O-Tolidine

Description

o-Tolidine, also called orthotolidine or 2-tolidine, is a chemical compound with the molecular formula (C6H4(CH3)NH2)2. It is a white to reddish-colored, combustible, aromatic amine that emits toxic fumes of nitrogen oxides when heated to decomposition. Several isomers are known; the 3-tolidine derivative is also important commercially. It is a colorless compound although commercial samples are often colored. It is slightly soluble in water. It forms salts with acids, such as hydrochloride, which is commercially available. 2-Tolidine can be produced by a benzidine rearrangement from a hydrazine derivative derived from 2-nitrotoluene.

Chemical properties

o-Tolidine is a white to reddish crystal or powder and has an aniline-like odor. It is soluble in alcohol, ether, and dilute acid, but only slightly soluble in water. It has a tendency to darken when exposed to air and is commonly utilized in paste or wet cake form. This compound serves as a fundamental component for the production of numerous dyes.

The Uses of O-Tolidine

o-Tolidine is used extensively in the manufacture of dyes. It is also used as a reagentfor the analysis of gold and free chlorine inwater.

The Uses of O-Tolidine

3,3'-Dimethylbenzidine be used for preparation polyimide and epoxy resin material.

Preparation

There are two commonly used methods for producing o-Tolidine. The first method involves reducing ortho-nitrotoluene to 1,2-diorthotolylhydrazine, which is then rearranged with acid. The second method involves reducing o-nitrotoluene using zinc dust and caustic soda, then converting the resulting hydrazotoluene to o-Tolidine by boiling it with hydrochloric acid. Once either of these methods is completed, o-Tolidine can be extracted and purified through techniques such as solvent extraction and recrystallization.

Definition

ChEBI: 3,3'-Dimethylbenzidine is a member of biphenyls.

General Description

3,3'-dimethylbenzidine appears as white to reddish crystals or crystalline powder or a light tan powder. (NTP, 1992)

Air & Water Reactions

Insoluble in water.

Reactivity Profile

C.I. 37230 is sensitive to exposure to light. May be sensitive to prolonged exposure to air. A weak base that forms salts with hydrochloric acid or sulfuric acid. C.I. 37230 can be acetylated. Incompatible with strong agents .

Hazard

Eye, bladder and kidney irritant, bladder cancer, and methemoglobinemia. Possible carcinogen.

Health Hazard

The information on toxicity and carcinogenicity of o-tolidine is very little. o-Tolidineoften contains other biphenylamine contaminants. Its structure and chemical propertiesare similar to those of benzidine. The toxicproperties are therefore expected to be similar to those of benzidine.
o-Tolidine is absorbed into body throughthe skin, respiratory, and gastrointestinaltract. The acute oral and dermal toxicity wasmoderate in experimental animals. An oralLD50 value in rats is within the range of400 mg/kg.
o-Tolidine produced bladder cancer in testspecies. Also, cancers in other tissues werenoted in some animals. ACGIH lists thissubstance as a suspected human carcinogen.

Fire Hazard

Flash point data for C.I. 37230 are not available; however, C.I. 37230 is probably combustible.

Safety Profile

Confirmed carcinogen with experimental carcinogenic and tumorigenic data. Poison by intraperitoneal route. Moderately toxic by ingestion. Human mutation data reported. When heated to decomposition it emits toxic fumes of NOx.

Potential Exposure

Over 75% of o-tolidine is used as a dye and as an intermediate in the production of rubber products, dyestuffs, pigments and pesticides. Approximately 20% of o-tolidine is used in the production of polyurethane-based high-strength elastomers, coatings, and rigid plastics. o-Tolidine has also been used in small quantities in chlorine test kits by water companies and swimming pool owners. Used as a laboratory agent to detect blood.

Carcinogenicity

3,3′-Dimethylbenzidine is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.

Shipping

UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required. UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required.

Purification Methods

Dissolve the tolidine in *benzene by percolation through a column of activated alumina and crystallise it from *benzene/pet ether. [Beilstein 13 IV 410.]

Incompatibilities

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, strong reducing agents.

Waste Disposal

Dissolve in flammable solvent and spray into firebox of an incinera tor equipped with afterburner and scrubber. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.