Process for the preparation of .alpha.-fluoroacryloyl derivatives

A process for the preparation of a .alpha.-fluoroacryloyl derivatives, in which

• a) a dihalogenopropene of the formula (I)
• CH.sub.2 .dbd.CHal.sup.1 --CH.sub.2 Hal.sup.2 (I),
• in which
• Hal.sup.1 and Hal.sup.2, independently of one another, represent chlorine or bromine,
• is reacted with an anhydrous mixture of nitric acid and hydrofluoric acid to give a 1-nitro-2,2-fluorohalogeno-3-halogenopropane of the formula (II)
• CH.sub.2 Hal.sup.2 --CFHal.sup.1 --CH.sub.2 NO.sub.2 (II),
• in which
• Hal.sup.1 and Hal.sup.2 have the meaning given in formula (I),
• b) converting this in the presence of a strong acid selected from the group consisting of sulphuric acid, phosphoric acid, nitric acid, hydrochloric acid, and hydrobromic acid, and 0.9 to 20 mol of water per mol of compound of the formula (II) at elevated temperature in the range of from 50.degree. to 200.degree. C. to a 2,2-fluorohalogeno-3-halogenopropanic acid of the formula
• CH.sub.2 Hal.sup.2 --CFHal.sup.1 --COOH (III),
• in which
• Hal.sup.1 and Hal.sup.2 have the meaning given in formula (I),
• c) converting this into a derivative of the formula (IV)
• CH.sub.2 Hal.sup.2 --CFHal.sup.1 --CO --R (IV),
• in which
• Hal.sup.1 and Hal.sup.2 have the meaning given in formula (I) and
• R represents OR.sup.1 where R.sup.1 =optionally substituted, straight chain, branched or cyclic C.sub.1 -C.sub.18 -alkyl, optionally substituted C.sub.6 -C.sub.14 -aryl or c.sub.6 -C.sub.14 -heteroaryl or represents NR.sup.2 R.sup.3 where R.sup.2 and R.sup.3, independently of one another, represent optionally substituted, straight chain, branched or cyclic C.sub.1 -C.sub.18 -alkyl or where R.sup.2 and R.sup.3 form a 5- to 7-membered ring together with the nitrogen atom which is located between them
• and
• d) this is reacted with a dehalogenating agent to give an .alpha.-fluoroacryloyl derivative of the formula (V)
• CH.sub.2 .dbd.CF --CO--R (V),
• in which
• R has the meaning given in formula (IV).