Iodotoluene
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[edit]
Monoiodotoluenes are iodotoluenes containing one iodine atom. There are three isomers, each with the formula C7H7I.
Properties[edit]
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[edit]
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[edit]
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[edit]
References[edit]
- ^ "2-Iodotoluene". PubChem. National Center for Biotechnology Information. Retrieved January 19, 2023.
- ^ "3-Iodotoluene". PubChem. National Center for Biotechnology Information. Retrieved January 19, 2023.
- ^ "4-Iodotoluene". PubChem. National Center for Biotechnology Information. Retrieved January 19, 2023.
- ^ 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.
- ^ "4-Iodotoluene". Sigma Aldrich. Retrieved January 31, 2023.
- ^ 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.