(a) (i)
‌CH3C≡N+‌ DIBAL-H ‌+H2O→CH3‌CHO +NH2‌OH+H+→CH3‌CH=N−OH +H2O
A-Acetaldehyde
B-Acetaloxide
(ii) The IUPAC name is 3-bromobenzaldehyde.
(iii) Phenol and Benzoic Acid can be distinguished by iron chloride (FeCl3) test. As phenol gives violet colouration with neutral FeCl3 solution while benzoic acid gives buff coloured precipitate of ferric benzoate.
‌6C6H5‌OH+FeCl3→[Fe(OC6H5)6]3−+3H+
‌‌Violet complex ‌+3‌HCl
‌3C6H5‌COOH+FeCl3→(C6H5‌COO)3‌Fe+3‌HCl Violet complex +3‌HCl

3C6H5‌COOH

Benzoic‌acid

+FeCl3→

(C6H5‌COO)3‌Fe

Buff‌coloured‌ppt.

+3‌HCl
OR
(b) (i) Benzoic acid to benzaldehyde - Firstly benzoic acid is converted into benzoyl chloride by adding sulphonyl chloride and then by Rosenmund reduction reaction using Pd−BaSO4 converted into benzaldehyde.

(ii) Propan-1-ol to 2-bromo propanoic acid -Firstly propanol is converted into propanoic acid by oxidizing in presence of alk. KMnO4 and then by using Red Phosphorous/ NaOH and Bromine gas is further converted into 2-Bromo-propanoic acid

CH3−CH2−CH2−OH

Propanol

‌ alkaline ‌KMnO4

──────▸

CH3−CH2− O ∥ C −OH

Propanoic‌acid

+Br2‌

‌ red P ‌ ──────▸

NaOH

CH3− CH | Br −COOH

2−Bromopropanoic‌acid

(iii) Ethanal or Acetaldehyde into But-2-en-1-al Aldol condensation (in presence of dil NaOH ) followed by dehydration.

2CH3‌CHO

Ethanal

‌ dil NaOH‌

─────▸

CH3− OH | CH −CH2−CHO

Acetaldehyde

‌

Δ

────▸

−H2O

CH3−CH=CH−CHO

But−2−en−1−al