Ethylene Glycol

Ethane 1, 2 diol

Preparation: Lab preparation by hydroxylation.

Manufacture

Physical properties:

It is highly viscous because of the presence of two OH bond it undergoes extensive intermolecular H-bonding. Same reason owes to high solubility in water and high boiling point.

Chemical properties

Reaction with sodium

(vii)Oxidation: Ethyelene glycol upon oxidation gives different products with different oxidising agents. For example.
(a)

(b) With periodic acid HIO₄ or lead tetraacetetate.

Also called malapride reaction.

Dehydration

Uses

• As a solvent.
• Antifreeze in the radiators of cars and aeroplanes.
• In manufacture of terylene and other polyester.

Glycerol (Propane 1, 2, 3 triol)

One of the most important trihydric alcohol.

Preparation:

(i) By Saponification of oils and fats.

(ii) From Propylene

(iii) Synthesis from its elements

PHYSICAL PROPERTIES

Highly viscous due to three ⎯OH group due to which it undergoes extensive intermolecular
H-bonding.

CHEMICAL PROPERTIES

(i) It undergoes reaction of both secondary and primary alcoholic group.

To replace the third hydroxyl group in either of two dichlorohydrins, PCl₅ or PCl₃ in fused.

3. Reaction with concentrated nitric acid and sulphonic acid-Nitrogen.

A mixture of glyceryl trinitrate and glyceryl dinitrate absorbed on Kieselguhr is called dynamite.

4. Reaction with KHSO₄ – Dehydration.

5. Oxidation.

1. With dil. HNO_3, a mixture of glyceric acid and tartronic acid is produced.
2. With conc. HNO_3, mainly glyceric acid is obtained.
3. With bismuth nitrate, only mesoxalic acid is formed.
4. Mild oxidising agents like bromide water, sodium hypobromite (Br_2/NaOH) and Fenton’s reagent (H₂O₂ + FeSO₄) give a mixture of glyceroldehyde and dihydroxyacetone. The mixture is called glycerose.
5. With periodic (HIO₄) acid.

(vi) With acidified potassium permanganate.

6. Reaction with phosphorous halides.

7. Reaction with monocarboxylic acids.

Glycerol reacts with monocarboxylic acids to form mono-, di- and tri- ester depending upon the amount of the acid used and the temperature of the reaction. An excess of the acid and high temperature favour the formation of trimesters. For example, with acetic acid, glycerol monoacetate, diacetate and triacetate may be formed.

8. Acetylation.

When treated with acetyl chloride, glycerol forms glycerol triacetate.

9. Reaction with oxalic acid

(i)
(ii)

Uses: Glycerol is used:

1. In the preparation of nitroglycerine used in making dynamite. Nitroglycerine is also used for treatment of angina pectoris.
2. As an antifreeze in automobile radiators.
3. In medicines like cough syrups lotions etc.
4. In the production of glyptal or alkyl resin (a cross – linked polyester obtained by the condensation polymerization of glycerol and phthalic acid) which is used in the manufacture of paints and lacquers.
5. In making non-drying printing inks, stamp colours, shoes polishes etc.
6. In the manufacture of high class toilet soaps and cosmetics since it does not allow them to dry due to its hydroscopic nature.
7. As a preservative for fruits and other eatables.
8. As a sweetening agent in beverages and confectionary.