Addition Reactions of Alkenes | Dihalides, Halohydrins & Hydroboration–Oxidation (Syn/Anti Addition)

Описание: Addition Reactions of Alkenes | Dihalides, Halohydrins & Hydroboration–Oxidation (Syn/Anti Addition)
In this organic chemistry lecture, we explore addition reactions of alkenes with a strong mechanistic focus on stereochemistry and regiochemistry. The video explains how the π bond of an alkene is transformed into two new σ bonds, converting sp² carbons into sp³ carbons through different electrophilic addition pathways.

We begin with the halogenation of alkenes (Br₂, Cl₂) and show how the reaction proceeds through a cyclic halonium ion intermediate, leading to the anti addition of halogens and the formation of vicinal dihalides. The stereochemical consequences of the cyclic intermediate are emphasized with clear reaction diagrams.

Next, we discuss halohydrin formation, where alkenes react with halogens in the presence of water. This reaction also proceeds via a halonium ion, followed by nucleophilic attack by water, resulting in anti addition and Markovnikov orientation of the OH group.

The lecture then covers hydroboration–oxidation, including the use of 9-BBN, highlighting its syn addition, anti-Markovnikov regioselectivity, and the concerted nature of the mechanism. We explain why boron adds to the less substituted carbon and how oxidation replaces boron with OH while retaining stereochemistry.

Throughout the lecture, you will learn:

Cyclic halonium ion intermediates

Anti vs syn addition in alkene reactions

Markovnikov vs anti-Markovnikov orientation

Stereochemical outcomes of dihalide and halohydrin formation

Mechanistic details of hydroboration–oxidation

Keywords
addition reactions of alkenes, alkene halogenation, dihalide formation, halonium ion mechanism, halohydrin formation, anti addition, syn addition, hydroboration oxidation, 9 BBN reaction, anti Markovnikov addition, alkene stereochemistry, organic chemistry alkenes, electrophilic addition reactions

This video is ideal for undergraduate organic chemistry students, pre-med and pre-pharmacy learners, and anyone preparing for exam problem solving in alkene chemistry.

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