Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 19: Q11P (page 997)

Propose a mechanism for nitration of pyridine at the 4-position, and show why this orientation is not observed.

Short Answer

Expert verified

This orientation is not observed because electrophilic substitution reaction at 4-position is not stable. The intermediate formed by electrophilic addition at 4-position is less stable than that of 3-position.

Step by step solution

01

Introduction

In above mechanism, addition of an electrophile to pyridine in the 4 position results in the formation of three resonance structures of the intermediate form.

02

Justification

Electronic substitution at 4th position is not stable because 4-position carbon is not the most electron rich C atom in the pyridine ring. Whereas 3-position carbon is the most electron-rich C-atom, therefore pyridine undergoes electrophilic substitution at 3 position rather than 4 position.

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

Show how to synthesize the following amines from the indicated starting materials by acylation–reduction.

(a) N-butylpiperidine from piperidine

(b) N-benzylaniline from anilinea

Addition of one equivalent of ammonia to 1-bromoheptane gives a mixture of heptan-1-amine, some dialkylamine, some trialkylamine, and even some tetraalkylammonium bromide.

  1. Give a mechanism to show how this reaction takes place, as far as the dialkylamine.
  2. How would you modify the procedure to get an acceptable yield of heptan-1-amine?

The two most general amine syntheses are the reductive amination of carbonyl compounds and the reduction of amides. Show how these techniques can be used to accomplish the following syntheses.

(a) benzoic acid to benzylamine

(b) benzaldehyde to benzylamine

(c) pyrrolidine to N-ethylpyrrolidine

(d) cyclohexanone to N- cyclohexylpyrrolidine

(e) HOOC-(CH2)3 -COOH to pentane-1,5-diamine cadaverine

Within each structure, rank the indicated nitrogens by increasing basicity.

Macrolide antibiotics all have large rings (macrocycle) in which an ester makes the ring; a cyclic ester is termed a lactone. One example is erythromycin A, first isolated from soil bacteria in the 1950’s. Over time, some pathogenic bacteria have developed resistance to erythromycin by evolving an enzymatic mechanism to cleave the macrocycle at the ketone. To counter this resistance, chemists modified the erythromycin structure to replace the ketone with an amine that the bacteria could not detoxify. This modified antibiotic, azithromycin, trade name Zithromax®, is one of the most prescribed drugs in the world for respiratory infections.

(a) Identify the lactone group in each structure that merits the classification as macrolides.

(b) Two groups are circled. What type of functional group are they? Explain

(c) Identify the ketone in erythromycin targeted by bacteria as the site for detoxification.

(d) Identify the amine in azithromycin. What type of amine is it?

(e) From what you know about the reactivity of ketones and amines, why was an amine a good choice to be the “chemical opposite of a ketone”?
See all solutions

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

Read Explanation

Organic Chemistry

Read Explanation

Inorganic Chemistry

Read Explanation

Physical Chemistry

Read Explanation

Making Measurements

Read Explanation

The Earths Atmosphere

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