Overview
O-nitrotoluene is also known as 2-nitrotoluene or 1-methyl-2-nitrobenzene，and is yellow oily transparent liquid. It has the smell of nitrobenzene. The relative density is 1.1629. The melting point is-2.9℃ (α-type, stable type),-9.5℃ (β-type, non-stable type). The boiling point is 221.7 °C, 118 °C (2.133×103Pa) and 50.0 °C (0.133×103Pa). The flash point is 106.1 °C (closed system). The refractive index is 1.5450. The viscosity is 0.0262 mPa•s (15℃). The vapor pressure (×103 Pa) is 10.906 (5℃), 12.639 (10℃), 14.612 (20℃), 15.892 (30℃). It is slightly soluble in water (0.061 at 30°C), soluble in benzene, chloroform and petroleum ether and immiscible with ethanol and ether. It can evaporate together with water vapor. Due to the strong electron-withdrawing ability of nitro group, the methyl of is easy to be oxidized to form o-nitrobenzaldehyde or o-nitrobenzoic acid according to oxidation conditions. And o-nitrotoluene can be reduced in the presence of catalyst to generate o-toluidine, which can generate 2,4 or 2,6 dinitrotoluene after further nitration. O-nitrotoluene can also be chlorinated to generate nitrobenzyl chloride. In addition, o-nitrotoluene can also generate azo compounds. LD50 (rat oral) is 801mg/kg.
O-nitrotoluene is mainly used as the raw material of dyestuffs to prepare 4-chloro-2-nitrotoluene, 6-chloro-2-nitrotoluene, o-toluidine, o-tolidine, 2,6-dichlorobenzaldehyde and other dyestuffs intermediates, in which 4-chloro-2-nitrotoluene is a pharmaceutical raw material and o-toluidine is the raw material of pesticide fungicides and spices. O-nitrotoluene is a pharmaceutical raw material to prepare 2,2'-dinitrobenzene, o-nitrobenzyl bromide, bromine alkane and other medicines, and is also the raw material to prepare indole to be used as amino acids and plant growth regulators. O-nitrotoluene is the raw material to prepare dinitrotoluene to be used as powder. O-toluidine can also be used as vulcanization accelerator and to prepare o-nitrobenzoic acid as pharmaceutical raw material.
Chemical Properties
Yellow flammable liquid; insoluble in water; soluble in chloroform and benzene; immiscible with ethanol and ethyl ether.
Application
2-Nitrotoluene is a nitroaromatic compound. It is mainly used in the production of o-toluidine, o-tolidine, and also used as the important raw materials of dyes, paints, plastics and pharmaceutical. In the pharmaceutical industry, it is used for the production of nifedipine, tegretol, imipramine hydrochloride, bromide has hydrochloride amine and sodium dicloxaeillin.
Production method
Nitrify toluene with mixed acid to generate mixed nitrotoluene, which mainly consists of o-nitrotoluene (about two-thirds) and p-nitrotoluene (about one-third). The mixed nitrotoluene can be separated to get the pure product. Add toluene to the reactor and cool to below 25℃. Then add the mixed acid (ie, 25-30% of nitric acid, 55-58% of sulfuric acid and 20-21% of water) and control the temperature not exceeding 50℃. Stir for 1-2h, and then stand for 6h. Separate the generated nitrotoluene, and wash them with water and alkali liquor to remove unreacted toluene and aliphatic compound. The crude nitrotoluene products consist of 55-60% of o-nitrotoluene, 2-5% of m-nitrotoluene and 35-40% of p-nitrotoluene, with a yield of 90-95%. The various isomers can be separated by crude distillation and crystallization according to the difference of the boiling point and melting point. Namely, first distill the crude nitrotoluene under vacuum to separate out the majority of o-nitrotoluene. And then the residual fraction containing more p-nitrotoluene is separated by vacuum distillation, and cooled for crystallization and separated to obtain the finished products. The tarry substance with high boiling point remains in the still. M-nitrotoluene remains in the mother liquor separated out the p-nitrotoluene, and can be obtained by rectification after repeated accumulation. The purity of ortho and para nitrotoluene can respectively reach 98% and 99%. The domestic process is the two-pot series process, and the reaction temperature of the main pot is 40-45℃ and the second pot is 50-55℃. The preparation of mixed acid is roughly similar, including 26-28% of nitric acid, 56-57% of sulfuric acid and 16-18% of water. The raw material consumption quota: toluene (98%) 800kg/t, nitric acid (98%) 470kg/t, sulfuric acid (92.5%) 450kg/t, caustic soda (42%) 100kg /t
Description
2-Nitrotoluene is a light yellow to darker yellow-green liquid. It is used for the synthesis of a variety of industrial products. These include to synthesise agricultural and rubber chemicals, azo and sulphur dyes, and dyes for cotton, wool, silk, leather, and paper. O-nitrotoluene decomposes on contact with strong oxidants, reducing agents, acids, or bases producing toxic fumes, nitrogen oxides, and carbon monoxide.
Chemical Properties
Nitrotoluene is formed in 3 isomeric forms.
The o-and m-forms are yellow liquids or solids. The p-form
is a pale yellow crystalline solid. All have weak aromatic
odors. The Odor Thresholds are: 0.05 mg/L (o-isomer);
1.74 ppm (m-isomer).
