Question

What happens when – (write chemical equations only)

(i) Mixture of calcium acetate and calcium formate is dry distilled?

(ii) Acetone is distilled with conc. H₂SO₄?

(iii) Acetone is heated with chloroform in presence of alkali?

(iv) Formic acid is heated with Fehling’s solution?

(v) Formaldehyde is heated with conc. NaOH solution?

OR

(b) Explain the following:

(i) Benzoin condensation

(ii) Perkin’s reaction

(iii) Cross Cannizzaro reaction

Hint:

Dry distillation of salts, aldol condensation, and haloform reactions follow unique mechanistic pathways.

Answer 1

(b) What happens when – (write chemical equations only)

(i) Mixture of calcium acetate and calcium formate is dry distilled?

(COO)_2Ca + HCOO_2Ca → CH_3CHO + CaCO_3

(ii) Acetone is distilled with conc. H₂SO₄?

2 CH_3COCH_3 → CH_3CH=CH_2 + CH_3COOH

(iii) Acetone is heated with chloroform in presence of alkali?

CH_3COCH_3 + CHCl_3 + NaOH → CH_3CCl_3OH + NaCl

(iv) Formic acid is heated with Fehling’s solution?

HCOOH + 2Cu²⁺ + 5OH^- → CO_2 + Cu_2O + 3H_2O

(v) Formaldehyde is heated with conc. NaOH solution?

HCHO + NaOH → HCOONa + H_2

OR

(b) Explain the following:

(i) Benzoin condensation

Solution:

Step 1: In benzoin condensation, two aldehyde molecules condense in presence of cyanide ion.

Step 2: Reaction:

2 C_6H_5CHO + CN^- → C_6H_5CH(OH)C(=O)C_6H_5

Benzoin is formed.

(ii) Perkin’s reaction

Solution:

Step 1: Perkin’s reaction involves condensation of aromatic aldehydes with acid anhydrides.

Step 2: Reaction:

C_6H_5CHO + (CH_3CO)_2O → C_6H_5CH=CHCOOH

It forms cinnamic acid.

(iii) Cross Cannizzaro reaction

Solution:

Step 1: Cross Cannizzaro reaction occurs between two different aldehydes, one undergoing oxidation and the other reduction.

Step 2: Example:

HCHO + C_6H_5CHO + NaOH → HCOONa + C_6H_5CH_2OH