{{Short description|Group of ortho, meta, para isomers}} {{Distinguish|Benzyl chloride}} '''Chlorotoluenes''' are aryl chlorides based on toluene in which at least one aromatic hydrogen atom is replaced with a chlorine atom. They have the general formula C<sub>7</sub>H<sub>8–''n''</sub>Cl<sub>''n''</sub>, where ''n'' = 1–5 is the number of chlorine atoms.

==Monochlorotoluene==

Monochlorotoluenes are chlorotoluenes containing one chlorine atom. There are three isomers, each with the formula C<sub>7</sub>H<sub>7</sub>Cl.

=== Properties === The isomers differ in the location of the chlorine, but have the same chemical formula. All have very similar boiling points, although ''p''-chlorotoluene has a much higher melting point due to a more tightly packed crystal structure.

<!-- Here is a table of data; skip past it to edit the text. --> {| align="center" border="1" cellspacing="0" cellpadding="3" style="margin: 0 0 0 0.5em; background: #FFFFFF; border-collapse: collapse; border-color: #C0C090;"

! {{Chemical datatable header}} align="center" colspan="4" | Monochlorotoluene isomers |- | Common name | {{no redirect|2-Chlorotoluene|'''''o''-chlorotoluene'''}} | {{no redirect|3-Chlorotoluene|'''''m''-chlorotoluene'''}} | {{no redirect|4-Chlorotoluene|'''''p''-chlorotoluene'''}} |- | Structure | align="center" | 90px | align="center" | 90px | align="center" | 55px |- | Systematic name | 1-chloro-2-methylbenzene | 1-chloro-3-methylbenzene | 1-chloro-4-methylbenzene |- | Molecular formula | align="center" colspan="3" | C<sub>7</sub>H<sub>7</sub>Cl (C<sub>6</sub>H<sub>4</sub>ClCH<sub>3</sub>) |- | Molar mass | align="center" colspan="3" | 126.586 g/mol |- | Appearance | align="center" colspan="3" | colorless liquid |- | CAS number | [95-49-8] | [108-41-8] | [106-43-4] |- ! {{Chemical datatable header}} align="center" colspan="5" | Properties |- | Density and phase | 1.073 g/ml, liquid | 1.072 g/ml, liquid | 1.069 g/ml, liquid |- | Solubility in water | align="center" colspan="3" | practically insoluble |- | Other solubilities | align="center" colspan="4" | Soluble in non-polar solvents such as aromatic hydrocarbons |- | Melting point | −35&nbsp;°C (−31&nbsp;°F; 238 K) | −47&nbsp;°C (−52.6&nbsp;°F; 226 K) | 7&nbsp;°C (44.6&nbsp;°F; 280 K) |- | Boiling point | 159&nbsp;°C (318.2&nbsp;°F; 432 K) | 162&nbsp;°C (323.6&nbsp;°F; 435 K) | 162&nbsp;°C (323.6&nbsp;°F; 435 K) |- |Magnetic susceptibility | −81.98·10<sup>−6</sup> cm<sup>3</sup>/mol | −80.07·10<sup>−6</sup> cm<sup>3</sup>/mol | −80.07·10<sup>−6</sup> cm<sup>3</sup>/mol |}

Benzyl chloride is an isomer, which has a chlorine substituted for one of the hydrogens of toluene's methyl group, and it is sometimes named α-chlorotoluene.

==Preparation== A laboratory route to 2- and 4-chlorotoluene proceeds from 2- and 4-toluidines (i.e. 2- and 4-aminotoluene). These compounds are diazotized followed by treatment with cuprous chloride.<ref>{{cite journal |doi=10.15227/orgsyn.003.0033|title=o-Chlorotoluene and p-Chlorotoluene|journal=Organic Syntheses|year=1923|volume=3|page=33|author=C. S. Marvel and S. M. McElvain}}</ref> 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.<ref name=Ullmann>{{Ullmann |doi=10.1002/14356007.o06_o03|title=Chlorinated Benzenes and Other Nucleus-Chlorinated Aromatic Hydrocarbons|year=2011|last1= Beck|first1=Uwe|last2=Löser|first2=Eckhard|isbn=978-3527306732}}</ref>

==Uses== 2- and 4-chlorotoluene are precursors to the corresponding benzyl chloride (ClC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>Cl), benzaldehyde (ClC<sub>6</sub>H<sub>4</sub>CHO), and benzoyl chloride (ClC<sub>6</sub>H<sub>4</sub>C(O)Cl).<ref name=Ullmann/> 2- and 4-chlorotoluenes are converted to 2-chlorobenzonitrile and 4-chlorobenzonitrile, respectively.<ref>{{Ullmann|doi=10.1002/14356007.a17_363|title=Nitriles|year =2000|last1=Pollak|first1=Peter|last2=Romeder|first2=Gérard|last3=Hagedorn|first3=Ferdinand|last4=Gelbke|first4=Heinz-Peter|isbn=3527306730}}</ref> Chlorotoluenes are precursors to dichlorotoluenes.

==See also== *Bromotoluene *Iodotoluene

==References== {{Reflist}} * [https://www.cdc.gov/niosh/npg/npgd0135.html CDC - NIOSH Pocket Guide to Chemical Hazards - o-Chlorotoluene]

Category:Chlorobenzene derivatives Category:Toluenes Category:Multiple compounds, tabular