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Uses and reactions
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In this page i will go into details of a few of the uses of epoxyethane starting
with......
- Hydrolysis
The most sommon reaction of epoxyethane is the reaction with water in the presence
of an acid catalyst (usually dilute H2SO4) at a temperature
of about 333K. The product is Ethane-1,2-diol and the equation is shown below.
("structure of ethane-1,2-diol" image courtesy of chem-pics)
The water used has to be in large excess to try to prevent the product from reacting
with the original epoxyethane. As Ethane-1,2-diol itself is an alcohol
(because it contains simple -OH groups), and alcohols can react with epoxyethane.
(we'll be seeing this later).
Uses of Ethane-1,2-diol
Ethane-1,2-diol is used as an antifreeze in car engines. It is added to the
cooling water to prevent it from freezing under very cold conditions.
It is also used in the manufacture of polyesters such as
poly(ethylene terephthalate).
- Reactions with alcohols
Epoxyethane reacts with alcohols with this general equation. ("R" denotes a functional group)
Products of this type are used as solvents.
I mentioned earlier that water must be in excess when it is reacted with epoxyethane.
This is because the product of that reaction is an alcohol and can itself react.
Notice that in the two reactions above the products a are still alcohols.
It has an -OH group at the right-hand end of the molecules.
If the epoxyethane is in excess, the reactions will continue.
(In fact, it continues to some extent even if the epoxyethane isn't in excess.)
This is the same for any alcohol/epoxyethane reaction.
Eventually the products will keep reacting with the excess epoxyethane and form
a chain with a structure:
Compounds of this type are used as plasticisers
(added, for example, to PVC to make it more flexible) or as non-ionic surfactants
(detergents). To make the surfactant, you would start with a fairly long chain alcohol
to produce a molecule such as:
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