CBSE Class 12 Chemistry Notes: Carboxylic Acids – Important Questions for Boards

Prob 1. Write chemical reactions to effect the following transformation.

            (a)  Butan-1-ol to butanoic acid

            (b)  Benzyl alcohol to phenylacetic acid

            (c)  Bromobenzene to benzoic acid

            (d)  p-methylacetophenone to benzene-1, 4-dicarboxylic acid

Sol.

a.

b.

c.

d.

Prob 2. Arrange the following compounds in increasing order of their boiling points:

            acetic acid, methyl formate, acetamide, propan-1-ol

Sol.      (i)  Out of all these compounds methyl formate does not undergo H-bonding therefore, its boiling point is the lowest.

(ii)   Amongst the remaining three compounds intramolecular H-bonding is most extensive in acetamide, followed by acetic acid and least in propan-1-ol. Therefore, their boiling points decrease in the same order i.e. acetamide > acetic acid > propan-1-ol. Thus, the overall increasing order of their boiling points is methyl formate < propan-1-ol
< acetic acid < acetamide.

Prob 3.

Sol.

Prob 4. A dicarboxylic acid (A), C₄H₆O₄, gave a compound (B), C₆H₁₀O₄ upon treatment with excess of methanol and a trace of H₂SO₄. Subsequent treatment of (B) with LiAlH₄ followed by usual work up gave C, C₄H₁₀­O₂. Heating of A yielded D, C₄H₄O₃. Assign structures to A, B, C and D. 

Sol.

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