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Pyrazole-4-carbaldehyde Vilsmeier-Haack reaction

The corresponding 4-halopyrazoles are produced by the action of chlorine or bromine in acetic acid. Nitrating acid yields 4-nitropyrazoles and, dependent on the substituents in the pyrazole ring, reaction takes place either with pyrazole itself or the pyrazolium ion. Sulfonation involves the pyrazolium ion. For this reason, heating in oleum is necessary, which leads to pyrazole-4-sulfonic acid. Pyrazoles with substituents in the 1-position yield pyrazole-4-carbaldehyde in the Vilsmeier-Haack formylation and are amenable to Friedel-Crafts acylation. 4- and 5-aminopyrazoles can be diazotized. [Pg.182]


See other pages where Pyrazole-4-carbaldehyde Vilsmeier-Haack reaction is mentioned: [Pg.53]   
See also in sourсe #XX -- [ Pg.791 ]

See also in sourсe #XX -- [ Pg.791 ]

See also in sourсe #XX -- [ Pg.791 ]




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Carbaldehyde

Carbaldehydes

Haack

Haack Reaction

Pyrazole reactions

Pyrazole-4-carbaldehyde

Pyrazoles Vilsmeier-Haack reaction

Vilsmeier

Vilsmeier-Haack

Vilsmeier-Haack reaction

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