Benzil

Chemical properties

yellow crystals or powder

The Uses of Benzil

Organic synthesis; insecticide.

The Uses of Benzil

Benzil is used as a pharmaceutical intermediate and uv curing resin photosensitizer. In polymer chemistry, it is used as a photoinitiator. Further, it serves as a potent inhibitor of human carboxylesterases. It is used in the preparation of diketimines by reacting with amines. It is also involved in the famous benil-benzilic acid rearrangement. In addition this, it reacts with 1,3-diphenylacetone to get tetraphenylcyclopentadienone.

Definition

A reaction in which benzil (1,2- diphenylethan-1,2-dione) is treated with hydroxide and then with acid to give benzilic acid (2-hydroxy-2,2-diphenylethanoic acid):
C₆H₅.CO.CO.C₆H₅→
(C₆H₅)₂C(OH).COOH
The reaction, which involves migration of a phenyl group (C₆H₅-) from one carbon atom to another, was the first rearrangement reaction to be described (by Justus von Liebig in 1828).

Definition

ChEBI: An alpha-diketone that is ethane-1,2-dione substituted by phenyl groups at positions 1 and 2 respectively.

Benefits

Benzil has potential applications in biological metabolism and clinical medicine. Benzil derivates exhibit radical scavenging and antibacterial and hypertensive, antiprotozoal, antiproliferative, and antimitotic activities. Benzil derivatives have versatile applications in the pharmaceutical industry, and various heterocyclic compounds such as triazine, quinoxaline, and imidazole can be synthesized from 1,2-diketones. It is also used as a nanocatalyst in the application of imidazole derivatives. Recently, it is reported that benzil derivatives acted as photosensitive agents and photoinitiators due to its antitumor activity[1].

Synthesis Reference(s)

Journal of the American Chemical Society, 105, p. 7755, 1983 DOI: 10.1021/ja00364a054
Tetrahedron Letters, 30, p. 6267, 1989 DOI: 10.1016/S0040-4039(01)93869-9

Safety

Potential Acute Health Effects: Very hazardous in case of skin contact (irritant), of eye contact (irritant). Hazardous in case of ingestion, of inhalation.
The substance is toxic to lungs, mucous membranes. Repeated or prolonged exposure to the substance can produce target organs damage. Eye Contact: Check for and remove any contact lenses.
Fine dust dispersed in air may ignite. Dust can form an explosive mixture in air. Thermal decomposition can lead to release of irritating gases and vapors. Keep product and empty container away from heat and sources of ignition.

Safety Profile

Low toxicity by ingestion. An eyeirritant. Combustible. When heated to decomposition itemits acrid smoke and irritating fumes.

Solubility in organics

Soluble in ethanol (50 mg/ml), chloroform, ether, and ethyl acetate. Insoluble in water.

Purification Methods

Crystallise benzil from *benzene after washing with alkali. (Crystallisation from EtOH did not free benzil from material reacting with alkali.) [Hine & Howarth J Am Chem Soc 80 2274 1958.] It has also been crystallised from CCl4, diethyl ether or EtOH [Inoue et al. J Chem Soc, Faraday Trans 1 82 523 1986]. [Beilstein 7 IV 2502.]

References

[1] N. Kanagathara. “Structural and Vibrational Investigation of Benzil-(1,2-Diphenylethane-1,2-Dione): Experimental and Theoretical Studies.” New Journal of Chemistry 3 1 (2022).