(a) The compound with molecular formula C7H6O forms a 2,4-DNP derivative and reduces Tollen's reagent, so it is an aldehyde. It undergoes Cannizzaro reaction, so the aldehyde group will be directly attached to the benzene ring. On oxidation it gives benzoic acid. So, the compound will be benzaldehyde. The reactions are as follows-
C6H5CHO + 2[Ag(NH3)2]+ + 3OH- → C6H5COO- + 2Ag + 4NH3 + 2H2O
2C6H5CHO conc. NaOH→ C6H5COONa + C6H5CH2OH
(Benzaldehyde) (sodium benzoate) (benzyl alcohol)
C6H5CHO (O)→ C6H5COOH
(b) (i) C6H5OH + FeCl3 → C6H5O-FeCl2
(Phenol) (Violet color complex)
CH3CH2CH2OH + FeCl3 → no reaction
(ii) C6H5COOH + NaHCO3→ C6H5COONa + CO2 + H2O
(benzoic acid) (brisk effervesence)
C6H6 + NaHCO3→ no reaction
(a) A = CH3COOH (oxidation) → acetic acid
B = CH3COCl → acetyl chloride
C= CH3CONH2→ acetamide
D = CH3CONHBr → N- bromoacetamide
(b) Presence of EWG increases the acidity of carboxylic acid by stabilizing the negative charge of conjugate base by –I effect.
Moreover, -I effect of F is greater than that of Cl.
More the no. of EWG, more will be the acidity.
From above points, the increasing order of acidity will be
HCOOH< ClCH2COOH<CCl3COOH< CF3COOH
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