- Method for producing 1 substituted 5-chloro-4 methly pyrazoles
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The present invention relates to a process for preparing 1-substituted 5-chloro-4-methylpyrazoles of the general formula I with the meaning for R stated in claim 1, in which a 4-methylpyrazole of the formula II is reacted with chlorine, the resulting mixture of monochlorinated and dichlorinated product is fractionated by distillation, and subsequently the dichlorinated compound is dehalogenated to compound II and returned to the reaction with chlorine.
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- Method for producing N-substituted 2-pyrazoline-5-one
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The present invention relates to a process for preparing N-substituted 2-pyrazolin-5-ones of the formula I where R has the meaning given in claim 1, which comprises reacting a compound of the formula II where R, X and Y have the meanings given in claim 1, at elevated temperature with a molar excess of alkali metal hydroxide in an aqueous reaction medium and then adjusting the pH to pH≦6 by adding an acid.
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- Selective N-methylation of pyrazolone with methanol by use of ZrO2 catalyst in the liquid phase
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Selective methylation of pyrazolone to 1-methylpyrazolone was investigated with ZrO2, which is a representative metal oxide with amphoteric character. The high selectivity up to ~7% was obtained at 503 K. Mechanism is proposed in view of weak acidic-moderately basic pair sites of ZrO2.
- Shinoda, Sumio,Shima, Satoru,Yamakawa, Tetsu
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p. 809 - 810
(2007/10/03)
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- Intramolecular Hetero-Diels-Alder Reaction of Alkylidene- and Benzylidenepyrazolones and Benzylideneisoxazolones. Investigations toward the Conformation of the Transition State
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Stereochemical aspects of the intramolecular hetero-Diels-Alder reaction of hetero dienes are studied.Knoevenagel condensation of aromatic aldehydes 1, 12, 15,, and 21 with pyrazolones 8a-h and isoxazolone 17 gave the corresponding hetero dienes, e.g.,9a-
- Tietze, Lutz F.,Brumby, Thomas,Pretor, Martina,Remberg, Gerd
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p. 810 - 820
(2007/10/02)
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- REGIOSELECTIVE NUCLEOPHILIC SUBSTITUTION IN ACTIVATED 1-AMINOPYRAZOLIUM CATIONS: A FACILE SYNTHESIS OF 5-SUBSTITUTED 1-METHYLPYRAZOLES
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5-Substituted 1-methylpyrazoles were easily obtained in good yields by the attack of nucleophiles (NaCN, H2O, EtSH, pyrazole, imidazole) to 2,6-dimethyl-1-(2-methylpyrazol-1-io)-4-phenylpyridinium bistetrafluoroborate (1b), without significant formation o
- Bruix, Marta,Castellanos, M. Luisa,Martin, M. Rosario,Mendoza, Javier de
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p. 5485 - 5488
(2007/10/02)
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