Abstract: A process for converting a sulfolene feed, containing contaminating amounts of sulfur dioxide, to a sulfolane product in which the sulfolene feed is dissolved in a solvent selected from the group consisting of alcohols and ketones having at least six carbon atoms per molecule, slight solubility in water and a boiling point significantly above 100.degree. C., the thus formed sulfolene solution is distilled to reduce the sulfur dioxide content, the sulfolene solution and hydrogen are contacted with a hydrogenation catalyst to convert the sulfolene feed to a sulfolane product and the sulfolane product is recovered from the effluent of the contacting step.

Abstract: Inhibition of the formation of color bodies and color-forming materials and other contaminants and/or decolorization of discolored sulfur-containing organic compounds containing divalent sulfur by addition of a small amount of oxalic acid.

Abstract: Prior to hydrogenation to produce sulfolane, a sulfolene feed containing sulfur-containing catalyst poisons is contacted with used and/or at least partially spent Raney nickel catalyst under conditions which substantially remove and/or render innocuous the catalyst poisons. The pretreatment removes sulfur dioxide and polymeric sulfones from the sulfolene which would otherwise contaminate and deactivate the fresh catalyst employed in the hydrogenation.

Abstract: A process for converting sulfolene compounds to sulfolane compounds comprising contacting at least one sulfolene compound with hydrogen in the presence of a metal hydrogenation catalyst and an effective amount of ammonia as an SO.sub.2 neutralizer or scavenger. The addition of ammonia increases conversion of sulfolene to sulfolane, improves product color, and reduces polymer formation during hydrogenation. In a preferred embodiment, the ammonia is admixed with the hydrogen prior to contacting with the sulfolene compound.