CBSE 2022 · Region 2 · Set 1 · Q10 · 3 marks
Write the equation involved in the following reactions:(i)Rosenmund reduction(ii)Etard reaction(iii)Stephen reaction(b)Which acid of each pair would you expect to be stronger? Give reason.(I)$\displaystyle CH_3COOH$ or $\displaystyle F–CH_2–COOH$(II) or $\displaystyle CH_3–COOH$(ii)Distinguish between Pentan-$\displaystyle 2$-one and Pentan-$\displaystyle 3$-one.
Write the equation involved in the following reactions:
(i)
Rosenmund reduction
(ii)
Etard reaction
(iii)
Stephen reaction
(b)
Which acid of each pair would you expect to be stronger? Give reason.
(I)
$\displaystyle CH_3COOH$ or $\displaystyle F–CH_2–COOH$
(II)
or $\displaystyle CH_3–COOH$
(ii)
Distinguish between Pentan-$\displaystyle 2$-one and Pentan-$\displaystyle 3$-one.
Marking-scheme solution
(i)
RCOCl + H$\displaystyle _2$ $\displaystyle \xrightarrow{\text{Pd} \cdot \text{BaSO}_4}$ RCHO + HCl
(ii)
$\displaystyle + \mathrm{CrO_2Cl_2}$ $\displaystyle \xrightarrow{\mathrm{CS_2}}$ $\displaystyle \xrightarrow[\Delta]{\mathrm{H_3O^+}}$
(iii)
R—CN $\displaystyle \xrightarrow{\text{SnCl}_2 + \text{HCl}}$ RCH=NH $\displaystyle \xrightarrow{\text{H}_3\text{O}^+}$ RCHO + NH$\displaystyle _3$
(i)
(I)
F-CH$\displaystyle _2$COOH, due to -I effect of F.
(II)
CH$\displaystyle _3$COOH, acetate ion is more resonance stabilised than phenoxide ion.
(ii)
Heat both the compounds with NaOH and I$\displaystyle _2$, pentan-$\displaystyle 2$-one gives yellow ppt. of iodoform while pentan-$\displaystyle 3$-one does not.
Aldehydes, Ketones and Carboxylic AcidsChemical Reactions of Aldehydes, Ketones and Carboxylic AcidsRemembershort_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.