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Volume :3 Issue : 1 1976      Add To Cart                                                                    Download

Reactions of 5-pyrazolone derivatives

Auther : FAROUK H. AL-HAJJAR

Department of Chemistry, University of Kuwait

 

ABSTRACT

 

Methylation of 3-aryl-5-pyrazolones (3-aryl-5-hydroxypyrazoles) (Ia, Ib and Ic) with diazomethane or dimethyl sulphate in neutral and alkaline media has been studied. (Ia) also reacted with 2,4,4,6-tetrabromocyclohexa-2,5-dien-1- one to give the 4-bromo derivative (V), which upon methylation with diazomethane or acetylation gave the corresponding 4-bromo- 5-methoxy-(VIa) or 1-acetyl-5-acetoxy-4-bromo (VIIIa)-3-phenylpyrazole, respectively. Reaction of the diazonium salts of aniline and benzidine with (Ia) has been studied. When the benzeneazo derivative (X) was reacted with dimethyl sulphate, acetic anhydride, and bromine in aqueous potassium bromide solution, it gave the corresponding I-methyl-(XII) and 1-acetyl-(XV)-pyrazole derivatives and 4-(p-bromobenzeneazo)-3 phenylpyrazolone (XI), respectively. Reaction of (Ia) with chloroform in the presence of sodium hydroxide gave (XVIII), which upon treatment with acetic anhydride, gave the N-acetyl derivative (XIX). Reaction of 2, 3-diphenyl-5 hydroxypyrazol (XX) with diazomethane gave the corresponding 5-methoxy derivative (XXI). When this compound was brominated, it gave the 4-bromo-5-methoxy-derivative (XXII).

 

 

 

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