Method for producing substituted pyrazolecarboxylic acid chlorides
View Patent ↗The present invention relates to a process for preparing substituted pyrazolyl chlorides by chlorinating aldehydes of the formula (II) under free-radical conditions.
1. Process for preparing substituted pyrazolecarbonyl chlorides of formula (I)
in which
R 1 is hydrogen, alkyl, alkoxyalkyl, unsubstituted or substituted aryl, unsubstituted or substituted aralkyl, unsubstituted or substituted heteroaryl and haloalkyl,
R 2 is hydrogen, halogen, alkyl, alkoxyalkyl, unsubstituted or substituted aryl, unsubstituted or substituted aralkyl, unsubstituted or substituted heteroaryl and haloalkyl,
X is fluorine, chlorine or bromine,
comprising reacting in aldehyde of formula (II)
with a chlorinating agent under free-radical conditions.
2. Process according to claim 1 , where
R 1 is C 1 - to C 3 -alkyl,
R 2 is hydrogen, halogen, alkyl and haloalkyl, and
X is chlorine, bromine or fluorine.
3. Process according to claim 1 , wherein
R 1 is methyl,
R 2 is methyl and
X is chlorine or fluorine.
4. Process according to claim 1 , wherein the free-radical conditions are generated by the presence of a free-radical initiator or by irradiation.
5. Process according to claim 1 , wherein the reaction is performed in the presence of an acid scavenger.
6. Process according to claim 1 , wherein the reaction is performed in the presence of an aqueous base.
7. Process according to claim 2 , wherein
R 1 is methyl,
R 2 is methyl and
X is chlorine or fluorine.
8. Process according to claim 2 , wherein the free-radical conditions are generated by the presence of a free-radical initiator or by irradiation.
9. Process according to claim 3 , wherein the free-radical conditions are generated by the presence of a free-radical initiator or by irradiation.
10. Process according to claim 2 , wherein the reaction is performed in the presence of an acid scavenger.
11. Process according to claim 3 , wherein the reaction is performed in the presence of an acid scavenger.
12. Process according to claim 4 , wherein the reaction is performed in the presence of an acid scavenger.
13. Process according to claim 2 , wherein the reaction is performed in the presence of an aqueous base.
14. Process according to claim 3 , wherein the reaction is performed in the presence of an aqueous base.
15. Process according to claim 4 , wherein the reaction is performed in the presence of an aqueous base.
16. Process according to claim 5 , wherein the reaction is performed in the presence of an aqueous base.