Reaction Intermediates - Definition, Types, and Properties

In this article we will learn about Reaction intermediates in chemistry. Here we will discuss  Definition, Types, and Properties of reaction intermediates. 

An intermediate species is certain unstable species formed in chemical reaction. They are highly reactive, unstable and often decomposes to neutral and stable species. 

There are five types of intermediate found in chemistry namely; Radical, Carbocation, Carbanion, Carbene, Benzyne intermediates.  

Introduction

Any chemical reaction proceeds through certain unstable species to produce final product. This unstable species are known as “intermediates”.

Consider a hypothetical reaction in which compound A and compound B reacts with each other to form compound C. In the course of reaction A and B combines to form certain species which is known as intermediate. The structure of the intermediate will be similar to the final product. 

What is an Intermediate?

Intermediate species have following properties;

• Short lived
• High-energy
• Highly reactive 
• Quickly convert into more stable molecule
• Do not obey Lewis octet rule

Why to study reaction intermediates?

Study of reaction intermediate is important because;

• It gives an idea about reaction mechanism.
• To understand structure of final product.
• To study reactivity of various reactants / compounds

How to study reaction intermediates?

There are some methods by which we can find out intermediate species in the given reactions. They are spectroscopic methods and isolation / trapping of intermediate species.

The spectroscopic methods are non-destructive methods. That means the reactive species is analyzed as it formed in the reaction mixture. The available techniques are listed below;  

Detection of an Intermediate by

• Infra Red spectroscopy
• Raman spectroscopy;
• Mass spectroscopy
• Electron Spin Resonance   (ESR)

Trapping of an Intermediate

In this method the reaction is stopped by other reactive compound to form neutral compound. The formed compound then isolated and analyzed by various spectroscopic methods to understand the structure of compound.

Types of Carbon Intermediates

• Radical
• Carbocation
• Carbanion
• Carbene
• Benzyne or aryne 

Properties of Reactive intermediates

We will see each of the intermediate in detail in coming article. That's all for this topic. If you have any questions please feel free to ask me in the comment box. Thank you..!