Question

The reagent(s) used in hydroboration oxidation of propene are:
(A) B\(_2\)H\(_6\)
(B) H\(_2\)O
(C) H\(_2\)O\(_2\)
(D) OH\(^-\)

• A. (A), (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D)
• D. (B), (C) and (D) only

Hint:

Hydroboration-oxidation is a useful reaction for the anti-Markovnikov addition of water to alkenes. The reaction proceeds with syn addition to form an alcohol.

Answer 1

The Correct Option is B

The hydroboration-oxidation reaction is an organic reaction that does not follow the Markovnikov's rule. This reaction is used to convert alkenes into alcohols using a two-step process:

1. Hydroboration: In the first step, the alkene reacts with diborane (B₂H₆) to add hydrogen (H) and boron (BH₂) across the double bond.
2. Oxidation: In the second step, the resulting organoborane is oxidized using hydrogen peroxide (H₂O₂) in the presence of a base, typically hydroxide ion (OH^-), to form an alcohol.

Let's consider the reagents involved in both steps of the mechanism:

• Diborane (B₂H₆): This reagent is essential for the hydroboration step.
• Water (H₂O): While not directly involved in the mechanism as a separate reagent, water provides the medium for the reaction and facilitates the oxidation step.
• Hydrogen Peroxide (H₂O₂): This reagent is crucial for the oxidation step to convert organoboranes to alcohols.
• Hydroxide ion (OH^-): This base is used to promote the oxidation process, though not always listed explicitly as an independent reagent.

In summary, for the hydroboration-oxidation of propene, the key reagents required are diborane, water, and hydrogen peroxide. Although OH^- assists in the mechanism, the main reagents focused in exams are typically B₂H₆, H₂O, and H₂O₂.

Thus, the correct answer is:

• (A), (B), and (C) only