 16 , wherein the stirrer speed is in the range of 100 to 500 rpm.
18. The process according to claim 1 , wherein the reaction is effected with introduction of atmospheric oxygen.
19. The process according to claim 18 , wherein 0.05 to 0.51 of air per hour and mole of allyl alcohol is introduced.
20. The process according to claim 1 , wherein the reaction is effected at a pH in the range of 6 to 8.
21. The process according to claim 1 , wherein the alcohol released from the ester of methacrylic acid used is removed by distillation.
22. The process according to claim 21 , wherein ethanol or methanol is removed.
23. The process according to claim 21 , wherein a mixture which comprises methyl methacrylate and methanol is removed.
24. The process according to claim 23 , wherein a portion of the mixture removed is introduced into the next batch.
25. The process according to claim 24 , wherein the recyclable portion of the mixture removed is obtained towards the end of the reaction.
26. The process according to claim 1 , wherein the allyl methacrylate comprises less than 0.01 wt. % of allyl alcohol.