MolSynapsequestion bank

MolSynapse / Question bank / Organic Reaction Mechanisms II: Electrophilic and Radical Reactions / Hydroboration, oxymercuration, halohydrin formation

NEET levelSingle correct optionDifficulty 1 of 3o2169

Which statement about the hydroboration step of an alkene with $BH X_{3} \cdot THF$ is correct?

AIt is a free radical chain reaction needing peroxide
BIt proceeds by anti addition through a cyclic bromonium-type ion
C $B - H$ adds across the $C = C$ in one concerted step with both atoms adding to the same face and no carbocation formed
DIt proceeds through a free carbocation and obeys Markovnikov's rule

Answer: C

Hydroboration goes through a four-centre transition state. B and H add to the same face (syn addition) in one step. No carbocation forms, so there is no rearrangement.

Practice Organic Reaction Mechanisms II: Electrophilic and Radical Reactions More on Hydroboration, oxymercuration, halohydrin formation

Previous questionNext question

More questions on Hydroboration, oxymercuration, halohydrin formation

The major product of propene on treatment with BH3.THF followed by H2O2/NaOH is NEET level
Oxymercuration-demercuration (Hg(OAc)2, H2O then NaBH4) of but-1-ene gives mainly NEET level
Ethene reacts with Br2 in water to give mainly NEET level
Which reagent sequence converts 2-methylpropene into 2-methylpropan-1-ol? NEET level
Cyclohexene reacts with Br2 in water. The major product is NEET level
1-Methylcyclohexene is treated with Hg(OAc)2, H2O and then NaBH4. The major product is JEE Main level