Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 6: Problem 142

When ethylene is alkylated by isobutane in the presence of acid, there is obtained not neohexane, \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}_{2} \mathrm{CH}_{3}\), but chiefly 2,3 -dimethylbutane. Account in detail for the formation of this product.

Short Answer

Expert verified
The acid-catalyzed alkylation of ethylene and isobutane primarily forms 2,3-dimethylbutane instead of neohexane due to the stability of intermediates that form during the reaction. Protonation of ethylene creates a secondary carbocation, which is more stable than a primary carbocation. When this carbocation attacks isobutane, another stable carbocation intermediate forms. Finally, deprotonation of this carbocation results in 2,3-dimethylbutane. Overall, the stability of the intermediates favors the formation of 2,3-dimethylbutane.

Step by step solution

01

Isobutane structure

Isobutane, also known as 2-methylpropane, has the chemical formula \(\left(\text{CH}_{3}\right)_{3}\text{CH}\) and the following structure. ``` CH3 | CH3 – C – CH3 ```
02

Ethylene structure

Ethylene, also known as ethene, is an alkene with the chemical formula \(\text{CH}_{2}=\text{CH}_{2}\) and has the following structure. ``` CH2=CH2 ``` #Step 2: Acid-catalyzed reaction between ethylene and isobutane#
03

Protonation of ethylene

When the acid catalyst is introduced, it provides protons that can protonate the alkene (ethylene). Protonation of ethylene forms a carbocation intermediate: ``` CH3 | C+ – CH3 | CH3 ``` The resulting carbocation is a secondary carbocation, which is more stable than a primary carbocation.
04

Formation of carbocation intermediate

With the ethylene protonated and the isobutane as a nucleophile, the carbocation can attack the isobutane, forming a new carbon-carbon bond. This process results in another carbocation intermediate: ``` CH2 | CH3 – C – CH3 | CH3 – C+ – H ``` #Step 3: Deprotonation to form 2,3-dimethylbutane#
05

Deprotonation of carbocation intermediate

The carbocation intermediate can be deprotonated to form a stable alkane. In this case, the loss of a proton leads to the formation of 2,3-dimethylbutane: ``` CH2 | CH3 – C – CH3 | CH3 – C – H ``` The overall reaction sequence leads to the formation of 2,3-dimethylbutane as the primary product, instead of neohexane.

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.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

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

Compound \(\mathrm{X}\) has the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8}\). Compound \(\mathrm{Y}\) is obtained when hydrogen bromide is added to \(\mathrm{X}\). Compound Y reacts with AgOH to form a tertiary alcohol. Identify all structures.

What is an alkene?

Indicate which of the following compounds show geometric (cis-trans) isomerism, draw the isomeric structures, and specify each as \(Z\) or \(E\). (a) 1-butane (g) 2 -pentene (b) 2-butane (h) 1-chloropropene (c) 1,1 -dichloroethene (i) 1 -chloro-2-methy1-2-butene (d) 1,2 -dichloroethene (j) 3 -methy \(1-4\) -ethy \(1-3\) -hexane (e) 2 -methy \(1-2\) -butane (k) 2,4 -hexadiene (f) 1-pentene \(\quad\left(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}=\mathrm{CHCH}_{3}\right)\)

Describe dehydration of alcohols to obtain an alkene.

Determine the oxidation number of each atom in the following: (a) propene (e) (E)-2-chloro-2-butane (b) 1-butane (f) \(1,1-\) dichloropropane (c) cis-2-butane (g) acetic acid, \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) (d) 1-chloro-2-butane (h) methanethiol, \(\mathrm{CH}_{3} \mathrm{SH}\)
See all solutions

Recommended explanations on Chemistry Textbooks

Chemical Analysis

Read Explanation

Making Measurements

Read Explanation

Organic Chemistry

Read Explanation

Kinetics

Read Explanation

Inorganic Chemistry

Read Explanation

Physical Chemistry

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.

Sign-up for free