Liquid or gaseous sulfur trioxide is the most direct and cleanest route to sulfonation. Reactivity and selectivity can be individually adjusted according to processing conditions. CABB produces sulfur trioxide in our own integrated production system and discharge it directly from closed systems into multi-purpose reactors. In contrast to sulfonations with chlorosulfonic acid, oleum or sulfuric acid – no waste or side streams are generated.
Sulfonation with oleum and sulfuric acid
Oleum and sulfuric acid are widely used sulfonation and sulfation reagents, although reactions with these reagents require corrosion-resistant materials of construction. CABB has the dedicated assets to produce these and other sulfonation reagents for our custom manufacturing services and portfolio products.
Sulfonation and chlorosulfonation with chlorosulfonic acid
Chlorosulfonic acid is widely used for sulfonation reactions. An equimolar quantity leads to sulfonation, an excess to chlorosulfonation. Chlorosulfonic acid is manufactured in CABB’s integrated production system, offering a secure supply for customer requirements.
Sulfonation with sulfur trioxide-amine complexes
As a “transportable SO3,” sulfur trioxide-amine complexes represent an interesting alternative to chlorosulfonic acid, oleum or sulfuric acid. These complexes are easy-to-handle solids, with the choice of amine controlling the reactivity of the complex. Strong Lewis bases such as trimethylamine provide stability, while dimethylformamide leads to reactivity. The pyridine SO3 complex, the standard reagent of this class, shows a balanced behavior.
Widely used as a reagent for disinfection in the food industry and as a bleaching agent, sulfur dioxide is a key solvent for CABB. Why? SO3 sulfonations carried out in liquid sulfur dioxide at -20°C and are gentle and selective. Product isolation is achieved by increasing the reaction temperature above -10°C, where the sulfur dioxide evaporates and is collected for recycle.