Page 2 - Microsoft Word - Sulfo and Sulfa 1.doc

Sulfonation and Sulfation Processes

Norman C. Foster, Ph.D., P.E.

Introduction

Sulfonation and sulfation are major industrial chemical processes used to make a diverse
range of products, including dyes and color intensifiers, pigments, medicinals, pesticides
and organic intermediates. Additionally, almost 500,000 metric tons per year of lignin
sulfonates are produced as a by-product from paper pulping. Petroleum sulfonates are
widely used as detergent additives in lubricating oils. However, the majority of the 1.6
million metric tons of sulfonates and sulfates produced annually in the United States
[1]
are used as surfactants in laundry and consumer products applications. This chapter
focuses only on commercial techniques for production of detergent range sulfonates and
sulfates.

Basic Chemistry

Although sulfonates and sulfates are similar in structure, there are important differences.
Figure 1 shows the reaction to produce a sulfonate. Sulfur trioxide (SO ) reacts with an
3
organic molecule – in this case an alkyl benzene – to form a sulfur-carbon bond. One of
the characteristics of this process is that the resultant alkyl benzene sulfonic acid is a
stable molecule.

Figure 1. Sulfonation

O
–
SO + (CH ) - CH CH - (CH ) S – O H +
3
3
3
2 11
2 11
O
Sulfur Alkyl Benzene Alkyl Benzene Sulfonic Acid
Trioxide

Page 1 of 36 © 1997 The Chemithon Corporation