A chemist requires some 3-hexanone for a reaction, but only has some 3-hexene available. Explain using chemical reactions, how the 3-hexene could be converted to 3-hexanone. Include the conditions needed for each step. (You will need two steps).

Answer 1

3-hexene is

CH3CH2CH=CHCH2CH3

which is nice and symmetrical. Thus if we do an addition across the double bond we are not concerned about Markovnikov's rule ((Broken Link Removed)

Similarly as the final product is a ketone any possible chiral centre(s)generated are destroyed, so the chirality of any intermediates is not n issue.

It is thus a matter of choosing reagents and conditions

CH3CH2CH=CHCH2CH3
i) Hg(OAc)2 + Ether + water
ii) NaBH4 + ether + water + NaOH

CH3CH2CH(OH)-CH2CH2CH3
i) Jones reagent

CH3CH2CO-CH2CH2CH3

On a large scale the first step can he done with concentrated sulfuric acid, but the yield is better on a small scale with the mercury reagent.

There are a number of reagents suitable for the oxidation step. Jones reagent is the most suitable. PCC is also a possibility and easy enough to remove the pyridine during the workup of the reaction.