/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q 29P When the following stereoisomer ... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 7: Q 29P (page 369)

When the following stereoisomer of 2-bromo-1,3-dimethylcyclohexane is treated with sodium methoxide, no E2 reaction is observed. Explain why this compound cannot undergo the E2 reaction in the chair conformation.

Short Answer

Expert verified

E2 elimination is not possible here as E2 elimination requires hydrogen and anti-coplanar; and in a chair conformation of cyclohexane, this requires that the two groups be trans-diaxial. There are no hydrogen trans-diaxial to bromine in the chair conformation of this reaction, thus E2 is not possible.

Step by step solution

01

Step by step solution:  Step 1: E2 elimination

E2 elimination is a one-step mechanism, and base is a part of rate-determining step. The reaction rate is proportional to the concentrations of both eliminating agent and the substrate. E2 elimination requires the beta-hydrogen and leaving group, halogento be anti-coplanar with each other, so that elimination reaction can occur effectively, and double bond can be formed.

02

Reason for why a stereoisomer of 2-bromo-1,3-dimethylcyclohexane does not give E2 reaction

E2 elimination is not possible here as it requires hydrogen and anti-coplanar; and in a chair conformation of cyclohexane, this requires that the two groups be trans-diaxial. There are no hydrogen trans diaxial to bromine in the chair conformation of this reaction, thus E2 is not possible.

Chair conformation of particular stereoisomer of 2-bromo-1,3-dimethylcyclohexane

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A double bond in a six-membered ring is usually more stable in an endocyclic position than in an exocyclic position. Hydrogenation data on two pairs of compounds follow. One pair suggests that the energy difference between endocyclic and exocyclic double bonds is about

9 KJ/mol. The other pair suggests an energy difference of about

5 KJ/mol. Which number do you trust as being more representative of the actual energy difference? Explain you answer.

Propose mechanisms and draw reaction-energy diagrams for the following reactions. Pay particular attention to the structures of any transition states and intermediates. Compare the reaction-energy diagrams for the two reactions and explain the differences.

  1. 2-Bromo-2-methylbutane reacts with sodium methoxide in methanol to give 2-methylbut-2-ene (among other products).
  2. 2-Bromo-2-methylbutane reacts in boiling methanol to give 2-methylbut-2-ene (among other products).

Show how you would convert (in one or two steps) 1-phenylpropane to the three products shown below. In each case, explain what unwanted reactions might produce undesirable impurities in the product.

When 2-bromo-3-phenylbutane is treated with sodium methoxide, two alkenes result (by E2 elimination). The Zaitsev product predominates.

  1. Draw the reaction, showing the major and minor products.
  2. When one pure stereoisomer of 2-bromo-3-phenylbutane reacts, one pure stereoisomer of the major product results. For example, when (2R,3R)-2-bromo-3-phenylbutane reacts, the product is the stereoisomer with the methyl group cis. Use your models to draw a Newmanprojection of the transition state to show why this stereospecificity is observed.
  3. Use a Newman projection of the transition state to predict the major product of elimination of (2S,3R)-2-bromo-3-phenylbutane.
  4. Predict the major product from elimination of (2S,3S)-2-bromo-3-phenylbutane. This prediction can be made without drawing any structures, by considering the results in part (b).

Propose mechanisms to account for the observed products in the following reactions. In some cases, more products are formed, but you only need to account for the ones shown here.
See all solutions

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Read Explanation

The Earths Atmosphere

Read Explanation

Chemistry Branches

Read Explanation

Inorganic Chemistry

Read Explanation

Kinetics

Read Explanation

Making Measurements

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.