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Ch. 12 - Radicals
Bruice - Organic Chemistry 8th Edition
Bruice8th EditionOrganic ChemistryISBN: 9780135213711Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoBruice 8th EditionCh. 12 - RadicalsProblema 46c
Capitolo 12, Problema 46c

Draw the products of the following reactions, including all stereoisomers:
c.

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1
Identify the type of reaction: The presence of NBS (N-bromosuccinimide) and peroxide indicates a radical bromination reaction, specifically allylic bromination.
Recognize the allylic position: In the given alkene, the allylic position is the carbon adjacent to the double bond. This is where the bromine will be added.
Initiate the radical mechanism: Peroxide initiates the formation of bromine radicals. The heat (Δ) helps in the homolytic cleavage of the peroxide bond, generating radicals.
Form the allylic radical: The bromine radical abstracts a hydrogen from the allylic position, forming an allylic radical. This radical is stabilized by resonance.
Add bromine to the allylic radical: The bromine radical reacts with the allylic radical, forming the allylic bromide. Consider all possible resonance structures to identify all stereoisomers.

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NBS (N-Bromosuccinimide)

NBS is a reagent commonly used in organic chemistry for bromination reactions, particularly in allylic and benzylic positions. It provides a source of bromine in a controlled manner, allowing for selective substitution reactions. The presence of NBS in the reaction facilitates the formation of radical intermediates, which are crucial for the subsequent steps in the reaction mechanism.
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Radical Mechanism

The radical mechanism involves the formation of free radicals, which are highly reactive species with unpaired electrons. In the context of the reaction with NBS, the radical mechanism typically proceeds through initiation, propagation, and termination steps. This mechanism is essential for understanding how bromine is added to the allylic position of the alkene, leading to the formation of various products, including stereoisomers.
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Stereoisomerism

Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity but differ in the spatial arrangement of atoms. In reactions involving alkenes and radicals, stereoisomers can arise due to the formation of chiral centers or the presence of double bonds. Understanding stereoisomerism is crucial for predicting the different products formed in the reaction, including cis/trans or E/Z isomers.
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Determining when molecules are stereoisomers.
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At 600 °C, the ratio of the relative rates of formation of a tertiary, a secondary, and a primary radical by a chlorine radical is 2.6 : 2.1 : 1. Explain the change in the degree of regioselectivity compared to what was found in Problem 44.

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Using the given starting material and any necessary organic or inorganic reagents, indicate how the desired compounds could be synthesized:

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Draw the products of the following reactions, including all stereoisomers:

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Draw the products of the following reactions, including all stereoisomers:

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Draw the products of the following reactions, including all stereoisomers:

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Domanda del libro di testo

A chemist wanted to determine experimentally the relative ease of removing a hydrogen atom from a tertiary, a secondary, and a primary carbon by a chlorine radical. He allowed 2-methylbutane to undergo chlorination at 300 °C and obtained as products 36% 1-chloro-2-methylbutane, 18% 2-chloro-2-methylbutane, 28% 2-chloro-3-methylbutane, and 18% 1-chloro-3-methylbutane. What values did he obtain for the relative ease of removing a hydrogen atom from tertiary, secondary, and primary hydrogen carbons by a chlorine radical under the conditions of his experiment?

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