Chlorotoluenes arearyl chlorides based ontoluene in which at least one aromatic hydrogen atom is replaced with achlorine atom. They have the general formula C7H8–nCln, wheren = 1–5 is the number of chlorine atoms.
Monochlorotoluenes are chlorotoluenes containing one chlorine atom. There are three isomers, each with the formula C7H7Cl.
The isomers differ in the location of the chlorine, but have the same chemical formula. All have very similar boiling points, althoughp-chlorotoluene has a much higher melting point due to a more tightly packed crystal structure.
| Monochlorotoluene isomers | ||||
|---|---|---|---|---|
| Common name | o-chlorotoluene | m-chlorotoluene | p-chlorotoluene | |
| Structure |  |  |  | |
| Systematic name | 1-chloro-2-methylbenzene | 1-chloro-3-methylbenzene | 1-chloro-4-methylbenzene | |
| Molecular formula | C7H7Cl (C6H4ClCH3) | |||
| Molar mass | 126.586 g/mol | |||
| Appearance | colorless liquid | |||
| CAS number | [95-49-8] | [108-41-8] | [106-43-4] | |
| Properties | ||||
| Density andphase | 1.073 g/ml, liquid | 1.072 g/ml, liquid | 1.069 g/ml, liquid | |
| Solubility inwater | practically insoluble | |||
| Other solubilities | Soluble in non-polarsolvents such asaromatic hydrocarbons | |||
| Melting point | −35 °C (−31 °F; 238 K) | −47 °C (−52.6 °F; 226 K) | 7 °C (44.6 °F; 280 K) | |
| Boiling point | 159 °C (318.2 °F; 432 K) | 162 °C (323.6 °F; 435 K) | 162 °C (323.6 °F; 435 K) | |
| Magnetic susceptibility | −81.98·10−6 cm3/mol | −80.07·10−6 cm3/mol | −80.07·10−6 cm3/mol | |
Benzyl chloride is an isomer, which has a chlorine substituted for one of the hydrogens oftoluene's methyl group, and it is sometimes named α-chlorotoluene.
A laboratory route to 2- and 4-chlorotoluene proceeds from 2- and 4-toluidines (i.e. 2- and 4-aminotoluene). These compounds arediazotized followed by treatment with cuprous chloride.[1] Industrially, the diazonium method is reserved for 3-chlorotoluene. The industrial route to 2- and 4-chlorotoluene entails direct reaction of toluene with chlorine. The more valuable 4-chlorotoluene is separated from 2-chlorotoluene by distillation. Distillation cannot be applied to separating 3-chlorotoluene from 4-chlorotoluene.[2]
2- and 4-chlorotoluene are precursors to the correspondingbenzyl chloride (ClC6H4CH2Cl),benzaldehyde (ClC6H4CHO), andbenzoyl chloride (ClC6H4C(O)Cl).[2] 2- and 4-chlorotoluenes are converted to2-chlorobenzonitrile and4-chlorobenzonitrile, respectively.[3] Chlorotoluenes are precursors todichlorotoluenes.