Page 3 - Microsoft Word - Sulfo and Sulfa 1.doc
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Sulfation, on the other hand, involves forming a carbon-oxygen-sulfur bond as shown in
Figure 2. The resultant alcohol sulfuric acid is not hydrolytically stable. Unless
neutralized, it decomposes to form sulfuric acid and the original alcohol.
Figure 2. Sulfation
O
– +
SO + CH - (CH ) - CH - OH CH - (CH ) - CH - O - S - O H
3
2
3
2 10
2
3
2 10
O
Sulfur Primary Alcohol
Trioxide Alcohol Sulfuric Acid
Because they are stable, sulfonic acids can be isolated, stored and shipped as an article of
commerce. Sulfates, due to their instability, are available only as neutral compounds.
This stability difference in the products of reaction with SO also has a profound impact
3
on the choice of process used to produce sulfonates or sulfates. Some processes, such as
oleum sulfonation, cannot be used to make alcohol sulfates containing a low level of
inorganic sulfate. However others, such as sulfamic acid sulfation, cannot be used to
make sulfonic acids.
SO is an aggressive electrophilic reagent that rapidly reacts with any organic compound
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containing an electron donor group. Sulfonation is a difficult reaction to perform on an
industrial scale because the reaction is rapid and highly exothermic, releasing
approximately 380 kJ/kg SO (800 BTUs per pound of SO ) reacted . Most organic
[2]
3
3
compounds form a black char on
contact with pure SO due to the Figure 3. Viscosity Increase on Sulfonation
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rapid reaction and heat evolution.
Additionally, as shown in Figure
Acid
Feed
3, the reactants increase in Viscosity Viscosity
viscosity between 15 and 300 Feedstock (cp) @ 40 - 50°C
times as they are converted from
the organic feedstock to the Linear alkyl benzene 5 400
sulfonic acid . This large Branched alkyl benzene 15 1000
[1]
increase in viscosity makes heat Ethoxylated alcohol 20 500
removal difficult. The high Tallow alcohol 10 150
viscosity of the formed products Alpha olefins 3 1000
reduces the heat transfer
coefficient from the reaction mass.
Effective cooling of the reaction mass is essential because high temperatures promote
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