How do you convert the following:

(i) Benzoic acid to Benzaldehyde

(ii) Ethyne to Ethanal

(iii) Acetic acid to Methane

OR

Write the equations involved in the following reactions:

(i) Stephen reaction

(ii) Wolff-Kishner reaction

(iii) Etard reaction

(i) Benzoic acid to Benzaldehyde

• Benzoic acid is chlorinated with thinly chloride to obtain Benzoyl chloride.

• Benzoyl chloride is hydrogenated to obtain Benzaldehyde- Rosenmund’s reduction.

(ii) Ethyne to Ethanal

On treating alkynes with H₂SO₄ and HgSO₄ , a molecule of water is added to form aldehydes.

(iii) Acetic acid to methane

• Acetic acid is first converted to its sodium salt.

• Sodium salt of acetic acid is heated with sodium hydroxide & calcium oxide to form methane. In this process a molecule of CO₂ is lost.

OR

(i) Stephen Reaction

• On treating nitriles with stannous chloride in the presence of HCl, it is reduced to imine.

• Imine when hydrolysed results in aldehydes.

(ii) Wolff Kishner reduction

When a carbonyl compound is treated with hydrazine followed by heating with sodium or potassium hydroxide in boiling solvent like ethylene glycol, it gets reduced to a hydrocarbon. (CO group changes to CH₂ group).

(iii) Etard reaction

On treating Toluene with chromyl chloride, methyl groul is oxidized to a chromium complex which on hydrolysis results in benzaldehyde.