CBSE 2022 · Region 2 · Set 2 · Q7 · 3 marks
Write the equations involved in the following reactions :(i)Cannizzaro reaction(ii)Aldol condensation(iii)Hell-Volhard-Zelinsky reaction(b)Which acid of each pair would you expect to be stronger ? Give reason.(I)$\displaystyle \mathrm{F}-\mathrm{CH}_{2}-\mathrm{COOH}$ or $\displaystyle \mathrm{Cl}-\mathrm{CH}_{2}-\mathrm{COOH}$(II) or (ii)Distinguish between Propanal and Propanone.
Write the equations involved in the following reactions :
(i)
Cannizzaro reaction
(ii)
Aldol condensation
(iii)
Hell-Volhard-Zelinsky reaction
(b)
Which acid of each pair would you expect to be stronger ? Give reason.
(I)
$\displaystyle \mathrm{F}-\mathrm{CH}_{2}-\mathrm{COOH}$ or $\displaystyle \mathrm{Cl}-\mathrm{CH}_{2}-\mathrm{COOH}$
(II)
or
(ii)
Distinguish between Propanal and Propanone.
Marking-scheme solution
(i)
$\displaystyle 2$ HCHO $\displaystyle \xrightarrow{\text{conc. OH}^-}$ HCOO$\displaystyle ^-$ + CH$\displaystyle _3$OH
(ii)
2CH$\displaystyle _3$CHO $\displaystyle \xrightarrow{\text{dil. NaOH}}$ CH$\displaystyle _3$—CH(OH)—CH$\displaystyle _2$—CHO
(iii)
CH$\displaystyle _3$—COOH $\displaystyle \xrightarrow[\text{H}_2\text{O}]{\text{Cl}_2/\text{P}}$ CH$\displaystyle _2$(Cl)—COOH
(i)
(I)
F-CH$\displaystyle _2$COOH, due to -I effect of F.
(II)
p-nitrobenzoic acid, due to -I effect of NO$\displaystyle _2$ group.
(ii)
Heat both the compounds with NaOH and I$\displaystyle _2$, propanone gives yellow ppt. of iodoform while propanal does not.
Aldehydes, Ketones and Carboxylic AcidsChemical Reactions of Aldehydes, Ketones and Carboxylic AcidsApplyshort_answermedium
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CBSE Class 12 Chemistry past-paper question from the 2022board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.