Glycerol : properties Part 2

Glycerol properties

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Glycerol properties –

1. Reaction with HNO3 :

  When a cold mixture of concentrated HNO3 and concentrated H2SO4  react with glycerol, then glyceryl trinitrate is formed.It is an  important explosive.It is used in the preparation of dynamite.

2. Reaction with Acetic acid –

When glycerol reacts with acetic acid ,then glyceryl monoacetate, glyceryl diacetate , glyceryl triacetate are formed.

3. Reaction with Acetic anhydride-

When glycerol reacts with acetic anhydride ,then glyceryl monoacetate, glyceryl diacetate , glyceryl triacetate are formed.

4. Reaction with Acetyl Chloride-

When glycerol reacts with acetyl chloride ,then glyceryl monoacetate, glyceryl diacetate , glyceryl triacetate are formed.

5) Reaction with Oxalic acid –

a)  When glycerol reacts with  excess of oxalic acid at 100-110 degree C  then formic acid is formed.

b)  When glycerol reacts with  excess of oxalic acid at  260 degree C  then Allyl alcohol  is formed.

6) Oxidation –

a) Glycerol on oxidation with dil.HNO3 gives glyceric acid & tartronic acid.

b)  Glycerol on oxidation with conc.HNO3 gives glyceric acid.

c)  Glycerol on oxidation with Fenton’s reagent (H2O2 + FeSO4) or Bromine water in presence of Na2CO3 gives  a mixture of glyceraldehyde & dihydroxyacetone. Mixture of these two are known  as Glycerose.

Uses :

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1. As a sweetening agent in confectionery beverages and medicine.
2. It is used in the manufacture of dynamite.
3. In the preparation of good quality soap, hand lotions, vanishing creams, shaving creams and toothpastes.
4. In the preparation of non drying inks, printing inks and stamp-pad inks etc.

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Test of glycerol:

1. Acrolein test: when glycerol is heated with KHSO4,  very offensive odor is produced due to formation of acrolein. Its aqueous solution reduces fehling’s solution and  tollens reagent.
2. Dunstan’s test : A drop of phenolphthalein is added to borax solution ,then  pink color appears on adding glycerol, the pink color disappears. The pink color reappears on heating and disappears on cooling again.