Physical Properties It is colourless heavy liquid with specific gravity of 1.26. It is sweetish in taste and is commonly known as glycerine. It is soluble in water and alcohol but insoluble in lipid solvents like ether, chloroform, and benzene.
Glycerol is a component of fat. Its properties and reactions are described below. Glycerol is commonly called glycerine and is the alcoholic component of triglycerides. It is closely allied to carbohydrates in its chemical structure and properties, but it is closely associated with fats in its occurrence and function. The structure of glycerol is given below:
Addition reaction Isomerism: Unsaturated fatty acids may have isomers, depending upon two factors. One type of isomerism depends upon the position of double bond in the hydrocarbon chain – positional isomerism. Example: Oleic acid. There are sixteen positions where the double bonds may be placed. Hence, oleic acid forms sixteen isomers. Geometrical isomerism: It depends on the oxidation…
These are mainly due to the double bonds contained in the chain.
The carboxyl group condenses with alcohol to form esters. Triglyceride is an ester of fatty acid with glycerol. Cholesterol ester is formed by esterification of fatty acid with cholesterol. They are present in blood. The carboxyl group may be reduced to the corresponding aldehydes and alcohols in the presence of hydrogen at high temperature.
Soap formation: Fatty acids form salts (soaps) with alkalis because of the presence of a terminal carboxyl group. RCOOH + NaOH RCOONa + H2O
These are due to the carboxyl group and the hydrocarbon chain of fatty acid.
Physical Properties