Question

Show how you would accomplish the following synthetic conversions.

(a)But-1-ene -> butan-1-ol

(b)But-1-ene ->butan-2-ol

(c)2-bromo-2,4-dimethylpentane ->2,4-dimethylpentan-3-ol

Short answer

(a)

(b)

(c)

Step-by-step solution

Hydroboration-oxidation

Hydroboration-oxidation is the reaction in which alkenes get converted to alcohols via two-step process,namely hydroboration and oxidation. In this reaction, from borane gets added to the less substituted carbon of alkene in the hydroboration step and then in the oxidation step, the hydroxyl group from hydrogen peroxide gets added to the same carbon where is attached. This reaction is an example of anti-markovnikov addition in which the hydroxyl group gets attached to the carbon which is less hindered or less substituted.

Reaction a

Oxymercuration-demercuration

But-1-ene undergoes oxymercuration-demercuration reaction in which an alkene is treated with mercury(II)acetate,followed by treatment with sodium borohydride, . This reaction is an example of markovnikov addition in which the hydroxyl group gets attached to the more substituted carbon. Thus, the product is butan-2-ol.

Reaction b

Reaction with KOH

2-bromo-2,4-dimethylpentane undergoes reaction with potassium hydroxide followed by heating, which is dehydrohalogenation reaction, and the resulting product is the formation of an alkene which then undergoes hydroboration-oxidation in which the addition of boron and hydroxyl group occurs on the less substituted carbon and the final product formed is 2,4-dimethyl-pentan-3-ol.

Reaction c