Physical properties
Clear, colorless to pale yellowish combustible liquid with a faint, aromatic odor. May darken on
exposure to air.
Uses
2-Nitrotoluene is used as an intermediate for the o-toludine synthesis, which finds application in the dyestuff industry. It is employed as a reagent in detecting and photometric determining oxidizing agent. It is also used in the determination of prussic acid content in the air. It acts as a precursor to prepare 2-amino-4-chlorotoluene, 2-amino-6-chlorotoluene, nitrotoluenesulfonic acids and toluene nitrosulfonic chlorides. It acts as a nitrogen supplement in the culture medium of pseudomonas sp. strain ClS1. It acts as a carbon and energy supplement in the culture medium of Pseudomonas sp. strain JS42.
Definition
ChEBI: 2-nitrotoluene is a mononitrotoluene that is toluene carrying a nitro substituent at position 2. It has a role as an environmental contaminant and a carcinogenic agent.
Preparation
2-Nitrotoluene was synthesized by nitration of toluene with mixed acid, A mixture of mononitrotoluene isomers can be prepared from the nitration of toluene between -10 oC and 30 oC. Lower temperatures result in little or no reaction, while higher temperatures will result in double nitration forming dinitrotoluenes.
Application
2-Nitrotoluene is a taggant used in explosive compounds and is often used as a simulant for nitro-based high explosives. Its photodissociation leads to the formation of atomic carbon and its emission is observed to overlap with NO emission. The energy transfer from laser-excited nitrogen to NO leads to a long lifetime of NO emission. Argon atoms stabilise the 2-nitrotoluene molecule and delay its photodissociation.
[1]
General Description
Light yellow oily liquid with a characteristic odor of aromatic nitro compounds. Sinks in water. Derived from toluene by nitration and separation by fractional distillation. Flash point 223°F.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
2-Nitrotoluene is toxic by inhalation, ingestion and skin aborption, targeting the blood, central nervous system, skin, and gastrointestinal tract. Symptoms include, anoxia, weakness or dizziness, nausea and vomiting. If 2-Nitrotoluene contacts the eye, the eye should be irrigated immediately. If 2-Nitrotoluene contacts the skin, the area should be washed with soap. If inhaled, respiratory support should be administered. Finally, if ingested, medical attention should be sought. 2-Nitrotoluene also reacts with sulfuric acid, sodium hydroxide, hydrogen, sodium, tetranitromethane, reducing agents and strong oxidizers. 2-Nitrotoluene is very heat sensitive.
Hazard
Toxic by inhalation, ingestion, skin absorption. Methemoglobinemia. Probable carcinogen.
Health Hazard
INHALATION, INGESTION, OR SKIN: Headache, flushing of face, dizziness, dyspnea (difficult breathing), cyanosis, nausea, vomiting, muscular weakness, increased pulse and respiratory rate, irritability, and convulsions. SKIN: Irritation.
Safety Profile
Confirmed carcinogen.
A poison. Moderately toxic by ingestion.
Mucous membrane effects by inhalation.
Mutation data reported. Combustible when
exposed to heat or open flame. To fight fire,
use water spray, fog, foam, CO2. Potentially
explosive reaction with alkali (e.g., sodmm
hydroxide). When heated to decomposition
it emits toxic fumes of NOx. See also other
methylnitrobenzene entries and NITRO
COMPOUNDS OF AROMATIC
HYDROCARBONS.
Potential Exposure
The nitrotoluenes are used in the
production of toluidines and other dye intermediates.
All isomers are used in manufacture of agriculture and
rubber chemicals and in various dyes.
Carcinogenicity
o-Nitrotoluene is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals and supporting data on mechanisms of carcinogenesis.
Environmental Fate
Biological. Robertson et al. (1992) reported that toluene dioxygenases from Pseudomonas
putida F1 and Pseudomonas sp. Strain JS 150 oxidized the methyl group forming 2-nitrobenzyl
alcohol.
Shipping
UN1664 Nitrotoluenes, (o-; m-; p-), Hazard
Class: 6.1; Labels: 6.1-Poisonous materials.
Purification Methods
Crystallise 2-nitrotoluene (repeatedly) from absolute EtOH by cooling in a Dry-ice/alcohol mixture. Further purify it by passing an alcoholic solution through a column of alumina. [Beilstein 5 IV 845.]
Incompatibilities
Decomposes on contact with strong oxidizers;
strong acids; reducing agents; strong bases; ammonia,
amines producing toxic fumes, causing fire and explosion
hazard. Heat above 190C may cause explosive decomposition.
Attacks some plastics, rubbers, and coatings.
Waste Disposal
Controlled incineration-care
must be taken to maintain complete combustion at all
times. Incineration of large quantities may require scrubbers
to control the emission of nitrogen oxides.
References
[1] H. DIEZ-Y RIEGA; H. E. UV and 532 nm Photo-Dissociation of 2-Nitrotoluene: Observation of Electronically-Excited NO; Emission from Carbon (I); N2–NO Energy Transfer; and Stabilization of 2-Nitrotoluene-Ar Clusters[J]. Applied Physics B, 2012, 108 1: 189-196. DOI:10.1007/s00340-012-5087-5.
