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Ch. 9 - Alkenes II: Oxidation and Reduction
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 8, Problem 9

(••) Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (iii) Br₂, H₂O(h)

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1
Identify the type of reaction: The reaction of an alkene with Br₂ in the presence of H₂O is a halohydrin formation reaction.
Understand the mechanism: The reaction proceeds via the formation of a bromonium ion intermediate, which is then attacked by water.
Determine regioselectivity: The water molecule will attack the more substituted carbon of the bromonium ion, leading to Markovnikov addition.
Consider stereochemistry: The addition of Br and OH will be anti, meaning they will add to opposite sides of the double bond.
Predict the product: The final product will be a halohydrin, with a bromine atom and a hydroxyl group added across the double bond.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electrophilic Addition

Electrophilic addition is a fundamental reaction mechanism in organic chemistry where an electrophile reacts with a nucleophile, typically involving alkenes. In the case of alkenes reacting with Br₂, the double bond acts as a nucleophile, attacking the electrophilic bromine molecule, leading to the formation of a cyclic bromonium ion intermediate.
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Bromohydrin Formation

Bromohydrin formation occurs when an alkene reacts with bromine in the presence of water. The bromonium ion intermediate is attacked by water, leading to the formation of a bromohydrin, which is a compound containing both a bromine atom and a hydroxyl group (-OH) on adjacent carbon atoms, resulting in a vicinal dibromide.
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Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In the reaction of alkenes with Br₂ and H₂O, the regioselectivity is influenced by the stability of the carbocation intermediates formed during the reaction, often leading to the more substituted alcohol being produced as the major product.
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