In the following sequence of reactions, the alkene affords the compound ' B ' $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3} \xrightarrow{\mathrm{O}_{3}} \mathrm{~A} \xrightarrow[\mathrm{Zn}]{\mathrm{H}_{2} \mathrm{O}} \mathrm{B}$. The compound B is

(D) $\mathrm{CH}_{3} \mathrm{CHO}$

(A) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHO}$

(B) $\mathrm{CH}_{3} \mathrm{COCH}_{3}$

(C) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COCH}_{3}$

JEE Main · 2008 · 27 Apr 2008 · Offline · Hydrocarbons

In the following sequence of reactions, the alkene affords the compound ' B '

CH_{3} CH = CHCH_{3} O_{3} A H_{2} O Zn B

.
The compound B is

(A) $CH_{3} CH_{2} CHO$
(B) $CH_{3} COCH_{3}$
(C) $CH_{3} CH_{2} COCH_{3}$
(D) $CH_{3} CHO$ ✓ Correct

Answer: (D)

Solution

Ozonolysis cleaves the carbon--carbon double bond of but-2-ene, and reductive work-up with zinc and water delivers carbonyl compounds rather than acids. Because but-2-ene is symmetrical, both carbons of the former double bond carry a methyl and a hydrogen, so each fragment is acetaldehyde and the compound

B

C H_{3} CHO

JEE Main · 2008 · 27 Apr 2008 · Offline · Single correct option

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