2-Nitrotoluene is a light yellow toxic liquid. It is readily soluble in toluene, benzene, diethyl ether, chloroform, acetone and many other organic solvents. Solubility in water is about 0.0652% wt at 30°C. In a solid state 2-nitrotoluene exists in two crystal modifications. α-Modification is stable, β-one is metastable.
Methyl group in o-nitrotoluene can be oxidized by the action of potassium permanganate KMnO4, manganese(IV) oxide MnO2 or potassium dichromate K2Cr2O7 in acidic medium as well as by potassium hexacyanoferrate(III) K3[Fe(CN)6] in alkali medium resulting in o-nitrobenzoic acid. Electrochemical oxidation of 2-nitrotoluene in acetic or sulfuric acid leads to o-nitrobenzaldehyde formation.
Being boiled with KOH solution 2-nitrotoluene disproportionates to form anthranylic (2-aminobenzoic) acid:
Like almost aromatic nitrocompounds 2-nitrotoluene is easily reduced with hydrogen in statu nascendi (e.g. by action of metal zinc in hydrochloric acid) to form o-toluidine (2-aminotoluene):
Direct chlorination of o-nitrotoluene occurs mainly on the radical path and leads to side chain chlorinated adduct 2-chloromethyl nitrobenzene
. In addition partial substitution of nitro- group with chlorine atom takes place in this reaction.
Treatment of 2-nitrotoluene with the mixture of concentrated nitric and sulfuric acids results in formation of 2,4- and 2,6-dinitroderivatives.
o-Nitrotoluene is quite toxic compound. It can be absorbed into the body by inhalation of its vapour or through the skin. It is able to oxidize haemoglobin of blood into hemiglobin and cause anaemia. It ia also dangerous to central nervous system and causes liver and kidney disorders.
Industrially 2-nitrotoluene is manufactured by toluene nitration. This reaction is not selective and results in the mixture of isomers. There are two processes which mostly used for 2-nitrotoluene preparation:
- Liquid phase nitration. Toluene is nitrated with the mixture of 55-66% of sulfuric acid, 28-32% of nitric acid and 12-20% of water in continuous process. Reaction mixture is stirred intensively at the temperature 35-40°C. Nitration occurs in the phase interface. End product consists of 2-nitro, 3-nitro and 4-nitro isomers with the ratio 55-60%, 3-4% and 35-40% respectively. 4-Nitrotoluene is separated from the mixture by freezing, then the mixture is distilled at low pressure to isolate 2-nitrotoluene from 3-nitrotoluene.
- Gaseous phase nitration. Toluene is nitrated with nitric acid at 100-140°C in the presence of catalyst (5% solution of sulfuric acid applied on silica gel or aluminum oxide). The toluene conversion is about 61%. The ratio of 2-nitrotoluene and 4-nitro isomer is 1:1.85
- as an intermediate for o-toluidine production. o-Toluidine is widely used in dyestuff industry;
- as a reagent in detecting and photometric determining oxidizing agents (such as molecular chlorine, NO3-, NO2-, Cu(III), Cu(II), Cr(VI), Au(III));
- as a test for determining prussic acid HCN concentration in air;
- as a parent compound in nitrotoluenesulfonic acids and toluene nitrosulfonic chlorides syntheses;
- as an intermediate in herbicides and rubbers production;