Difference Between Azo and Diazo

The key difference between azo and diazo is that the term azo refers to the presence of N=N group, whereas the term diazo refers to the presence of an azo group at the terminal of an organic compound.

Azo and diazo are two terms we can find in the field of organic chemistry. The term azo is used to name compounds containing the functional group N=N, and if this functional group is located at a terminal of the molecule, then we call it a diazo compound.

CONTENTS

1. Overview and Key Difference
2. What is Azo
3. What is Diazo
4. Side by Side Comparison – Azo vs Diazo in Tabular Form
5. Summary

What is Azo?

The term azo refers to the presence of an N=N functional group. In organic compounds, this functional group occurs in the form of R-N=N-R’ where R and R’ are either alkyl or aryl groups. The name azo originates from the term azote, which refers to the French name for nitrogen.

Aryl azo compounds are comparatively stable than alkyl azo compounds, and they usually occur in crystalline form. For example, azobenzene contains two benzene rings as R and R’ of the azo compound. It mainly exists in the trans isomeric form but it can convert into the cis isomer as well upon illumination. Azo coupling is the process from which we can produce azo compounds. It is a form of electrophilic substitution reaction.

Alkyl azo compounds contain alkyl groups attached to the azo functional group. We can call them aliphatic azo compounds. An example of a simple alkyl azo compound is diethyldiazene. It has two ethyl groups attached to the N=N functional group.

What is Diazo?

The term diazo refers to the presence of two nitrogen atoms attached to the terminal of an organic compound. The general structural formula for this type of compounds is R₂C=N⁺=N^–. An example of a simple diazo compound is diazomethane, which has an azo functional group attached to a methane molecule.

These diazo compounds can act as 1, 3-dipoles in cycloaddition reactions. Moreover, they can act as precursors for carbene production. In addition, they can react as nucleophiles in nucleophilic addition reactions. When considering the synthesis of diazo compounds, we can synthesize them from amines, from diazomethyl compounds, via diazo transfer, from hydrazones, etc.

What is the Difference Between Azo and Diazo?

The key difference between azo and diazo is that the term azo refers to the presence of N=N group, whereas the term diazo refers to the presence of an azo group at the terminal of an organic compound. In azo compounds, the N=N functional group occurs at the middle of the compound where the two terminals of the functional group are attached with some other substituent groups. In contrast, in diazo compounds, the functional group occurs at the terminal of the compound. The general chemical formula for an azo compound is R-N=N=R’, while the general chemical formula of a diazo compound is R₂C=N⁺=N^–.

There are two types of azo compounds as alkyl and aryl azo compounds. A simple example of an aryl azo compound is azobenzene. A simple example of a diazo compound is diazomethane.

Below infographic summarizes the difference between azo and diazo.

Summary – Azo vs Diazo

The terms azo and diazo come mainly under the field of organic chemistry. The key difference between azo and diazo is that the term azo refers to the presence of N=N group, whereas the term diazo refers to the presence of an azo group at the terminal of an organic compound.

Reference:

1. “Azo Compound.” Wikipedia, Wikimedia Foundation, 18 Oct. 2019, Available here.
2. “Diazo.” Wikipedia, Wikimedia Foundation, 6 Aug. 2019, Available here.

Image Courtesy:

1. “Azo-group-2D-flat” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “DiazoResonance” By Wereon – Own work (Public Domain) via Commons Wikimedia