Benzil Property

Melting point:

94-95 °C(lit.)

Boiling point:

346 °C

Density 

1,521 g/cm³

vapor pressure 

1 mm Hg ( 128.4 °C)

refractive index 

1.5681 (estimate)

Flash point:

346-348°C

storage temp. 

Store below +30°C.

solubility 

<0.5g/l

form 

Crystalline Powder

color 

White

Water Solubility 

0.5 g/L (20 ºC)

Merck 

14,1078

BRN 

608047

Dielectric constant

13.0（94℃）

Stability:

Stable. Combustible. Incompatible with strong oxidizing agents.

InChIKey

WURBFLDFSFBTLW-UHFFFAOYSA-N

CAS DataBase Reference

134-81-6(CAS DataBase Reference)

NIST Chemistry Reference

Ethanedione, diphenyl-(134-81-6)

EPA Substance Registry System

Benzil (134-81-6)

Safety

Hazard Codes 

Xi

Risk Statements 

36/37/38

Safety Statements 

26-36-37/39

WGK Germany 

2

RTECS 

DD1925000

F 

10

Hazard Note 

Irritant

TSCA 

Yes

HS Code 

29143900

Toxicity

LD50 orally in Rabbit: 2710 mg/kg

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P302+P352IF ON SKIN: wash with plenty of soap and water.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P332+P313IF SKIN irritation occurs: Get medical advice/attention.

P337+P313IF eye irritation persists: Get medical advice/attention.

Benzil Chemical Properties,Usage,Production

Description

Benzil (134-81-6) also known as 1,2-diphenylethane-1,2-dione is an organic compound with the molecular formula (C6H5CO)2. The compound belongs to the group of organic compounds known as stilbenes which contains a 1,2-diphenylethylene moiety. Benzyl is yellow in color and is one of the most common diketones.

Structure

The most noticeable feature in Benzil&rsquo;s structure is the long carbon-carbon bond of 1.54 &Aring;, which shows there is no pi-bonding between the two carbonyl centers. Although the par of benzoyl groups are twisted with respect to the other with a dihedral angler of 117o, the PhCO are planar.

Preparation

Benzyl is synthesized from benzoin, for instance with copper (II) acetate.
PhC(O)CH(OH)Ph + 2 Cu2+ → PhC(O)C(O)Ph + 2 H+ + 2 Cu+

Applications

Benzil is utilized as an intermediate in pharmaceuticals and UV curing resin photosensitizer. Benzyl is mostly used in the free-radical curing of polymer networks. Benzyl is decomposed by ultraviolet radiation that generates free-radical species within the material, leading to the formation of cross-links. It is normally employed as a photoinitiator in polymer chemistry. In addition, Benzil is a potent inhibitor of human carboxylesterases, which are enzymes involved in the hydrolysis of many drugs used clinically as well as carboxylesters. It is also used in the synthesis of diketimines by reaction with amines. Benzyl is also used as an intermediate in the famous benil-benzilic acid arrangement. Further, it reacts with 1,3-diphenylacetone to get tetraphenylcyclopentadienone.

Chemical Properties

yellow crystals or powder

Uses

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.

Reactions

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).

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 Profile

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

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.

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).