Question

What is meant by Schiff’s base? Give an example of the reaction in each case.

Answer 1

Hint: A scientist Hugo Schiff, discovered Schiff base. Its general formula is $R_1{R}_{2}C=N{R}^{\prime }$, where $R\ne H$. They are common ligands in coordination chemistry. They are used to form catalysts which are necessary in many chemical reactions.

Complete step by step answer:
Schiff base is a subclass of imines which depending upon the structure can either be secondary ketimines or secondary aldehyde.
In the compounds, an imine or azomethine group has replaced the carbonyl group of aldehyde or ketone.
Synthesis of Schiff base can be explained as below:

In the reaction, the carbon atom of aldehyde or ketone which is electrophilic in nature is targeted by nucleophilic amines. The formed product shows a replacement of $C=O$ bond with $C=N$ bond in Schiff base.
An example of Schiff base formation can be seen in the reaction of conversion of opsin into rhodopsin upon reaction with $11$-cis-retinal

In the photoreception mechanism in human eyes, the retinal cofactor forms rhodopsin schiff base. It was discovered in eyes by the use of Roman spectroscopy.

Additional information:
Schiff base has been proved as an excellent source for the production of antimalarial drugs, antibiotics, antifungal drugs, etc.
These properties of Schiff base have helped to save thousands of lives all around the world

Note:
Hugo Schiff also gave a test, known as Schiff test. This test is used for the detection of aldehyde compounds in biological tissues. The aldehyde compounds are also present in the skin of humans, which can be conveniently tested with Schiff test.