Question

An organic compound (X) having molecular formula C$_5$H$_10$O can show various properties depending on its structures. Draw each of the structures if it:
(I) shows Cannizzaro reaction.
(II) reduces Tollens' reagent and has a chiral carbon.
(III) gives positive iodoform test.

Hint:

For organic reactions, remember the reagents involved in reductions or oxidations like in Clemenssen and Etard reactions.

Answer 1

(I) For the Cannizzaro reaction, the compound must be non-enolizable aldehyde (without alpha-hydrogens). In this case, the compound undergoes disproportionation in the presence of a strong base, forming one alcohol and one carboxylic acid.
(II) A compound that reduces Tollens' reagent is an aldehyde. If it has a chiral carbon, it is asymmetric and can show optical activity.
(III) The positive iodoform test indicates the presence of a methyl ketone group (-COCH$_3$) or a structure that can undergo oxidation to form such a group.
(ii) Write the reaction involved in the following: 
(I) Clemenssen reduction. 
(II) Etard reaction. 
(I) Clemenssen reduction involves the reduction of carbonyl compounds to hydrocarbons using zinc amalgam (Zn/Hg) and hydrochloric acid (HCl). 
\[ \text{Aldehyde or Ketone} + \text{Zn/Hg} \longrightarrow \text{Alkane} \] 
(II) Etard reaction involves the oxidation of methyl groups attached to aromatic rings to an aldehyde in the presence of chromium-based reagents. 
\[ \text{Toluene} + \text{CrO}_2\text{Cl}_2 \longrightarrow \text{Benzaldehyde} \]