Textbook Question
Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (ii) Cl2
(d)
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10. Addition Reactions
Halogenation
2:39 minutesProblem 45k(ii)
Textbook Question
Predict the product(s) that would result when the alkenes are allowed to react under the following conditions: (ii) Cl2
(k) 
Verified step by step guidance1
Identify the type of reaction: The reaction involves an alkene and Cl₂, which is a halogenation reaction. In this reaction, the π-bond of the alkene reacts with Cl₂ to form a vicinal dihalide (two chlorine atoms added to adjacent carbons).
Understand the mechanism: The reaction proceeds via an electrophilic addition mechanism. The π-electrons of the alkene attack one of the chlorine atoms, forming a cyclic chloronium ion intermediate.
Determine the regioselectivity and stereochemistry: The cyclic chloronium ion intermediate is opened by the attack of the chloride ion (Cl⁻) on the more substituted carbon, leading to anti-addition (the two chlorine atoms will be added on opposite sides of the double bond).
Draw the product(s): Replace the double bond in the alkene with single bonds, and add one chlorine atom to each of the two carbons that were part of the double bond. Ensure the stereochemistry reflects anti-addition.
Verify the product(s): Check that the product(s) are vicinal dihalides and that the stereochemistry is consistent with anti-addition. If the alkene is symmetric, there will be one product; if asymmetric, there may be multiple stereoisomers.
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Video duration:
2mKey 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 Cl₂, the double bond acts as a nucleophile, attacking the chlorine molecule, leading to the formation of a cyclic chloronium ion intermediate. This process is crucial for understanding how alkenes can undergo transformations to form more complex products.
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Stereochemistry
Stereochemistry refers to the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. When alkenes react with Cl₂, the addition can lead to the formation of stereoisomers, such as enantiomers or diastereomers, depending on the configuration of the resulting product. Understanding stereochemistry is essential for predicting the specific products formed during the reaction.
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Halogenation of Alkenes
Halogenation of alkenes is a specific type of electrophilic addition reaction where halogens, such as chlorine or bromine, add across the double bond of an alkene. This reaction typically results in the formation of vicinal dihalides, where two halogen atoms are added to adjacent carbon atoms. Recognizing the mechanism and outcome of halogenation is vital for predicting the products when alkenes react with Cl₂.
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