Iodotoluene

Not to be confused with Benzyl iodide.

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 C₇H_8–nI_n, where n = 1–5 is the number of iodine atoms.

Monoiodotoluene

p-Iodotoluene sample

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

Properties

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

Monoiodotoluene isomers[1][2][3]
Common name	o-iodotoluene2-Iodotoluene	m-iodotoluene3-Iodotoluene	p-iodotoluene4-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 an iodine substituted for one of the hydrogens of toluene's methyl group, and it is sometimes named α-bromoiodine.

Preparation

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

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

• Chlorotoluene
• Bromotoluene