Process for the manufacture of alkylfluoroacrylate
The invention relates to a process for the manufacture of an alkylfluoroacrylate starting from alkylfluoroacetate and an oxalic acid ester, wherein an alkane liquid under the reaction conditions is applied as the solvent in one of the reaction steps.
1. A process for the manufacture of a methylfluoroacrylate, comprising the following steps:
A. a methylfluoroacetate with an ester of oxalic acid is reacted in the presence of a base and a suitable solvent in a crossed Claisen condensation reaction resulting in a Claisen salt;
B. the Claisen salt obtained in step A is optionally filtered off and washed with a suitable solvent;
C. the Claisen salt obtained in step A or B is reacted with paraformaldehyde in a suitable solvent;
D. the methylfluoroacrylate obtained in step C is isolated using a suitable solvent, wherein the methylfluoroacrylate isolated after distillation has a purity of at least 99.5 wt %, contains below 0.5 wt % methylfluoroacetate and below 2.0 wt % dimethyl carbonate;
wherein the solvent in at least steps C and D and optionally in one of steps A or B is an alkane selected from a group consisting of pentane and hexane.
2. The process according to claim 1 , wherein the alkane is pentane.
3. The process according to claim 1 or 2 , wherein the solvent in steps C and D comprises the alkane.
4. The process according to claim 1 , wherein the ester of oxalic acid is dimethyloxalate.
5. The process according to claim 1 , wherein the base in the Claisen condensation reaction is a metal alkoxide represented by the formula MOR, wherein M is sodium or potassium and R is a C 1 -C 4 alkyl group.
6. The process according to claim 1 , wherein the base in the Claisen condensation reaction is a metal alkoxide of the formula MOR in a C 1 -C 4 alcohol.
7. The process according to claim 1 , wherein the base is sodium methoxide in methanol.
8. The process according to claim 1 , wherein the solvent in step A is methyl-tert-butylether or pentane.
9. The process according to claim 1 , wherein methylfluoroacrylate obtained after the reaction with paraformaldehyde is quenched with water before isolation.
10. The process according to claim 1 , wherein the isolation comprises a filtration and a distillation.