glycerol properties

glycerol properties

source :

Propane-1,2,3-triol or glycerol


Structure of Glycerol:

source : Nutrients

Glycerol properties-

Physical properties:

1)  It is colorless, odorless, viscous and hydroscopic liquid.

2) It is sweet in taste and non-toxic in nature.

3) It is soluble in water due to formation of hydrogen bonding .

4) It has high boiling point i.e 2900C. The high viscosity and high boiling point of glycerol are due to association through H-bonding.

source :

Chemical properties:

The molecule of glycerol contains two primary  alcoholic (-OH)  group  and one secondary  alcoholic (-OH) group hence it shows characteristics of both primary and secondary alcohols. Primary -OH groups are more reactive than secondary -OH group.

1. Reaction with Sodium ( Na) :

 Primary alcoholic groups react with sodium one by one and secondary alcoholic  group does not react. Then  Mono sodium glycerolate is obtained at room temperature while disodium glycerolate at higher temperature.


2. Reaction with PCl5: 

All three -OH groups are replaced by Cl atoms and glyceryl tri chloride is formed.


3. Reaction with HCl :

when HCl is passed into glycerol  at 110oC  then   glycerol-α- monochloro hydrin &  glycerol-β- monochlorohydrin are formed. If HCl gas is passed for sufficient time then  glycerol-α, α’-dichlorohydrin and glycerol-α,β- dichlorohydrin are formed.


4. Reaction with HBr :

When HBr reacts  at 110oC  then   glycerol-α- mono bromo hydrin &  glycerol-β- mono bromo hydrin are formed. If HBr reacts  for sufficient time then  glycerol-α, α’-di bromo hydrin and glycerol-α,β- di bromo hydrin are formed.

5. Reaction with HI :

a) When glycerol  is warmed with  small amount of HI then  allyl iodide is formed.

b)        When glycerol  is heated with  large amount of HI, then  allyl iodide  first  formed  is  reduced to propene . In  presence of  excess of HI  iso-propyl iodide is formed. 


6) Dehydration:

 Glycerol  when heated alone or with dehydrating agents such as KHSO4 or P2O5 or concentrated H2SO4, then  acrolein or acraldehyde is formed, which has a characteristic bad smell.