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Reaction scheme of the photobromination of the methyl group of toluene. Photobromination with elemental bromine proceeds analogous to photochlorination also via a radical mechanism. In the presence of oxygen, the hydrogen bromide formed is partly oxidised back to bromine, resulting in an increased yield. Because of the easier dosage of the ...
For example, consider radical bromination of toluene: [5] bromination of toluene with hydrobromic acid and hydrogen peroxide in water. This reaction takes place on water instead of an organic solvent and the bromine is obtained from oxidation of hydrobromic acid with hydrogen peroxide. An incandescent light bulb suffices to radicalize.
o-Toluidine is produced industrially by nitration of toluene to give a mixture of nitrotoluenes, favoring the ortho isomer. This mixture is separated by distillation. 2-Nitrotoluene is hydrogenated to give o-toluidine. [2] The conversion of o-toluidine to the diazonium salt gives access to the 2-bromo, 2-cyano-, and 2-chlorotoluene derivatives.
The general chemical formula of the halogen addition reaction is: C=C + X 2 → X−C−C−X (X represents the halogens bromine or chlorine, and in this case, a solvent could be CH 2 Cl 2 or CCl 4). The product is a vicinal dihalide. This type of reaction is a halogenation and an electrophilic addition.
Nitration of toluene gives mono-, di-, and trinitrotoluene, all of which are widely used. Dinitrotoluene is the precursor to toluene diisocyanate, a precursor to polyurethane foam. Trinitrotoluene (TNT) is an explosive. Complete hydrogenation of toluene gives methylcyclohexane. The reaction requires a high pressure of hydrogen and a catalyst.
The reaction mechanism for chlorination of benzene is the same as bromination of benzene. Iron(III) bromide and iron(III) chloride become inactivated if they react with water, including moisture in the air. Therefore, they are generated by adding iron filings to bromine or chlorine. Here is the mechanism of this reaction:
The nitration of benzene is achieved via the action of the nitronium ion as the electrophile. The sulfonation with fuming sulfuric acid gives benzenesulfonic acid. Aromatic halogenation with bromine, chlorine, or iodine gives the corresponding aryl halides. This reaction is typically catalyzed by the corresponding iron or aluminum trihalide.
The anion reacts with bromine in an α-substitution reaction to give an N-bromoamide. Base abstraction of the remaining amide proton gives a bromoamide anion. The bromoamide anion rearranges as the R group attached to the carbonyl carbon migrates to nitrogen at the same time the bromide ion leaves, giving an isocyanate.