Ch.8 - Reactions of Alkenes

Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook

Wade 9th Edition

Ch.8 - Reactions of Alkenes

Problem 27a

Chapter 8, Problem 27a

Predict the carbenoid addition products of the following reactions.
(a) cyclohexene + CHCl₃, 50% NaOH/H₂O

Verified step by step guidance

Identify the reaction type: This is a carbenoid addition reaction, where a carbene or carbenoid intermediate is generated and reacts with the alkene to form a cyclopropane ring.

Understand the reagents: CHCl₃ (chloroform) in the presence of a strong base like NaOH generates a dichlorocarbene (:CCl₂) intermediate. This occurs via deprotonation of CHCl₃ by NaOH, followed by elimination of a chloride ion.

Generate the dichlorocarbene intermediate: The reaction mechanism involves the following steps: (1) NaOH deprotonates CHCl₃ to form the trichloromethyl anion (CCl₃⁻), and (2) CCl₃⁻ eliminates a chloride ion (Cl⁻) to form the neutral dichlorocarbene (:CCl₂).

React the dichlorocarbene with cyclohexene: The alkene (cyclohexene) reacts with the dichlorocarbene (:CCl₂) in a concerted mechanism to form a cyclopropane ring. The two π-electrons of the alkene bond with the carbene carbon, resulting in a three-membered ring structure.

Draw the product: The final product is a cyclopropane ring fused to the cyclohexane ring, with two chlorine atoms attached to the cyclopropane carbon. The product can be represented as 7,7-dichlorobicyclo[4.1.0]heptane.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

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

Carbenoids

Carbenoids are reactive intermediates that resemble carbenes but are stabilized by adjacent groups. They can participate in various reactions, including additions to alkenes. In the context of the given reaction, the carbenoid generated from CHCl3 in the presence of a strong base like NaOH can add to the double bond of cyclohexene, leading to the formation of a halogenated product.

Electrophilic Addition Reactions

Electrophilic addition reactions involve the addition of an electrophile to a nucleophilic site, typically a double bond in alkenes. In this case, the carbenoid acts as an electrophile that adds to the cyclohexene, resulting in the formation of a more stable product. Understanding the mechanism of electrophilic addition is crucial for predicting the outcome of the reaction.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the reaction of cyclohexene with the carbenoid, the regioselectivity will determine which carbon atom of the double bond the electrophile adds to, influencing the final product's structure. Analyzing the stability of potential products helps predict the major outcome.

Recommended video:

Guided course

05:09

Heck Reaction

Related Practice

Textbook Question

The chiral BINAP ligand shown in Figure 8-8 contains no asymmetric carbon atoms. Explain how this ligand is chiral.

1305

views

Textbook Question

One of the principal components of lemongrass oil is limonene, C₁₀H₁₆. When limonene is treated with excess hydrogen and a platinum catalyst, the product is an alkane of formula C₁₀H₂₀. What can you conclude about the structure of limonene?

1291

views

Textbook Question

What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction?

656

views

Textbook Question

Predict the carbenoid addition products of the following reactions.

(c)

1706

views

rank