Name: Diastereomers and Meso Compounds
Uploaded: 2019-07-19
Duration: 10 min 31 s
Description: Here, we will see how compounds with multiple stereocenters may be achiral if they have an internal plane of symmetry or an inversion centre. Let's explore.

Question

How many of the following compounds will accept $H^{\oplus}$ . from ammonium ion.

Pyridine, Aniline, Pyrrole, Triphenyl amine, Benzyl amine, Methyl amine, Di-methyl amine, Tri-methyl amine

Accepted Answer

In general words the basicity of any compound is the tendency to donate lone pair of electrons or accept proton $(H^{+})$ . The species which will donate electron density easily or accept proton easily will be more basic.

In pyridine, the lone pair of electrons are bound to ${sp}^{2}$ hybridised nitrogen atom which is more electronegative than ${sp}^{3}$ hybridised nitrogen atom of ammonia, and can not easily donate lone pair of electrons in order to accept $H^{+}$ , therefore it can not abstract proton from ammonium ion $({NH}_{4}^{+})$ .

In aniline, the lone pair of electrons of nitrogen atom is in resonance with benzene ring ( $- M$ -effect of phenyl group), and therefore it can not abstract proton from ammonium ion.

In pyrrole, the lone pair of electrons of nitrogen atom is the part of aromaticity. If it abstracts proton, the aromaticity will get destroy, and therefore it can not abstract proton from ammonium ion.

In triphenyl amine, the lone pair of electrons of nitrogen atom is in resonance with three benzene rings ( $- M$ -effect of phenyl group), and therefore it is very less basic and can not abstract proton from ammonium ion.

In benzyl amine also proton cannot be abstracted from ammonium ion because phenyl $(- C_{6} H_{5})$ group of it shows $- I$ -effect, due to which electron density on $N$ -atom of benzylamine decreases and also steric hindrance is more than that in ammonia.

Methyl amine, di-methyl amine, tri-methyl amine all have methyl $(- {CH}_{3})$ group attached to them which shows $+ I$ -effect and increases the electron density over $N$ -atom, therefore it easily donates its lone pair of electrons and abstracts proton from ammonium ion.

So the correct answer is $3$ .

How many of the following compounds will accept $H^{\oplus}$ . from ammonium ion.

Pyridine, Aniline, Pyrrole, Triphenyl amine, Benzyl amine, Methyl amine, Di-methyl amine, Tri-methyl amine

Important Questions on Organic Chemistry- Some Basic Principles and Techniques

Learn and Prepare for any exam you want !

How many of the following compounds will accept H⊕. from ammonium ion. Pyridine, Aniline, Pyrrole, Triphenyl amine, Benzyl amine, Methyl amine, Di-methyl amine, Tri-methyl amine

Important Questions on Organic Chemistry- Some Basic Principles and Techniques

Learn and Prepare for any exam you want !

How many of the following compounds will accept $H^{\oplus}$ . from ammonium ion.

Pyridine, Aniline, Pyrrole, Triphenyl amine, Benzyl amine, Methyl amine, Di-methyl amine, Tri-methyl amine