Question

Name the reagents used in the following reactions:
(i) ${\text{C}}{{\text{H}}_3} - {\text{CO}} - {\text{C}}{{\text{H}}_3} \to {\left( {{\text{C}}{{\text{H}}_3}} \right)_2} - {\text{CH}} - {\text{OH}}$
(ii) ${{\text{C}}_6}{{\text{H}}_{\text{5}}} - {\text{C}}{{\text{H}}_2} - {\text{C}}{{\text{H}}_3} \to {{\text{C}}_6}{{\text{H}}_{\text{5}}} - {\text{CO}}{{\text{O}}^ - }{{\text{K}}^ + }$

Answer 1

Hint: In the first reaction, ketone is converted to alcohol and thus, it is a reduction reaction. In the second reaction, alkylbenzene is oxidized and thus, it is an oxidation reaction.

Complete step by step answer:
(i) Consider the reaction,
${\text{C}}{{\text{H}}_3} - {\text{CO}} - {\text{C}}{{\text{H}}_3} \to {\left( {{\text{C}}{{\text{H}}_3}} \right)_2} - {\text{CH}} - {\text{OH}}$
In the given reaction, acetone is converted to 2-propanol.
The reaction involves reduction of a ketone to alcohol.
Thus, the reducing agent used to convert acetone to alcohol is sodium borohydride $\left( {{\text{NaB}}{{\text{H}}_{\text{4}}}} \right)$.
Thus, the reagent used in the reaction is ${\text{NaB}}{{\text{H}}_{\text{4}}}$.
Thus,
${\text{C}}{{\text{H}}_3} - {\text{CO}} - {\text{C}}{{\text{H}}_3}\xrightarrow{{{\text{NaB}}{{\text{H}}_{\text{4}}}}}{\left( {{\text{C}}{{\text{H}}_3}} \right)_2} - {\text{CH}} - {\text{OH}}$
(ii) Consider the reaction,
${{\text{C}}_6}{{\text{H}}_{\text{5}}} - {\text{C}}{{\text{H}}_2} - {\text{C}}{{\text{H}}_3} \to {{\text{C}}_6}{{\text{H}}_{\text{5}}} - {\text{CO}}{{\text{O}}^ - }{{\text{K}}^ + }$
In the given reaction, alkylbenzene is converted to its acidic salt.
The reaction involves oxidation of an alkylbenzene.
Thus, the reducing agent used for the oxidation of alkylbenzene is alkaline solution of potassium permanganate $\left( {{\text{KMn}}{{\text{O}}_{\text{4}}} - {\text{KOH}}} \right)$.
Thus, the reagent used in the reaction is ${\text{KMn}}{{\text{O}}_{\text{4}}} - {\text{KOH}}$.
Thus,
${{\text{C}}_6}{{\text{H}}_{\text{5}}} - {\text{C}}{{\text{H}}_2} - {\text{C}}{{\text{H}}_3}\xrightarrow{{{\text{KMn}}{{\text{O}}_{\text{4}}} - {\text{KOH}}}}{{\text{C}}_6}{{\text{H}}_{\text{5}}} - {\text{CO}}{{\text{O}}^ - }{{\text{K}}^ + }$

Note: Sodium borohydride $\left( {{\text{NaB}}{{\text{H}}_{\text{4}}}} \right)$ is white coloured powder in appearance. It does not have any odour i.e. it is odourless. Sodium borohydride is a good reducing reagent for the reduction of aldehydes and ketones to alcohols. It is also used for bleaching of wood pulp, blowing agent for plastics. But sodium borohydride is a mild reducing agent. Thus, for reducing esters to alcohols which is a slow reaction excess of sodium borohydride is required.
Potassium permanganate $\left( {{\text{KMn}}{{\text{O}}_{\text{4}}}} \right)$ is a strong oxidising agent. Thus, it readily accepts electrons from other substances. Alkaline solution of potassium permanganate $\left( {{\text{KMn}}{{\text{O}}_{\text{4}}} - {\text{KOH}}} \right)$ is generally used. It is also used as a mild antiseptic and a drying agent on infected areas of the skin. It is an effective disinfectant to sanitize green leafy vegetables and fruits.