Mustard oil test for distinguishing between primary aliphatic and primary aromatic amines?
No, aromatic primary amines cannot be distinguished from aliphatic amines using mustard oil test as it reacts with carbon disulfide to give phenylisothiocyanate.

Aniline is reacted with carbon disulfide in the presence of mercury chloride to give the isothiocyanate. The reaction is given in this site.

$$\ce{C6H5NH2 + S=C=S -&gt;[HgCl2] C6H5NCS + HgS + 2HCl}$$.

Aliphatic amines also give the same products,  isothiocyanate, mercuric sulfide and hydrochloric acid and as such this test cannot be used to distinguish between aliphatic amines and aromatic amines.



Alternatively, it is also formed in the presence of ammonium hydroxide and lead nitrate.