Patent ID: 7714144

Claim:
Process for preparing 5-fluoro-1,3-dialkyl-1H-pyrazole-4-carbonyl fluorides of the formula (I) in which R 1 and R 2 are each independently C 1 -C 3 -alkyl, comprising: converting 5-chloro-1,3-dialkyl-1H-pyrazole-4-carbonyl chlorides of the formula (II) in which R 1 and R 2 are each as defined above in the presence of potassium fluoride, in the presence of a phase transfer catalyst selected from (A) a quaternary phosphonium compound of the formula (III) in which R 3 , R 4 , R 5 and R 6 are each independently C 1 -C 22 -alkyl, in each case optionally substituted aryl or (C 1 -C 4 -alkyl)aryl, where aryl is defined as phenyl or naphthyl, and the said substituents are halogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, nitro or cyano, X − is an anion, or (B) an amidophosphonium salt of the formula (IV) in which A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 and A 8 are each independently C 1 -C 12 -alkyl or C 2 -C 12 -alkenyl, C 4 -C 8 -cycloalkyl, C 6 -C 12 -aryl, C 7 -C 12 -aralkyl, or A 1 A 2 , A 3 A 4 , A 5 A 6 and A 7 A 8 are each independently joined to one another directly or via O or N-A 9 to give a 3- to 7-membered ring, A 9 is C 1 -C 4 -alkyl, Y − is a monobasic acid radical or the equivalent of a polybasic acid radical, or (C) a compound of the formula (V) in which A 10 and A 11 are each independently one of the following radicals R 7 , R 8 , R 9 , R 10 , R 11 and R 12 are each independently C 1 -C 10 -alkyl, C 2 -C 10 -alkenyl or C 6 -C 12 -aryl, or R 7 R 6 , R 9 R 10 , R 11 R 12 are each independently joined directly to one another to give a 3- to 5-membered, saturated or unsaturated ring which contains one nitrogen atom and otherwise carbon atoms, where the radical may also be a saturated or unsaturated, 4- to 8-membered ring which contains two nitrogen atoms and otherwise carbon atoms, Z − is an equivalent of an anion, or (D) a hexaalkylguanidinium salt of the formula (VI) in which A 12 , A 13 , A 14 , A 15 , A 16 and A 17 are each independently C 1 -C 12 -alkyl or C 2 -C 12 -alkenyi, C 4 -C 8 -cycloalkyl, C 6 -C 12 -aryl, C 7 -C 12 -aralkyl, or A 12 A 13 , A 14 A 16 and A 16 A 17 are each independently joined to one another directly or via O or N-A 18 to give a 3- to 7-membered ring, A 18 is C 1 -C 4 -alkyl, (Z 1 ) − is one equivalent of an anion, in the presence of a polyether of the formula (VII) R 13 —(O—C m H 2m ) r —OR 14 (VII) in which R 13 and R 14 are each independently C 1 -C 16 -alkyl, m is an integer from 2 to 6, r is an integer from 0 to 20, and in the presence of catalytic amounts of a protic compound selected from the group consisting of sulpholane, dimethyl sulphoxide (DMSO), dimethylacetamide, dimethylformamide (DMF), N-methylpyrrolidone (NMP), 1,3-dimethylimidazolinone, HF, water, dichloromethane, chloroform, dichloroethane, trichloroethane, ketones nitriles, and amides.