Azobenzene Chemical Properties

Melting point:

65-68 °C (lit.)

Boiling point:

293 °C (lit.)

Density 

1.09 g/mL at 25 °C (lit.)

vapor pressure 

1 mm Hg ( 104 °C)

refractive index 

1.62662 (78.1℃)

Flash point:

100 °C

storage temp. 

room temp

solubility 

6.4mg/l

form 

Crystalline Powder

color 

Orange

Water Solubility 

Soluble in alcohol, ether, benzene and glacial acetic acid. Insoluble in water.

Merck 

14,917

BRN 

1819138

Stability:

Stable. Combustible. Incompatible with strong oxidizing agents. Air and light sensitive.

CAS DataBase Reference

103-33-3(CAS DataBase Reference)

IARC

3 (Vol. 8, Sup 7) 1987

EPA Substance Registry System

Azobenzene (103-33-3)

Safety Information

Hazard Codes 

T,N,Xn,F

Risk Statements 

45-20/22-48/22-50/53-68-67-65-62-51/53-38-11-48/20-39/23/24/25-23/24/25-52/53

Safety Statements 

53-45-60-61-62-36/37-33-29-16-9-7

RIDADR 

UN 3077 9/PG 3

WGK Germany 

3

RTECS 

CN1400000

Autoignition Temperature

890 °F

TSCA 

Yes

HazardClass 

6.1(b)

PackingGroup 

III

HS Code 

29270000

Hazardous Substances Data

103-33-3(Hazardous Substances Data)

Toxicity

LD50 orally in Rabbit: 1000 mg/kg

MSDS

• Language:English Provider:ACROS
• Language:English Provider:SigmaAldrich
• Language:English Provider:ALFA

Azobenzene Usage And Synthesis

Description

Azobenzene is a well-known derivative of stimulus-responsive molecular switches and has shown superior performance as a functional material in biomedical applications.
Azobenzene is a typical photo-responsive molecule that isomerizes from its planar trans-form to the non-planar cis-form after UV-light irradiation with a wavelength between 300 nm and 400 nm (lmax is around 330 nm). Interestingly, the system reverts from the cis-form to the trans-form after further irradiation with visible light (wavelength over 400 nm). This process is completely reversible, and the azobenzene group does not decompose or induce undesirable side reactions even on repeated trans-cis isomerization. By introducing azobenzenes into DNA through D-threoninol as a linker, Asanuma and co-workers succeeded in achieving photo-regulation of:
Formation and dissociation of a DNA duplex
Transcription by T7-RNA polymerase reaction

Chemical Properties

Azobenzene is a combustible, orange-red crystalline solid.

Chemical Properties

orange to red crystals

Uses

Impurity in the production of Phenylbutazone (P319570).

Uses

acaricide, insecticide.
Azobenzene can be used as an optical trigger for the design and synthesis of a large variety of photoresponsive systems.

Uses

Precursor for dyes, for polymers.

Definition

ChEBI: A molecule whose structure comprises two phenyl rings linked by a N=N double bond; the parent compound of the azobenzene class of compounds.

Synthesis Reference(s)

Canadian Journal of Chemistry, 38, p. 2526, 1960 DOI: 10.1139/v60-344
Chemical and Pharmaceutical Bulletin, 36, p. 1529, 1988 DOI: 10.1248/cpb.36.1529
Tetrahedron Letters, 25, p. 1259, 1984 DOI: 10.1016/S0040-4039(01)80128-3

General Description

Orange-red crystals or dark brown chunky solid.

Air & Water Reactions

AZOBENZENE is sensitive to air and light. Dust may form an explosive mixture in air. Insoluble in water.

Reactivity Profile

AZOBENZENE is an azo compound. Azo, diazo, azido compounds can detonate. This applies in particular to organic azides that have been sensitized by the addition of metal salts or strong acids. Toxic gases are formed by mixing materials of this class 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. AZOBENZENE is incompatible with strong oxidizing agents.

Hazard

Toxic; may cause liver injury. Questionable carcinogen.

Fire Hazard

Flash point data for AZOBENZENE are not available. AZOBENZENE is probably combustible.

Safety Profile

Moderately toxic by ingestion and possibly other routes. Questionable carcinogen with experimental carcinogenic, neoplastigenic, and tumorigenic data. When heated to decomposition it emits toxic fumes of NOx.

Potential Exposure

An azo compound. Those engaged in azobenzene use in dye, rubber, chemical, and pesticide manufacturing.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.

storage

lor Code—Blue: Health Hazard/Poison: Storein a secure poison location. Prior to working with thischemical you should be trained on its proper handling andstorage. Store under an inert atmosphere in a freezer orAzobenzene 301refrigerator. Protect from air and light. Sources of ignition, such as smoking and open flames, are prohibitedwhere this chemical is used, handled, or stored in a mannerthat could create a potential fire or explosion hazard. Aregulated, marked area should be established where thischemical is handled, used, or stored in compliance withOSHA Standard 1910.1045.

Shipping

UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.

Purification Methods

Ordinary azobenzene is nearly all in the trans-form. It is partly converted into the cis-form on exposure to light [for isolation see Hartley J Chem Soc 633 1938, and for spectra of cis-and trans-azobenzenes, see Winkel & Siebert Chem Ber 74B 6701941]. trans-Azobenzene is obtained by chromatography on alumina using 1:4 *C6H6/heptane or pet ether, and it crystallises from EtOH (after refluxing for several hours) or hexane. All operations should be carried out in diffuse red light or in the dark. [Beilstein 16 IV 8.]

Incompatibilities

Azo compounds can detonate. This applies in particular to organic azides that have been sensitized by the addition of metal salts or strong acids. Toxic gases are formed by mixing materials of this class 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. This chemical is sensitive to prolonged exposure to heat. This chemical is incompatible with strong oxidizing agents.

Azobenzene(103-33-3)Related Product Information

• 3,3'-AZODIBENZOIC ACID
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• 4,4'-AZODIBENZOIC ACID DIETHYL ESTER
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• AZOBENZENE-4,4'-DICARBOXYLIC ACID DIMETHYL ESTER
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• Solvent Red 27
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• ACID RED 66