Question

How is carboxylic acid prepared from cumene?

Answer 1

Hint: We must know the reagents used for the conversion to the given product. Cumene is used in the preparation of phenol. So, phenol can be converted into carboxylic acid with the help of oxidizing agents.

Complete step by step answer:
Cumene process is very well known for the synthesis of phenol. So we will first make phenol and will precede the reaction. It is an industrial process for synthesis of phenol using benzene and isopropyl benzene. These both ingredients are very cheap and hence are fit for industrial manufacturing. The two reactants upon oxidation forms phenol and acetone. The reaction is as follow
\[{{\text{C}}_6}{{\text{H}}_6} + {\text{C}}{{\text{H}}_3} - {\text{CH}} = {\text{C}}{{\text{H}}_2} \to {{\text{C}}_6}{{\text{H}}_5} - {\text{OH}} + {\text{C}}{{\text{H}}_3} - {\text{CO}} - {\text{C}}{{\text{H}}_3}\]
Now we will convert phenol to carboxylic acid. Zinc dust can be used to reduce alcohol to benzene followed by Friedal craft alkylation using methyl chloride and aluminium chloride. Then toluene will form and we will oxidize the toluene using strong oxidizing agents such as potassium permanganate in acidic conditions to form benzoic acid, benzoic acid is carboxylic acid. Hence, we have used the cumeme process and derived the carboxylic acid. The reactions are as follow:
\[{{\text{C}}_6}{{\text{H}}_5}{\text{OH}}\xrightarrow[\Delta ]{{{\text{Zn dust}}}}{{\text{C}}_6}{{\text{H}}_6}\xrightarrow[{{\text{AlC}}{{\text{l}}_3}}]{{{\text{C}}{{\text{H}}_3}{\text{Cl}}}}{{\text{C}}_6}{{\text{H}}_5}{\text{C}}{{\text{H}}_3}\xrightarrow{{{\text{KMn}}{{\text{O}}_4}/{{\text{H}}_2}{\text{S}}{{\text{O}}_4}}}{{\text{C}}_6}{{\text{H}}_5}C{\text{OOH}}\]
The cumene process was invented in 1942 by R. Udris and P. Sergeyev. Cumene is basically isopropyl benzene. It is an intermediate that formed during the reaction mechanism of conversion from benzene to phenol.

Note:
Cumene is aromatic hydrocarbon having an aliphatic substitution. It is colourless and is flammable just like other hydrocarbons. It is one of the constituents of crude oil and has a sharp odor. It is soluble in inorganic solvent such as ether, acetone and ethanol.