Textbook Question
Predict the major product(s) of the following allylic bromination reactions.
(d)
11. Radical Reactions
Allylic Bromination
2:40 minutesProblem 31b
Textbook Question
What is the major product of the following reactions? Disregard stereoisomers:
b. 
Verified step by step guidance1
Step 1: Recognize the reagents and conditions. NBS (N-Bromosuccinimide) is used for allylic or benzylic bromination in the presence of a radical initiator, such as peroxide and heat.
Step 2: Identify the allylic position in the molecule. The allylic position is the carbon atom adjacent to the double bond in the cyclopentene structure.
Step 3: Understand the mechanism. The reaction proceeds via a radical mechanism. Peroxide and heat generate radicals, which abstract a hydrogen atom from the allylic position, forming an allylic radical.
Step 4: Bromine from NBS reacts with the allylic radical to form the major product. The bromine atom attaches to the allylic position, resulting in an allylic bromide.
Step 5: Consider resonance stabilization. The allylic radical is resonance-stabilized, so bromination can occur at either of the two equivalent allylic positions. Disregard stereoisomers as instructed.
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2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reaction Mechanisms
Understanding reaction mechanisms is crucial in organic chemistry as they describe the step-by-step process by which reactants transform into products. This includes identifying intermediates, transition states, and the movement of electrons. Familiarity with mechanisms helps predict the major products of reactions based on the stability of intermediates and the energy changes involved.
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Regioselectivity
Regioselectivity refers to the preference of a chemical reaction to occur at one location over another in a molecule. This concept is essential for predicting the major product of a reaction, as certain pathways may lead to more stable or favorable products. Understanding regioselectivity helps in determining which isomer will be formed when multiple possibilities exist.
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