Write down functional isomers of a carbonyl compound with molecular formula $\mathrm{C}_3 \mathrm{H}_6 \mathrm{O}$. Which isomer will react faster with HCN and why? Explain the mechanism of the reaction also. Will the reaction lead to the completion with the conversion of whole reactant into product at reaction conditions? If a strong acid is added to the reaction mixture what will be the effect on concentration of the product and why?
$$\begin{aligned} &\text { Functional isomers of } \mathrm{C}_3 \mathrm{H}_6 \mathrm{O} \text { containing carbonyl group are }\\ &\underset{\text { Propanal }}{\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO}} \text { and } \underset{\text { Propanone }}{\mathrm{CH}_3 \mathrm{COCH}_3} \end{aligned}$$
(a) Propanal, $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO}$ will react faster with HCN because there is less steric hindrance and electronic factors, which increases its electrophilicity.
(b) The reaction mechanism is as follow
The reaction does not lead to completion because it is a reversible reaction. Equilibrium is established.
(c) If a strong acid is added to the reaction mixture, the reaction is inhibited because production of $\overline{\mathrm{C}} \mathrm{N~ions}$ prevented.
When liquid ' $A$ ' is treated with a freshly prepared ammoniacal silver nitrate solution it gives bright silver mirror. The liquid forms a white crystalline solid on treatment with sodium hydrogen sulphite. Liquid ${ }^{\mathrm{B}}$ ' also forms a white crystalline solid with sodium hydrogen sulphite but it does not give test with ammoniacal silver nitrate. Which of the two liquids is aldehyde? Write the chemical equations of these reactions also.
Since the liquid A reduces ammoniacal silver nitrate, (Tollen's reagent), it 'A' is aldehyde.
