(A), (B) and (C) are three non-cyclic functional isomers of a carbonyl compound with molecular formula C₄H₈O. Isomers (A) and (C) give a positive Tollens' test whereas (B) does not, but (B) gives a positive iodoform test. (A) and (B) on reduction with Zn(Hg)/conc. HCl give the same product (D).
(a) Write the structures of (A), (B), (C) and (D).
(b) Out of (A), (B) and (C), which one is least reactive towards addition of HCN?
(a) Write the structures of (A), (B), (C) and (D).
(b) Out of (A), (B) and (C), which one is least reactive towards addition of HCN?
Solution
Tollens-positive A, C = the two aldehydes of CHO: butanal and 2-methylpropanal.
B = the ketone, butan-2-one (iodoform-positive, CHCO–).
Clemmensen of A (butanal) and of B (butanan-2-one) both give \textbf{n-butane} = D — so A is the straight-chain butanal, C the branched 2-methylpropanal.
(a) A: CHCHCHCHO; B: CHCOCHCH; C: (CH)CHCHO; D: CHCHCHCH.
(b) Ketones are least reactive to nucleophilic addition → \textbf{B}.
B = the ketone, butan-2-one (iodoform-positive, CHCO–).
Clemmensen of A (butanal) and of B (butanan-2-one) both give \textbf{n-butane} = D — so A is the straight-chain butanal, C the branched 2-methylpropanal.
(a) A: CHCHCHCHO; B: CHCOCHCH; C: (CH)CHCHO; D: CHCHCHCH.
(b) Ketones are least reactive to nucleophilic addition → \textbf{B}.
CBSE Class 12 Board · 2018 · Subjective