METHOD FOR PRODUCING 1-SUBSTITUTED 5- OR 3-HYDROXYPYRAZOLES

摘要

1. A process for preparing a 1-substituted 5- and/or 3-hydroxypyrazole of the formulae I and II, respectively in which R<1> is C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C3-C6-cycloalkyl or C1-C4-alkoxy, where these groups may be substituted by halogen, C1-C4-alkoxy, phenoxy, C1-C6-alkoxycarbonyl, C1-C6-alkylthiocarbonyl or by a cyclic ring system having 3-14 ring atoms, which comprises reacting c) an alkyl vinyl ether of the formula V in which R<2> is C1-C6-alkyl or C3-C6-cycloalkyl with phosgene VIa, "diphosgene" VIb or "triphosgene" VIc to give an acyl chloride of the formula VII d) converting this by elimination of hydrogen chloride into the corresponding 3-alkoxyacryloyl chloride of the formula VIII and e) esterifying this with an alcohol of the formula IX in which R<3> is C1-C6-alkyl or C3-C6-cycloalkyl to give the corresponding alkyl 3-alkoxyacrylate of the formula III, and reacting said alkyl 3-alkoxyacrylate of the formula III with a hydrazine of the formula IV in which R<1> is as defined above a) at a pH of 6-11 to give 5-hydroxypyrazoles of the formula I or b) at a pH of 11-14 to give 3-hydroxypyrazoles of the formula II. 2. A process as claimed in claim 1, wherein the reaction in step a) is carried out at from -30 degree C to 100 degree C. 3. A process as claimed in claim 1, wherein the reaction is carried out in the presence of a base. 4. A process as claimed in claim 1, wherein the base used is an alkali metal hydroxide, alkaline earth metal hydroxide or tertiary amine. 5. A process as claimed in claim 2, wherein a solvent is initially charged and the alkyl 3-alkoxyacrylate III and the hydrazine IV are simultaneously metered into the solvent. 6. A process as claimed in claim 5, wherein the solvent used is water, an alcohol, ether or a mixture of these. 7. A process as claimed in claim 1, wherein the reaction in step b) is carried out at from -30 degree C to 100 degree C. 8. A process as claimed in claim 7, wherein the reaction is carried out in the presence of a base. 9. A process as claimed in claim 8, wherein the base used is an alkali metal hydroxide, alkaline earth metal hydroxide, a tertiary amine or a mixture of these. 10. A process as claimed in claim 1, wherein the reaction in step c) is carried out at from -78 degree C to 100 degree C. 11. A process as claimed in claim 1, wherein the alkyl vinyl ether V is reacted with phosgene VIa, diphosgene VIb or triphosgene VIc in a molar ratio of from 0.1:1 to 1:1. 12. A process as claimed in claim 1, wherein the reaction in step d) is carried out at from 30 degree C to 80 degree C. 13. A process as claimed in claim 1, wherein the esterification in step e) is carried out at from -20 degree C to 80 degree C.