3,5-Dimethylpyrazole

Chemical properties

White crystal powder

The Uses of 3,5-Dimethylpyrazole

3,5-Dimethylpyrazole is used as intermediate for the manufacture of organic dyestuffs and photochemicals. It is a catalyst in the sulfonation of acetic anhydride to sulfoacetic acid and methanedisulfonic acid. 3,5-Dimethylpyrazole has been used to synthesise bipyrazolic tripodal derivatives with in vitro antitumor, antifungal and antibacterial activities. Standard reagent for the preparation of pyrazolato-ligated complexes. Also used to prepare N-1-substituted derivatives having antibacterial activity.

Synthesis Reference(s)

Journal of Heterocyclic Chemistry, 19, p. 373, 1982 DOI: 10.1002/jhet.5570190231
Organic Syntheses, Coll. Vol. 4, p. 351, 1963

Description

3,5-Dimethylpyrazole is an important fine chemical product with high added value. It was recently used as the ligand to study the synthesis and structure of trimethylacetato complexes of zinc, copper, nickel, and cobalt. And more, 3,5-dimethylpyrazole is a most satisfactory reagent for the gravimetric determination of cobalt. As a hypoglycemic agent, 3,5-dimethylpyrazole was found to be fifty-four times more potent orally than tolbutamide in glucose-injected, fasted-intact rats. In addition, the use of 3,5-dimethylpyrazole as a blocking agent for isocyanates is known. With 3,5-dimethylpyrazole blocked lacquer polyisocyanates can be used as crosslinkers in high-quality one-component polyurethane coating binders. The advantage of 3,5-dimethylpyrazole over other blocking agents, such as butanone oxime, is in a much lower thermal yellowing of the coatings and a relatively low firing temperature of about 130 °C.

Synthesis

3,5-Dimethylpyrazole has been prepared from acetylacetone and hydrazine hydrate in ethanol or hydrazine sulfate in aqueous alkali. The latter method is preferred because the reaction with hydrazine hydrate is sometimes violent. 3,5-Dimethylpyrazole also has been prepared by hydrolysis and decarboxylation of the 1-carbamide- or 1-carboxamidine derivatives, obtained by reaction of semicarbazide or aminoguanidine with acetylacetone and from 1,2-pentadien-4-one and hydrazine hydrate.

Purification Methods

Crystallise it from cyclohexane or water. [Barszez et al. J Chem Soc, Dalton Trans 2025 1986, Beilstein 23/5 V 110.]