Synthetic Detergents:
an historical perspective
The term "synthetic detergent" is used throughout this article, for a
material which cleans (or is used for cleaning), but in this definition soap is not
included. Even so, this is still a wide definition, because, of course, it can refer to
the active ingredient, or the solid, liquid, paste or powder compounded from this active
matter. However, this should not lead to confusion, as the industry itself as yet makes no
distinction in terminology between the basic material and the ready-for-use product.
The first synthetic detergents which fall into our definition of the term seem
to have been developed by the Germans in the First World War period to allow fats to be
utilized for other purposes. These detergents were of the short-chain alkyl naphthalene
sulphonate type, made by coupling propyl or butyl alcohols with naphthalene and subsequent
sulphonation, and appeared under the general name of Nekal. These products proved to be
only fair to moderately good detergents, but good wetting agents and are still being
produced in large quantities for use as textile auxiliaries.
In the late 1920s and early 1930s long-chain alcohols were sulphonated and sold
as the neutralized sodium salts without any further additions except for sodium sulphate
as an extender.
In the early 1930s long-chain alkyl aryl sulphonates with benzene as the
aromatic nucleus, and the alkyl portion made from a kerosene fraction, appeared on the
market in the USA. Again, these were available as the sodium salts extended with sodium
sulphate. Both the alcohol sulphates and the alkyl aryl sulphonates were sold as such as
cleaning materials, but did not make any appreciable impression on the total market. At
the end of the Second World War alkyl aryl sulphonates had almost completely swamped the
sales of alcohol sulphates for the limited uses to which they were applied as general
cleaning materials, but the alcohol sulphates were making big inroads into the shampoo
field. An exception was Teepol, a secondary alcohol sulphate which remained popular for
some years.
In common, however, with other chemical developments during this century,
progress was not in one direction only. The limiting factor is always the availability of
raw materials in a particular country. Con-currently with the above developments, there
were developed, both in Germany and the USA, the lgepon type of compounds of which
lgepon-T, the sodium salt of oleyl tauride is an example, and in Germany the Mersolates,
which are alkane sulphates. In the United Kingdom, Teepol, a secondary olefine sulphate
from petrochemical sources, was manufactured in large quantities and is still being
produced in England and western Europe to this day.
Each of these basic materials has its advantages and disadvantages, but in
considering the feasibility of production the following factors must be taken into
account:
- availability of raw materials;
- ease of manufacture;
- cost of raw materials;
- cost of manufacture;
- suitability of finished product.
We have purposely placed suitability last, as it is only too true that not
always is the best material made available.
As a result of its ease of manufacture and versatility, the alkyl benzene
sulphonate very quickly gained a foothold in the market, and after the last war the
existing keryl benzene was very quickly replaced by an alkyl benzene made from propylene
tetramer coupled to benzene (PT benzene).
This PT benzene very quickly displaced all other basic detergents and for the
period 1950-65 considerably more than half the detergents used throughout the world were
based on this.
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