Question

Which of the following produces 2-hexanone?
(i)1-Hexyne is treated with $ {{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}} $ , $ {\text{HgS}}{{\text{O}}_{\text{4}}} $ , and water.
(ii)3-Methyl-2-heptene is treated with $ {{\text{O}}_{\text{3}}} $ followed by hydrolysis.
(iii)n-butyl magnesium bromide reacts with acetaldehyde followed by hydrolysis and then chromic acid oxidation.
(iv)Hydroboration oxidation of 1-Hexyne.
(A) (i), (ii), and (iii)
(B) (i) and (ii) only
(C) (i) and (iii) only
(D) (i), (ii), and (iv)
(E) All the four methods

Answer 1

Hint: There are different methods of production of ketones and those include either reduction of the carboxylic groups or oxidation of alcohols and triple bonds. Hydroboration oxidation reaction gives alcohol.

Complete step by step answer:
In this reaction an $ {\text{OH}} $ is added to the triple bonds between the carbon atoms which is then reduced to a double bond and this leads to the formation of an enol. This enol form tautomerizes to the more stable keto form.
When any 3-Methyl-2-heptene is treated with $ {{\text{O}}_{\text{3}}} $ followed by hydrolysis, the carbon-carbon double bond is hydrolysed into two parts and an oxygen atom gets placed on each resulting to the formation of two ketones.
n-butyl magnesium bromide reacts with acetaldehyde followed by hydrolysis to form 2- hexanol by Grignard reaction and then chromic acid oxidation results in the formation of 2-hexanone.
Hydroboration oxidation of 1-Hexyne results in the formation of hexan-1-al.
Hence, the correct answer is option A.

Note:
When any alkane is treated with mercuric sulphate under acidic conditions, then it is hydrolysed into the keto group. Here the mercurous ion acts as the catalyst that accepts the electron pair from the carbon-carbon triple bond resulting in the formation of a tri-membered cycle which is strained and quickly dissociates in the presence of the water molecules resulting in the formation of the ketone.