Question

How is the following transformation best carried out?

(A) $B{{H}_{3}}-THF; {{H}_{2}}O/NaOH$
(B) ${{O}_{3}}; Zn/AcOH$
(C) $HgS{{O}_{4}}/{{H}_{2}}S{{O}_{4}}/{{H}_{2}}O$
(D) $Os{{O}_{4}}; NaHS{{O}_{3}}$

Answer 1

Hint: To carry out the transformation, we need to check each reagent mentioned in the option.

Complete step by step answer:
(A) Hydroboration-
This is the process where a hydrogen boron bond is added to the double bond. Bond can be either carbon-carbon bond or carbon-nitrogen bond. This can be also performed on a carbon-carbon triple bond.

Hydroboration of terminal di-alkyne produces enols by anti-Markovnikov’s addition rule which rearrange to produce di-aldehyde at ends.

(B) Ozonolysis- It is an organic redox reaction. It refers to the organic chemical reaction where ozone cleaves the unsaturated bonds. Bonds can be of alkenes, alkynes, or azo compounds (compounds with diazinyl functional group).

Ozonolysis produces dicarboxylic acids and $C{{O}_{2}}$ by oxidative cleavage.

(C) Oxymercuration- It is an electrophilic addition organic reaction that transforms an alkene into neutral alcohol.

Oxymercuration also produces enol by Markovnikov’s addition rule which rearranges to form di-ketone product.

(D) Alkynes do not react with $Os{{O}_{4}}$.

Hence, we can see that oxymercuration gives the best transformation.
So, the correct answer is “Option C”.

Note: Do note that all the three mechanisms explained which shows reaction with alkynes have the end product as alcohol at some point. But the given transformation can only be carried out by oxymercuration.