The Use of Bromobenzene as a Solvent

Bromobenzene is the simplest member of the class of bromobenzenes, that is benzene in which a single hydrogen has been substituted by a bromine. A liquid at room temperature (m.p. -30℃; b.p.760 156℃), it is a member of bromobenzenes, a bromoarene and a volatile organic compound.

Polarity

In order to detect polarity in aryl compounds, we have to check the electronegativity values of different atoms attached with the aryl ring. For carbon (C), the electronegativity value is 2.55, and for bromine (Br), it is 2.96. The EN differences is very small, therefore, we generally think that bromobenzene is a non-polar molecule.

Solvent

Bromobenzene is used as a solvent, particularly for large-scale crystallisations, and for the introduction of phenyl groups in organic synthesis. It has a role as a non-polar solvent, a hepatotoxic agent and a mouse metabolite.

The bromination of bromobenzene in polar solvent at different temperatures was investigated by H. Tian et al.^[1]. The polarity of the solvent was adjusted by adding ionic liquid. The results showed that, the amount of p-dibromobenzene would be increased as rasing polarity of the solvent, on the contray, the amount of o-dibromobenzene would be increased. The maximum yield of 92.02% of p-dibromobenzene could be obtained in CH2Cl2 containing 2(wt)% ionic liquid. 

Reference

[1] Bromination selectivity of bromobenzene in polar solvents containing ionic liquid. Chemistry Bulletin 77(4):375-377.