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Chlorotoluene

From Wikipedia, the free encyclopedia

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

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Monochlorotoluenes are chlorotoluenes containing one chlorine atom. There are three isomers, each with the formula C7H7Cl.

Properties

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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

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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

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

See also

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References

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  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. ^ a b 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. ^ 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.