Iodotoluenes are

aryl iodide In organic chemistry, an aryl halide (also known as a haloarene) is an aromatic compound in which one or more hydrogen atoms directly bonded to an aromatic ring are replaced by a halide ion (such as fluorine F''−'', chlorine Cl−1,−3,−5, bro ...

s based on

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon with the chemical formula , often abbreviated as , where Ph stands for the phenyl group. It is a colorless, water Water is an inorganic compound with the c ...

in which at least one aromatic hydrogen atom is replaced with an

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

atom. They have the general formula C₇H_8–''n''I_''n'', where ''n'' = 1–5 is the number of iodine atoms.

Monoiodotoluene

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.

Benzyl iodide Benzyl iodide is an organic compound with the chemical formula . The compound consists of a benzene ring with an attached iodidemethyl group. The substance is an alkyl halide and is a constitutional isomer of the iodotoluenes. Synthesis Benzyl i ...

is an isomer, which has an iodine substituted for one of the hydrogens of

's methyl group, and it is sometimes named α-bromoiodine.

Preparation

A laboratory route to ''o''- and ''p''-iodotoluene proceeds from

, which is treated with a mixture of iodine and nitric acid in an

electrophilic aromatic substitution Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic ring, aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitut ...

. The resulting mixture of ''o'' and ''p''-iodotoluene is then separated by

fractional freezing Fractional freezing is a process used in process engineering and chemistry to separate substances with different melting points. It can be done by partial melting of a solid, for example in zone refining of silicon or metals A metal ( ...

; 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.

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 Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, which dissolves in water as K+ and ions to give an intensely pink to purple solution. Potassium permanganate is widely us ...

to form 2-iodobenzoic acid and 4-iodobenzoic acid, respectively.

References

{{reflist Iodobenzene derivatives Toluenes Multiple compounds, tabular

Monoiodotoluene

Properties

Preparation

Uses

See also

References