Chlorotoluene

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 C7H8–nCln, 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 C7H7Cl.

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.

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 and phase 1.073 g/ml, liquid 1.072 g/ml, liquid 1.069 g/ml, liquid
Solubility in water practically insoluble
Other solubilities Soluble in non-polar solvents such as aromatic 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 x 10−6 cm3/mol -80.07 x 10−6 cm3/mol -80.07 x 10−6 cm3/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.[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]

Uses

2- and 4-chlorotoluene are precursors to the corresponding benzyl chloride (ClC6H4CH2Cl), benzaldehyde (ClC6H4CHO), and benzoyl chloride (ClC6H4C(O)Cl).[3] 2- and 4-chlorotoluenes are converted to 2-chlorobenzonitrile and 4-chlorobenzonitrile, respectively.[4]

See also
  • Bromotoluene
  • Iodotoluene

References
  1. C. S. Marvel and S. M. McElvain (1923). "o-Chlorotoluene and p-Chlorotoluene". Organic Syntheses. 3: 33. doi:10.15227/orgsyn.003.0033.
  2. Beck, Uwe; Löser, Eckhard (2011). "Chlorinated Benzenes and Other Nucleus-Chlorinated Aromatic Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.o06_o03. ISBN 978-3527306732.
  3. Beck, Uwe; Löser, Eckhard (2011). "Chlorinated Benzenes and Other Nucleus-Chlorinated Aromatic Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.o06_o03. ISBN 978-3527306732.
  4. Pollak, Peter; Romeder, Gérard; Hagedorn, Ferdinand; Gelbke, Heinz-Peter (2000). "Nitriles". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_363. ISBN 3527306730.
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