Preparation of substituted 2-fluoroacrylic acid derivatives

A process for the preparation of compounds of the formula (I),

• wherein R1 and R2 are identical or different and are, independently of one another, hydrogen, C1-C15-alkyl, (C6-C24-aryl or C1-C15-alkoxy, and R3 is C1-C15alkoxy, the process comprising:
• reacting compounds of the formula (II),
• wherein R1, R2 and R3 have the abovementioned meanings, and X is Cl, Br, I or a pseudohalogen, in the presence of:
• at least one base,
• a high-boiling-point polar aprotic solvent selected from the group consisting of ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethylether, dimethylformamide, dimethyl sulfoxide, sulfolane, ortho-dichlorobenzene, N-methylpyrrolidone, and mixtures thereof, and
• at least one polymerization inhibitor selected from the group of 2,2,6,6-tetramethylpiperidine N-oxyl, sulfur, p-benzoquinone, 4-tert-butylcatechol, phenothiazine, di-tert-butylhydroxytoluene (BHT) and mixtures thereof.