- 4-methylpyrazole preparation method
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The invention discloses a 4-methylpyrazole preparation method. According to the preparation method, 3-amino-2-methylacrolein and formamide are utilized as main raw materials, methylbenzene is utilized as solvent, 4-methylpyrazole is prepared through normal-pressure reaction, and a 4-methylpyrazole finished product can be prepared by rectifying a crude product. The preparation method is simple, has moderate reaction conditions and avoids high-pressure reaction; the main raw materials are safe and environment-friendly; the product has high purity and is more favorable for industrial production.
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Paragraph 0018; 0019; 0020
(2017/07/22)
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- ULTRAPURE 4-METHYLPYRAZOLE
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Disclosed is an ultrapure 4-methylpyrazole containing less than 0.1% pyrazole and containing less than 10 ppm each of hydrazine and nitrobenzaldehyde. The ultrapure 4-methylpyrazole is prepared by a novel process so that less than 0.01% of ethylvinyl ether is present.
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Page/Page column 2; 3
(2008/06/13)
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- ULTRAPURE 4-METHYLPYRAZOLE
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Disclosed is an ultrapure 4-methylpyrazole containing less than 0.1% pyrazole and containing less than 10 ppm each of hydrazine and nitrobenzaldehyde. The ultrapure 4-methylpyrazole is prepared by a novel process so that less than 0.01% of ethylvinyl ether is present.
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Page/Page column 8-9
(2008/06/13)
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- Method for producing substituted pyrazoles
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Pyrazole derivatives are prepared by reacting carbonyl compounds R1—C(O)—CH(R2)—CH2R3with hydrazine, its hydrate or its salts in 30 to 100% by weight sulfuric acid in the presence of catalytic amounts of iodine or of an iodine compound.
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- Preparation of pyrazole and its derivatives
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A process for preparing pyrazole and its derivatives of the formula I STR1 where R1, R2, R3 and R4 are each hydrogen, halogen, nitro, carboxyl, sulfonyl or C-organic radicals, from alpha,beta-unsaturated carbonyl compounds of the formula II STR2 and hydrazine or hydrazine derivatives of the formula III wherein, initially without additional diluent, an alpha,beta-unsaturated carbonyl compound of the formula II is reacted with hydrazine or a hydrazine derivative of the formula III, and the resulting reaction mixture is reacted in another step with a mixture of sulfuric acid and iodine or a compound which liberates iodine or hydrogen iodide.
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- THE NITROGENATED ALLYLIC SYSTEM AS AN INTRAMOLECULAR NUCLEOPHILE: A NEW ROUTE TO PYRAZOLES
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A new route to pyrazoles via the cyclization of N-allyl-N-nitrosoamides is described.
- Momose, Takefumi,Toyooka, Naoki,Ikuta, Takashi,Yanagino, Hironobu
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p. 789 - 793
(2007/10/02)
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- NEW METHODS AND REAGENTS IN ORGANIC SYNTHESIS. 41. LITHIUM TRIMETHYLSILYLDIAZOMETHANE. A NEW SYNTHON FOR THE PREPARATION OF PYRAZOLES FROM α,β-UNSATURATED NITRILES
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Lithium trimethylsilyldiazomethane reacts smoothly with various α,β-unsaturated nitriles to give 3(or 5)-trimethylsilylpyrazoles in good yields.
- Aoyama, Toyohiko,Inoue, Sumie,Shioiri, Takayuki
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p. 433 - 436
(2007/10/02)
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