Hydrocarbons Ques 4
4. Which one of the following reactions is expected to readily give a hydrocarbon product in good yields ?
[1997]
(a) $\mathrm{RCOOK} \xrightarrow[\text { oxidation }]{\text { Electrolytic }}$
(b) $\mathrm{RCOO}^{-} \mathrm{Ag}^{+} \mathrm{Br}_2$,
(c) $\mathrm{CH}_3 \mathrm{CH}_3 \xrightarrow[\text { hv }]{\mathrm{Cl}_2}$
(d) $\left(\mathrm{CH}_3\right)_3 \mathrm{CCl} \xrightarrow{\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}}$
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Answer:
Correct Answer: 4.(a)
Solution: (a) Electrolysis of a concentrated aqueous solution of either sodium or potassium salts of saturated carboxylic acids yields higher alkane at anode.
Kolbe’s Method
$ 2 \mathrm{RCOOK} \xrightarrow[\text { Oxidation }]{\text { Electrolytic }} \underset{\text { Anode }}{2 \mathrm{RCOO}^{-}}+\underset{\text { Cathode }}{2 \mathrm{~K}^{+}} $
At anode $2 \mathrm{RCOO}^{-} \rightarrow 2 \mathrm{RCOO}+2 \mathrm{e}^{-} \longrightarrow$ $ \mathrm{R}-\mathrm{R}+2 \mathrm{CO}_2 $
$ \begin{aligned} & \text { At Cathode } 2 \mathrm{~K}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{~K} \\ & 2 \mathrm{~K}+\mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{KOH}+\mathrm{H}_2 \uparrow \\ & \end{aligned} $
BETA
