Question

discuss the chemistry of lassaigne's test

Answer 1

It is a general test for the detection of halogens, nitrogen and sulphur in an organic compound. ... The ionic compounds formed during the fusion are extracted in aqueous solution and can be detected by simple chemical tests. The extract is called sodium fusion extract or Lassaigne's extract.

Answer 2

Acetic acid forms a dimer in benzene solution. ...

This happens with acetic acid dissolved in benzene, but not with acetic acid dissolved in water.

In the aqueous solution, acetic acid will hydrogen bond to water rather than itself, and dimerization does not occur.