Poly-1-butenes are becoming ever more important in the commercial world. The commercially useful poly-1-butene is typically a highly isotactic material with a relatively high degree of crystallinity. Generally, poly-1-butene is produced from 1-butene in the absence of a diluent and a Ziegler-type catalyst. Diluents can be any of the many inert hydrocarbons such as n-hexane, heptane, gasoline, the monomer itself, a mixture of butene-1 and butene-2, as well as the chlorinated hydrocarbons. The reaction is typically carried out in the liquid phase with the poly-1-butene being dissolved therein. Upon completion of the polymerization reaction, the catalyst is typically deactivated and removed by any of the techniques and manipulations well known in the art such as by treating with an alcohol, an alcoholic solution of a mineral acid, dilute aqueous acid solutions or simply with the oxygenated water. The poly-1-butenes are relatively susceptible to oxidation and for that reason a catalyst removal process must be selected which avoids deleterious oxidation of the polymer. While dilute aqueous solutions of sulfuric acid are quite effective for dissolving and removing catalyst residues, these materials have a tendency to degrade the polymer. The alpha-hydroxysulfonic acids of the instant invention are excellent chelating agents and readily removed catalyst residues from solutions of poly-1-butene, and yet they do not degrade the polymer as would solutions of sulfuric acid.
Alpha-hydroxysulfonic acids have been disclosed in the literature (see for example U.S. Pat. Nos. 3,248,278 issued Apr. 26, 1966 and 4,113,842 issued Sept. 12, 1978) for use in the removal of metal ions from aqueous metal streams. The process of the instant invention uses alpha-hydroxysulfonic acids for the removal of ionic residues from non-aqueous systems.
USPTO Backgrounds
USPTO Backgrounds