Method for producing 2-halogen-acrylic acid esters
The present invention relates to a process for preparing 2-haloacrylic esters from 2-hydroxymethyl- or 2-halomethyl- or 2-chlorosulfinyloxymethyl-2-halomalonic diesters. The invention further provides novel 2-halomethyl-2-halomalonic diesters or 2-chlorosulfinyloxymethyl-2-halomalonic diesters which can be used for preparation of the 2-haloacrylic esters.
1. A process for preparing 2-haloacrylic esters of the formula (IV)
in which
R 1 is C 1 -C 15 -alkyl, or C 3 -C 6 -cycloalkyl or C 6 -C 24 -aryl and
X 1 is fluorine, chlorine, chlorosulfinyloxy or bromine,
the process comprising reacting compounds of the formula (II)
and/or compounds of the formula (III)
in each of which R 1 and X 1 have the definition given for formula (IV) and the two R 1 radicals are identical or different, and
where X 2 in formula (III) is fluorine, chlorine or bromine,
in the presence of base to give compounds of the formula (IV).
2. The process according to claim 1 , wherein
R 1 is C 1 -C 6 -alkyl, or C 3 -C 6 -cycloalkyl or C 6 -C 24 -aryl, and
X 1 is fluorine, chlorine or bromine.
3. The process as claimed in claim 1 , wherein:
R 1 in the formulae (I) to (IV) is C 1 -C 6 -alkyl, C 3 -C 6 -cycloalkyl or C 6 -C 24 -aryl, and
X 1 in the formulae (I) to (IV) is fluorine, chlorine or bromine.
4. The process as claimed in claim 1 , wherein X 2 in the formulae (I) to (IV) is chlorine or bromine.
5. The process as claimed in claim 1 , wherein X 2 in the formula (III) is chlorosulfinyloxy.
6. The process as claimed in claim 1 , wherein the compounds of the formula (II) are prepared by hydroxymethylation of dialkyl 2-halomalonates of the formula (I) with formaldehyde
in which R 1 and X 1 have the definitions given in claim 1 .
7. The process as claimed in claim 1 , wherein the compounds of the formula (III) are prepared by reaction of compounds of the formula (II) with a halogenating agent.
8. The process as claimed in claim 7 , wherein the halogenating agents are selected from the group consisting of thionyl chloride, thionyl bromide, phosphorus trichloride, phosphorus tribromide, sulfuryl chloride, sulfuryl bromide and hydrogen halides.
9. The process as claimed in claim 1 , wherein the 2-haloacrylic esters of the formula (IV) are methyl 2-fluoroacrylate or ethyl 2-fluoroacrylate and the compounds of the formula (II) and (III) respectively are:
dimethyl 2-fluoro-2-hydroxymethylmalonate or diethyl 2-fluoro-2-hydroxymethylmalonate, and
dimethyl 2-fluoro-2-chloromethylmalonate or diethyl 2-fluoro-2-chloromethylmalonate.
10. The process as claimed in claim 1 , wherein the 2-haloacrylic esters of the formula (IV) are methyl 2-fluoroacrylate or ethyl 2-fluoroacrylate prepared from compounds of the formula (III) wherein the compounds of the formula (III) are:
dimethyl 2-fluoro-2-chlorosulfinyloxymethylmalonate or diethyl 2-fluoro-2-chlorosulfinyloxymethylmalonate.
11. The process as claimed in claim 1 , wherein the base is selected from organic or inorganic bases.
12. The process as claimed in claim 1 , wherein the base is selected from the group consisting of alkaline earth metal or alkali metal hydroxides, amides, alkoxides, carbonates, hydrogenphosphates, phosphates, for example sodium amide, lithium diethylamide, sodium methoxide, potassium tert-butoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, trisodium phosphate, tripotassium phosphate, disodium hydrogenphosphate, dipotassium hydrogenphosphate, sodium dihydrogenphosphate, potassium dihydrogenphosphate.
13. The process as claimed in claim 1 , wherein the reacting is conducted in the presence of solvent.
14. The process as claimed in claim 1 , wherein the reacting is conducted at a temperature of 120 to 170° C.