4-Bromophenylacetic acid

4-Bromophenylacetic acid, also known as p-bromophenylacetic acid, is an organic compound. It is a derivative of phenylacetic acid containing a bromine atom in the para position.

Preparation
4-Bromophenylacetic acid may be prepared by the addition of a bromine atom to phenylacetic acid through electrophilic aromatic substitution. It was first prepared in the laboratory by treatment of phenylacetic acid with bromine and mercuric oxide; a mixture of the 2- and 4- isomers is made, and the 4- isomer is isolated by fractional crystallization.

It can also be made by condensing 4-bromobenzyl bromide with sodium cyanide in ethanol, and then hydrolyzing the nitrile with sodium hydroxide.

Reactions
Methyl 4-bromophenylacetate is made from 4-bromophenylacetic acid by Fischer esterification, refluxing it with methanol acidified with sulfuric acid. An ethyl ester can be made in an analogous way using ethanol instead of methanol.

A hydrazone derivative, 2-(4-bromophenyl)acetohydrazide, is made by refluxing the methyl ester with hydrazine. Further hydrazone derivatives of 4-bromophenylacetic acid are made by condensing the simple hydrazone with aldehydes, forming a double bond with the second nitrogen. At least 19 of these hydrazones are known.

4-Bromophenylacetic acid is a chemical that can be purchased.

Plant protoplasts conjugate aspartic acid with 4-bromophenylacetic acid to form 4-bromophenylacetyl- L -aspartic acid.

4-Bromophenylacetic acid reacts with sodium tetraphenylborate to form felbinac which can be further converted to xenbucin.

Properties
The ionic conductance has been measured.