Distinguish between :

a. Acetaldehyde and acetone

b. Methanoic acid and Ethanoic acid.

c. Aniline and Ethylamine

a. Acetaldehyde and acetone

Acetaldehyde is an aldehyde with the molecular formula CH3CHO.

Acetone is a ketone with the molecular formula CH3COCH3.

1) Acetaldehyde gives silver mirror with Tollen’s reagent

CH3CHO + 2[Ag (NH3)2] OH → CH3COONH4 + 2Ag + H2O+3NH3

Acetone does not give this test.

2). Acetone undergoes chloroform test forms chloretone.

 (CH3)2CO + CHCl3 → (CH3)2COHCCl3

  Chloretone

But acetaldehyde does not give chloroform test.

b. Methanoic acid and Ethanoic acid.

 Methanoic acid (HCOOH or formic acid)

 Ethanoic acid (CH3COOH or acetic acid)

1) Methanoic acid gives silver mirror test with Tollen’s reagent, whereas ethanoic acid does not give that test.

HCOOH + 2[Ag (NH3)2] OH → 2Ag + 2H2O+CO2+4NH3

(Silver mirror)

2) Methanoic acid gives white precipitate with mercuric chloride solution.

HCOOH +HgCl2→ Hg2Cl2 +CO2 +2HCl

(White ppt)

Ethanoic acid doe not give this test.

c. Aniline and Ethylamine

 Aniline has molecular formula C6H5NH2 and it is an aromatic amine

 Ethylamine has the molecular formula CH3CH2NH2 and is an aliphatic amine

1) Aniline gives positive test for coupling reaction. In which aniline reacts with benzene diazonium chloride in basic medium to give p-aminoazobenzene (dye) which is orange red in colour.

Ethyl amine does not give coupling reaction.

2) Ethyl amine reacts with nitrous acid with release of N2 gas, which can be detected for ethylamine presence.

  0 to 5 C

CH3CH2NH2 + HONO ------------>   C2H5OH + N2 + H2O

Aniline reacts with nitrous acid without release of N2 gas.