Page 5 - Microsoft Word - Sulfo and Sulfa 1.doc

directly to the ammonium salt of the alcohol sulfuric acid. Sulfamic acid is an expensive
reagent, costing approximately US$0.51 per pound of reactive SO . Sulfamic acid
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sulfation is a mild and specific sulfating reagent suitable for making ammonium
neutralized alcohol ethoxylates. Another major advantage of sulfamic acid is that it
selectively sulfates alcohol groups and will not sulfonate aromatic rings. Therefore, its
major use is sulfation of alkyl phenol ethoxylates. This specificity prevents formation of
mixed sulfate-sulfonate compounds. Sulfamic acid is easily handled and reacts
stoichiometrically with the alcohol or ethoxy alcohol. It readily adapts to making small
quantities of material in low cost batch equipment.

Figure 5. Sulfamic Acid Sulfation

CH - (CH ) (O - CH - CH ) - OH + NH SO H
2 4
2
2 8
3
2
3
Alkyl phenol ethoxylate Sulfamic Heat
Acid
O
+
CH - (CH ) (O - CH - CH ) - O - S - O NH 4 –
3
2 4
2
2 8
O
Alkyl phenol ethoxylate ammonium sulfate

Chlorosulfuric acid (ClSO H) is also widely used to produce alcohol sulfates, alcohol
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ether sulfates, dyes and dye intermediates. Figure 6 shows a typical reaction. Note that
as the reaction moves to completion, hydrochloric acid (HCl) is released. This acid must
be scrubbed or otherwise recovered. Chlorosulfuric acid is an expensive source of SO
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although it is approximately one half the cost of sulfamic acid. The cost per pound of
reactive SO is US$0.255. It is a rapid, stoichiometric reactant. However, it is still more
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expensive than other sources of SO . It is also corrosive and a hazardous chemical to
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handle and liberates HCl as a by-product during the reaction. The HCl can be recovered
by scrubbing the off-gas stream with water, or neutralized by scrubbing the off-gas with a
dilute basic scrubbing solution. In either case, additional equipment and complexity are
added to the process.

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