Schiff Bases: Their Chemistry and Applications
by Yuvi K - January 7, 2024
Schiff Bases: Their Chemistry and Applications
A Schiff base is an organic compound derived from the reaction between an aldehyde or ketone and an amine. It was first coined in 1864 by Hugo Schiff, who recognized the reaction between ammonia and benzaldehyde. Schiff bases are versatile organic compounds that are used in a variety of applications in the chemical, pharmaceutical and diagnostic industries.
Structure of Schiff Base
The structure of a Schiff base consists of a planar nitrogen atom connected to two aryl or aliphatic groups – one is a nucleophilic group, such as an alcohol or amine, and the other is an electrophilic group, such as an aldehyde or ketone. In the stirring of aldehyde and primary amines,ranging from methyl to triethyl amine, a red-orange colored liquor is formed and cooled, resulting in gelation.
Synthesis Of Schiff Base
The synthesis of Schiff bases involves two main steps. The first step entails the reaction of an aldehyde or ketone with an amine. This reaction is called condensation and results in the formation of an initially unstable Schiff base. The second step involves the oxidation of the amino group of the Schiff base, which results in the formation of a carbon-nitrogen double bond (C=N). This oxidation reaction is typically performed with a hydroxide, such as sodium hydroxide or potassium hydroxide.
Uses of Schiff Base
Schiff bases have diverse applications, ranging from medicinal to industrial uses.
1. Medicinal Uses:
Schiff bases are used in the pharmaceutical industry as anticancer agents, antimicrobial agents and antifungal agents. For example, a Schiff base called d-ribo is used in the treatment of cancer. d-ribo has been found to decrease cell viability in various types of carcinomas and have been used in various clinical trials.
2. Industrial Uses:
Schiff bases are also used in the industrial sector in a variety of applications. Schiff bases have been used as catalysts for organic reactions such as oxidation or hydrolysis. They have also been used as reagents in the synthesis of organic compounds as well as in the preparation of polymers.
3. Diagnostics:
Schiff bases are used in the development of biological and chemical sensors for the detection of various analytes such as proteins and carbohydrates. In this regard, Schiff bases have been extensively used in the development of enzyme immunoassays for the detection of various analytes.
Molecular Mechanism of Schiff Bases
The molecular mechanism of Schiff base involves the formation of an intermediate, imine, and then the oxidation of this intermediate to form the actual product. In the initial stage, a nucleophile (an amine) attacks an aldehyde or ketone molecule’s carbonyl carbon atom, forming a covalent bond. In the next step, the intermediate, an imine, is formed by the removal of a proton from the amine, by the aldehyde or ketone. Finally, the imine undergoes oxidation, either by an oxidizing agent such as hydrogen peroxide or potassium permanganate, to form the actual product, a Schiff base.
Summary
Schiff bases are organic compounds derived from the reaction between an aldehyde or ketone and an amine. They have diverse applications, ranging from medicinal to industrial and diagnostic uses. The molecular mechanism of Schiff base involves two main steps, namely condensation and oxidation. The condensation stage involves the reaction between an aldehyde or ketone and an amine. The oxidation stage involves the oxidation of the amino group of the Schiff base, resulting in the formation of a carbon-nitrogen double bond.
