1,2,3-Propantriol
(2006)
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CAS no
56-81-5
Synonyms
Glycerol, glycerine, E422
Physical data
Boiling point: 18 °C
Freezing point: 290 °C
Vapour pressure:
0,0003 kPa, (50°C)
Water solubility: completely miscible
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1,2,3-Propanetriol is a trihydric alcohol. It is a clear,
viscous liquid, with a sweet taste. It has low volatility and high
boiling point because the molecules form strong hydrogen bonds.
1,2,3-propanetriol is hygroscopic, which means that it can pick up and
give off water. It might absorb vaporous water from the air up to 50 %
of its weight. It is completely miscible with water but insoluble in
hydrocarbons. The name glycerine refers to the quality that contains
more than 95 % glycerol.
All animal and vegetable fats are esters of 1,2,3-propanetriol and fatty
acids, i.e. triglycerides. 1,2,3-propanetriol is recovered through
splitting of fats to fatty acids and 1,2,3-propanetriol. It is a
by-product in soap manufacturing. The substance is also formed in the
production of rape-oil methyl ester (RME), which is a substitute for
diesel oil. Since 1949 it has also been produced commercially by
synthesis from propene. Propene is chlorinated and hydrolyzed to
1,2,3-propanetriol. A newer method is to oxidize propene or propylene
oxide with oxygen or hydrogen peroxide over a catalyst.
The world use of glycerol during 2004 was over 300,000 tonnes. The
substance is used in nearly all industrial sectors. The largest single
use is in the manufacture of alkyd resins used in e.g. paints. In food
industry the substance is used as a solvent, moistening agent and an
ingredient in syrups among other things. It also retards crystallization
of sugar. In drugs and medicine glycerol or its derivatives are used as
an ingredient of many mixtures. In cosmetics 1,2,3-propanetriol is used
to keep the skin soft and replace skin moisture. In tobacco processing
the substance is sprayed on the tobacco leaves before they are shredded
and packed. It helps to retain the moisture and influences the burning
rate of the tobacco. The many OH-groups of 1,2,3-propanetriol is used to
crosslink the polymer chains in production of flexible polyurethane
foams. This use is increasing. 1,2,3-Propanetriol is used as lubricant
in production of food, drugs and cosmetics as well as for lubricating
pumps and bearings exposed to gasoline and benzene. Such fluids would
dissolve oil-type lubricants. Another use is for the production of
explosives, nitroglycerine.
In Sweden pure 1,2,3-propanetriol is mainly used in food production and
in hygienic and cosmetic products. It is also a part of many lubricants,
de-icing agents and is used as heat transmission agent. It is an
approved food additive with the denotation E422.
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