Give one chemical test to distinguish between the following pairs of compounds .
i. Methylamine and dimethylamine
ii. Secondary and tertiary amines
iii. Ethylamine and aniline
iv. Aniline and benzylamine
v. Aniline and N-methylaniline

Explanation

i. These can be distinguished by the carblamine test . Methlamine is a primary amine , wih an alcoholic sloution fo ` KOH` and ` CHCl_3` it gives an offensive smell of methyl isocyanide. In contrast , diethylamine is a secondary amine and hence does not gvive this test .
` (##KSV_CHM_ORG_P2_C15_E01_023_S01.png" width="80%">
`underset((2^(@)amine))underset("Diethylamine")((CH_(3)CH_(2))_(2)NH) overset(CHCI_(3)//KOH(alc.))underset(Delta)rarr` No reaction ii. These can be distinguished by Liebermann nitroamine test , since `2^@` amines give Liebermann nitroamine test while ` 3^@` amines doe not ` 2^@` amines on treatement with ` HNO_2` (generated in situ by the action of ` HCl` on ` NaNO_2)` gives yellow colured oily N-nitrosamine . For example .

N-Nitrosodiethylamine on warming with a crystal of phenol and conecntrated `H_2SO_4` gives a green solution which when made alkaline with aqueous ` NaOH` trurns deep blue and then red on dilution.
iii. `EtNH_2` is `1^@` aliphatic amine and aniline is `1^@` aliphatic amine and aniline is `1^@` aromatic amine . they can be distinguished by azo dye test .
` EtNbH_2 + HNO_2 rarr EtOH +N_2 + H_2O`
` ArNH_2 + HNO_2 rarr ArN_2 Cl overset(beta-"Naphthol")underset(overset(Theta)(OH))rarr` Azo dye
iv . Aniline and benzylamine : Benzyamine is `1^@` aliphatic amine and aniline is `1^@` areomatic amine . Same distiction as in (iii) above .
v. a. Aniline and N-methylaniline:
aniline is `1^@` aromatic amine , gives arbylamine test , whereas N-methyl aniline is `2^@` aromatic amine and does not give carbylmine test but gives
b. Aniline gives azo dye test but N-methylamiline does not.
c. They can be separated by Hinsverg`s reactiong test .