Glycerol is a trihydric alcohol whose IUPAC name is propane-1, 2, 3-triol and in industry it is known as glycerine.When glycerol is heated with excess of HI,the allyl iodide formed first is reduced to propene.Propene in presence of excess of HI forms iso-propyl iodide.So option (b) will be the correct answer.

						

							
Glycerol or Glycerine
 
Table of Content
Manufacture of Glycerol
​Properties of Glycerol
Uses of Glycerol
Dunstan's test for Glycerol

Glycerol is a trihydric alcohol. Its IUPAC name is propane-1, 2, 3-triol and in industry it is known as glycerine.
     

Manufacture of Glycerol
1.  From Fats and Oils : On hydrolysis of fats and oils (i.e. glycerides or ester of higher fatty acids) glycerol and fatty acids are formed.
    
Glycerol is obtained as by-product in soap and candle industry.
2.By Fermentation of sugar :
Alcoholic fermentation of sugar gives 3% glycerol. However, if the fermentation is done in presence of sodium sulphite, the yield can be increased to 25%.
    
3.  Synthesis (From Propene):
    

​Properties of Glycerol
Physical
(a)It is a colourless, odourless, viscous and hygroscopic liquid, sweet in taste and non-toxic in nature.
(b)It is soluble in water and ethyl alcohol but insoluble in ether.
(c)The high viscosity and high boiling point of glycerol are due to strong hydrogen bonding.
Chemical :
The molecule of glycerol contains two primary -OH groups and one secondary -OH group. The carbon atoms in glycerol are indicated as α,β and α'