Structure of Fructose
The structure of fructose is cyclic or chair-like. There are a few deviations to the general structure of fructose, but its overall form is largely identical to that of glucose. The functional group of fructose is ketone, and the ring closure starts at the second carbon position.
This causes fructose to form an intramolecular hemiacetal or to ascend to a 5-membered ring. The carbon at the second position mixes with the OH at the fifth carbon.
There are four carbons and one oxygen in the five-membered ring. In essence, there are two configurations of -CH2OH and -OH groups as well as a creation of chiral carbon. Fructose essentially exhibits stereoisomerism.
Ring Structure of Fructose
Fructose is a levorotatory monosaccharide, which means it rotates the plane-polarised light in the left direction. The chemical composition of fructose is C6H12O6 but shows different bonding from glucose. Fructose is a hexose, however, it exists as a 5-member hemiketal ring. The hemiketal ring helps with a long metabolic pathway and high reactivity in comparison to glucose.
Formation of Ring Closure Structure of Fructose (Hemiketal Synthesis)
Ether is formed when the carbon atoms in the alcohol oxygen are bonded together using the electrons present in the oxygen.
A new OH bond is formed when the hydrogen is moved to the carbonyl oxygen, giving fructose’s keto structure a ring like structure.
The carbon, which is the center of the hemiketal functional group, is referred to as anomeric carbon. The hemiketal group has both an ether oxygen and an alcohol group which is attached to two other carbons. Crystalline fructose possesses a ring structure. It is a 6 – carbon polyhydroxy ketone.
It gains stability by hemiketal and internal hydrogen bonding. In this form it is called D – fructopyranose while in its water solution fructose occurs as an equilibrium mixture of 70% fructopyranose and 22% fructofuranose and 7% three other forms including its acyclic structures.
What is Fructose?
Fructose is a simple sugar, also called “fruit sugar”. Fructose is a monosaccharide like glucose and is found in all types of fruits hence, the name fruit sugar. Fructose has four calories per gram. Fructose also occurs in various foods such as honey, sugar cane, corn, etc.
In this article, we will learn about Fructose, its structure, preparation, properties, uses, and comparison between glucose and fructose.
Table of Content
- What is Fructose?
- Structure of Fructose
- Properties of Fructose
- Physical Properties of Fructose
- Chemical Properties of Fructose
- Difference between Glucose and Fructose