Sulfolane, purification

The rotating-disk contactor (RDC), developed in the Netherlands (158) in 1951, uses the shearing action of a rapidly rotating disk to interdisperse the phases (Eig. 15b). These contactors have been used widely throughout the world, particularly in the petrochemical industry for furfural [98-01-1] and SO2 extraction, propane deasphalting, sulfolane [126-33-0] extraction for separation of aromatics, and caprolactam (qv) [105-60-2] purification. Columns up to 4.27 m in diameter are in service. An extensive study (159) has provided an excellent theoretical framework for scale-up. A design manual has also been compiled (160). Detailed descriptions and design criteria for the RDC may also be found (161). 

Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysUoxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), sUylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stabUity. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

Lagowski, J. J., Ed., The Chemistry of Non-Aqueous Solvents, Academic, New York. This series contains detailed accounts of the purification, properties, and handling of some major solvents Vol. 2(1967), hydrogen halides, amides, and ammonia Vol. 3(1970), sulfur dioxide and acetic acid Vol. 4 (1976), tetramethylurea, cyclic carbonates, and sulfolane Vol. 5A (1978), tri-fluoroacetic acid, hafosuffuric acids, interhalogens, inorganic halides and oxyhalides. 

UOP/Shell BTX, purification Reformate, pyrolysis gasoline Shell Sulfolane process liquid extraction and/or extractive distillation with sulfolane solvent 123 1998... 

J. F. Coetzee (ed.) Recommended Methods for the Purification of Solvents and Tests for Impurities, Pergamon Press, Oxford, 1982. (Acetonitrile, Sulfolane, Propylene carbonate. Dimethyl sulfoxide, V,7V-Dimethylformamide, Hexamethylphosphoric tiiamide. Pyridine, 1,2-Diaminoethane, N-Methylacetamide, and V-Methylpropionamide). 

Sulfolane may be purified by fractional crystallization followed by fractional distillations at reduced pressure [396] alternatively, treatment with aqueous hydrogen peroxide, followed by extraction with CH2CI2 and fractional distillation, may be employed [393]. The purification procedures have been discussed [397]. 

The rotating disc contactor (B), developed in the Netherlands in 1951, uses the shearing action of a rapidly rotating disc to interdisperse the phases. These have been used in the petrochemical industry for furfural and SOj extraction, propane deasphalting, sulfolane extraction for the separation of aromatics from aliphatics, and caprolactam purification. Columns up to 4.3 m in diameter are in service. 

Because of the difficulty of isolating this very air- and moisture-sensitive complex, for synthesis the crude product is best used directly. The solvent is removed using vacuum distillation, and the oily residue is dissolved in either the neat ligand or a sulfolane or acetone solution of the ligand. The products are much less sensitive to oxidation, which facilitates the purification procedure. 

Sulfolane is used as a polymerization solvent for the production of polysulfones, polysiloxanes, polyphenylene ethers, and other polymers. Sulfolane is said to increase the reaction rates, afford easier polymer purification, and improved thermal stability. Sulfolane is a solvent for dissolving a variety of polymers for use in the fiber-spinning process. Cellulose and cellulose ester polymers can be plasticized with sulfolane to give improved flexibility and other physical property improvements [12,13]. Other application areas that have used sulfolane include electronic and electrical, textile-dye uses, curing of polysulfide sealant, and as a catalyst in certain synthetic reactions. 

---