Iodotoluenes are aryl iodides based on toluene in which at least one aromatic hydrogen atom is replaced with an iodine atom. They have the general formula C7H8–nIn, where n = 1–5 is the number of iodine atoms.

Monoiodotoluene

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p-Iodotoluene sample

Monoiodotoluenes are iodotoluenes containing one iodine atom. There are three isomers, each with the formula C7H7I.

Properties

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The isomers differ in the location of the iodine, but have the same chemical formula.

Monoiodotoluene isomers[1][2][3]
Common name o-iodotoluene m-iodotoluene p-iodotoluene
Structure      
Systematic name 1-iodo-2-methylbenzene 1-iodo-3-methylbenzene 1-iodo-4-methylbenzene
Other names 2-iodotoluene 3-iodotoluene 4-iodotoluene
Molecular formula C7H7I (C6H4ICH3)
Molar mass 218.03 g/mol
Appearance Clear dark brown liquid white to yellow solid
CAS number [615-37-2] [625-95-6] [624-31-7]
Properties
Melting point 35 °C (95 °F; 308 K)[4]
Boiling point 211-212 °C (412-414 °F; 484-485 K)[4] 211.5 °C (412.7 °F; 484.7 K)[5]

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

Preparation

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A laboratory route to o- and p-iodotoluene proceeds from toluene, which is treated with a mixture of iodine and nitric acid in an electrophilic aromatic substitution. The resulting mixture of o and p-iodotoluene is then separated by fractional freezing; cooling the mixture in an ice bath results in solidification of p-iodotoluene, which can then be isolated by filtration, while the o-iodotoluene remains behind as a liquid.[4]

Uses

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Iodotoluenes are precursors to many organic building blocks. For example, the methyl group of o-iodotoluene and p-iodotoluene may be oxidized using potassium permanganate to form 2-iodobenzoic acid and 4-iodobenzoic acid, respectively.[6]

See also

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References

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  1. ^ "2-Iodotoluene". PubChem. National Center for Biotechnology Information. Retrieved January 19, 2023.
  2. ^ "3-Iodotoluene". PubChem. National Center for Biotechnology Information. Retrieved January 19, 2023.
  3. ^ "4-Iodotoluene". PubChem. National Center for Biotechnology Information. Retrieved January 19, 2023.
  4. ^ a b c Datta, Rasik Lal; Chatterjee, Nihar Ranjan (1917). "Halogenation. Xv. Direct Iodination of Hydrocarbons by Means of Iodine and Nitric Acid". Journal of the American Chemical Society. 39 (3): 435–441. doi:10.1021/ja02248a012.
  5. ^ "4-Iodotoluene". Sigma Aldrich. Retrieved January 31, 2023.
  6. ^ Varma, P. S.; Panickerp, P. B. (1928). "Influence of substitution on the oxidation of side chains in the benzene nucleus". Proc. 15th Indian Sci. Cong.