Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 23: Problem 76

The hasicitydecreasing effect of nitro substitution in the s-position is almost entirely the result of its inductive effect, whereas that of nitro substitution in the 4.position is attributable to both inductive and resonance effects. In the case of para suhstitution (as well as ortho substitution), delocalization of the lone pair on the amino nitrogen involves not only the carbons of the aromatic ring but alwo oxy gen atoms of the nitro group.

Short Answer

Expert verified
Answer: The para position of nitro substitution leads to a greater decrease in basicity due to the combined effects of inductive and resonance effects, which weaken the lone pair on the nitrogen atom and decrease electron density.

Step by step solution

01

Introduction to inductive and resonance effects

Inductive effect is the electron withdrawing or donating ability of a group through the sigma bonds. Resonance effect is the ability of a group to stabilize or destabilize a compound through the delocalization of electrons via pi bonds.
02

Nitro group characteristics

Nitro group (-NO2) is an electron-withdrawing group (EWG) that decreases electron density in the molecule. This happens due to the inductive effect (through sigma bonds) and resonance effect (through pi bonds).
03

Analyzing s-position (ortho) substitution

When the nitro group is in the ortho position relative to the amino group, the electron withdrawal is almost entirely due to the inductive effect. This is because the distance between the nitro group and amino group is too close, allowing the inductive effect to dominate and weaken the lone pair on the amino nitrogen. This leads to a decrease in basicity.
04

Analyzing para-position (4) substitution

When the nitro group is in the para position relative to the amino group, the electron withdrawal is due to both inductive and resonance effects. The delocalization of the lone pair on the amino nitrogen not only involves the carbons of the aromatic ring but also the oxygen atoms of the nitro group. This weakens the lone pair on the nitrogen atom, leading to a decrease in electron density and a decrease in basicity.
05

Comparing s-position and para-position substitution

In the case of s (ortho) position substitution, the hasicity decrease is primarily due to the inductive effect. However, in the case of para (4) position substitution, both inductive and resonance effects contribute to the decrease in hasicity. In summary, the nitro substitution in the para-position results in a greater basicity decrease than in the ortho-position due to the combined effect of inductive and resonance effects.

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

IUPAC nomenclature retains the common name aniline for \(\mathrm{C}_{\mathrm{e}} \mathrm{H}_{3} \mathrm{NH}_{2}\), the simplest arcanatic amine. Its simple derinatives are named using the prefixes \(o, w\), and \(p\), or numbers to locate substituents. Several derivatives of aniline have common names that are still widely used. Among these are tolusdine for a methyd-suhatitusted aniline and anisidine for a methoxyl-substituted aniline.

The geometry of a nitrogen atom bonded to three other atoms or groups of atoms is trigonal pyramidal (Section 1.4). The sp, bybridized nitrogen atom is at the apex of the Pyramid, and the three groups bouded to it extend densaward to form the triangular base of the prramid. If we consider the unshared pair of electrons on nitrogen as a foeurth grosp, then the amrangement of "groups" around nitrogen is approximately tetrahedral. Berause of this geoenetry, an ansine with three different groups bonded to nitrogen is chiral and can exist as a pair of enantiomers, as illustrated by the nonsuperporable mirror images of ethyimethylamine. In assigning configuration to these enantiomers, the groxp of lowest prioxity on nitrogen is the unshared pair of electrons.

Write structural formulas for these amines. (a) Isobutylamine (b) Triphenylamine (c) Diixspropylamine

As a result of pyramidal inversion, a chiral amine quite literally tarns itself inside out, like an umbrella in a strong wind, and in the process becomes a racemic mixture. The activation energy for pyramidal inversion of simple amines is about \(25 \mathrm{~kJ}\) ( \(6 \mathrm{kal}) / \mathrm{mol}\). For ammonia at roon temperature, the rate of nitrogen inver sion is approximately \(2 \times 10^{11} \mathrm{~s}^{-1}\). For simple amines, the rate is less rapid but nonetheless sufficient to make resolution impossible. Pyramidal imversion is not possible for quaternary ammonium ions, and their salts can be resolved.

Like ammonia, all amines are weak bases, and aqueous solutions of amines are basic. The following acid-base reaction between an amine and water is written uxing curved arross to emphasize that, in these proton-transfer reactions, the unshared pair of electrons on nitrogen forms a new covalent bond with hydrogen and displaces hydroxide ion.
See all solutions

Recommended explanations on Chemistry Textbooks

Organic Chemistry

Read Explanation

Making Measurements

Read Explanation

Physical Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Inorganic Chemistry

Read Explanation

Nuclear 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