1,1-DIPHENYLHYDRAZINE

Description

Diphenylhydrazine is a man-made chemical that occurs in two isomeric forms: 1,1-diphenylhydrazine and 1,2-diphenylhdrazine. Diphenylhydrazine is produced by the reduction of nitrobenzene. Little or no information is available for 1,1-diphenylhydrazine. Most toxicological and use data pertain to 1,2-diphenylhydrazine.

The Uses of 1,1-DIPHENYLHYDRAZINE

Previously, 1,2-diphenylhydrazine was used for producing benzidine that was used in the synthesis of benzidine-based dyes. However, these dyes are no longer produced in the United States. The primary use of 1,2-diphenylhydrazine is in the production of the anti-inflammatory agent phenylbutazone and sulfinpyrazone, a uricosuric agent.

Synthesis Reference(s)

The Journal of Organic Chemistry, 33, p. 3963, 1968 DOI: 10.1021/jo01274a068

General Description

Yellow crystals. Insoluble in water.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Toxic gases may be formed by mixing 1,1-DIPHENYLHYDRAZINE with acids, aldehydes, amides, carbamates, cyanides, inorganic fluorides, halogenated organics, isocyanates, ketones, metals, nitrides, peroxides, phenols, epoxides, acyl halides, and strong oxidizing or reducing agents. Flammable gases are formed by mixing materials in this group with alkali metals. Explosive combination can occur with strong oxidizing agents, metal salts, peroxides, and sulfides.

Environmental Fate

Definitive information regarding the environmental fate and behavior of diphenylhydrazine in environmental media is extremely limited. No information is available affirming persistence of diphenylhydrazine in the environment or definitive pathways for its degradation. The low vapor pressure of diphenylhydrazine precludes it being a significant air contaminant. Diphenylhydrazine may be moderately absorbed into soil but it would be quickly oxidized to azobenzene. The half-life of diphenylhydrazine in water is reportedly less than 15 min and is likely due to its oxidation to azobenzene and benzidine.

Purification Methods

Purify it via the hydrochloride [530-47-2], which has m 165-170o(dec) after crystallization from aqueous EtOH (+ a few drops of HCl) and recover the free base with aqueous NaOH, extract it into Et2O, dry it (KOH), filter, evaporate and distil the residue under a vacuum. The distillate crystallises on cooling. The benzoyl derivative has m 194o (from Me2CO), and the 4-nitrophenyl hydrazone (with the aldehyde) has m 131-132o. [Koga & Anselme J Org Chem 33 3963 1968, Beilstein 15 IV 55.]

Toxicity evaluation

The mechanism of action of diphenylhydrazine is not known. It is possible that some toxic effects may be attributed to its major metabolites, aniline and azobenzene, both of which are known carcinogens. Results of metabolism studies reporting aniline, benzidine, hyroxybenzidines, and aminophenols as metabolites in rats following multiple routes of administration suggest that the diphenylhydrazine metabolism may be similar to that of azobenzene and aniline. It is also possible that conversion of 1,2-diphenylhydrazine to aniline in the gastrointestinal tract may occur due to intestinal microflora and via acid hydrolysis.