Ch.3 - Structure and Stereochemistry of Alkanes

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

Wade 9th Edition

Ch.3 - Structure and Stereochemistry of Alkanes

Problem 30c

Chapter 3, Problem 30c

Draw the most stable conformation of
c. trans-1-tert-butyl-3-(1,1-dimethylpropyl)cyclohexane.

Verified step by step guidance

Begin by understanding the structure of cyclohexane. Cyclohexane can adopt several conformations, but the chair conformation is the most stable due to minimized steric strain and torsional strain.

Identify the substituents on the cyclohexane ring. In this case, we have a tert-butyl group and a 1,1-dimethylpropyl group. The tert-butyl group is bulky and prefers to be in an equatorial position to minimize steric hindrance.

Since the compound is trans-1-tert-butyl-3-(1,1-dimethylpropyl)cyclohexane, place the tert-butyl group on one carbon in the equatorial position. Then, place the 1,1-dimethylpropyl group on the third carbon in the opposite equatorial position to maintain the trans configuration.

Ensure that the cyclohexane ring is in the chair conformation. This conformation allows both bulky groups to be equatorial, which is the most stable arrangement due to reduced steric interactions.

Double-check the placement of the substituents to confirm that they are trans to each other, meaning they are on opposite sides of the cyclohexane ring. This ensures the correct stereochemistry for the trans configuration.

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Key Concepts

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

Cyclohexane Conformations

Cyclohexane can adopt several conformations, with the chair conformation being the most stable due to minimized steric strain and torsional strain. Understanding the chair conformation is crucial for determining the most stable arrangement of substituents on the cyclohexane ring.

Axial and Equatorial Positions

In the chair conformation of cyclohexane, substituents can occupy axial or equatorial positions. Equatorial positions are generally more stable for bulky groups due to reduced steric hindrance, which is essential for determining the most stable conformation of substituted cyclohexanes.

Trans Configuration

The trans configuration refers to substituents being on opposite sides of the cyclohexane ring. This affects the placement of groups in axial or equatorial positions, influencing the stability of the conformation. Recognizing trans configuration helps in correctly positioning substituents in the most stable conformation.

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Related Practice

Textbook Question

Name the following compounds.

(c)

(d)

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Textbook Question

Use your models to do a chair–chair interconversion on each ring of the conformation of cis-decalin shown in Figure 3-27. Draw the conformation that results.

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Textbook Question

Draw the most stable conformation of

b. trans-1-tert-butyl-2-methylcyclohexane.

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Textbook Question

Draw the most stable conformation of

a. cis-1-tert-butyl-3-ethylcyclohexane.

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Textbook Question

Draw the two chair conformations of each of the following substituted cyclohexanes. In each case, label the more stable conformation.]

c. cis-1-ethyl-4-isopropylcyclohexane