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Chemistry · 2025 · 5 marks
Aldehydes, Ketones and Carboxylic AcidsChemical Reactions of Aldehydes, Ketones and Carboxylic Acids5 marksApplylong answer
CBSE 2025 · Region 1 · Set 1 · Q33
(A) (a) Carry out the following conversions: ( 2 + 3 = 5 ) (i) Ethanal to But-2-enal (ii) Propanoic acid to ethane (b) An alkene A with molecular…
(A)(a)
Carry out the following conversions : $\displaystyle (\mathbf{2}+\mathbf{3}=\mathbf{5})$
(i)
Ethanal to But-$\displaystyle 2$-enal
(ii)
Propanoic acid to ethane
(b)
An alkene A with molecular formula $\displaystyle \mathrm{C}_{5} \mathrm{H}_{10}$ on ozonolysis gives a mixture of two compounds B and C . Compound B gives positive Fehling test and also reacts with iodine and NaOH solution. Compound C does not give Fehling solution test but forms iodoform. Identify the compounds $\displaystyle \mathrm{A}, \mathrm{B}$ and C .
OR 33. (B) An organic compound (A) (molecular formula $\displaystyle \mathrm{C}_{8} \mathrm{H}_{16} \mathrm{O}_{2}$ ) was hydrolysed with dilute sulphuric acid to get a carboxylic acid (B) and an alcohol (C). Oxidation of (C) with chromic acid produced (B). (C) on dehydration gives But-l-ene. Identify (A), (B) and (C) and write chemical equations for the reactions involved.
Marking-scheme solution
(A)(a)
(i)
(ii)
(b)
A = (CH3)2CH=CHCH3 / $\displaystyle 2$-Methylbut-$\displaystyle 2$-ene
B = CH3CHO / Ethanal
C = CH3COCH3/ Acetone/ Propanone
A= C3H7COOC4H9 / Butyl butanoate
B= C3H7COOH / Butanoic acid
C= C4H9OH / Butan-$\displaystyle 1$-ol
C3H7COOC4H9+ dil.H2SO4 → C3H7COOH + C4H9OH
C4H9OH + Conc. Sulphuric acid + Heat→CH3CH2CH=CH2
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