Patent ID: 7714124

Claim:
A method for preparing a modified, cellulose-based biopolymer, comprising reacting SO 3 , SO 3 .pyridine complex, or mixture thereof, with a cellulose or cellulose ether biopolymer, or mixture thereof, in a reaction medium comprising a substantially anhydrous ionic liquid, adding a recovery solvent to said reaction medium to precipitate said modified biopolymer and recycling the ionic liquid for re-use by drying said solvent to said substantially anhydrous state with a material that selectively ingests water without ingesting ionic liquid; wherein the ionic liquid comprises a cationic component including a heteroatom having substituents such that the heteroatom is a cationic center, said cationic component being selected from the group consisting of components having the following formulae: wherein the R 1 -R 8 substituents are independently selected from the group consisting of H, C1-C6 alkyl, alkenyl, hydroxyalkyl, haloalkyl, alkoxylalkyl; C6-C10 aryl or C8-C16 alkylenearyl; and mixtures thereof, with the proviso that the substituents at the cationic center not be H; and an anionic component selected from the group consisting of mono- or di-C1-C10 alkyl sulfosuccinates, mono- or di-C1-C10 ester sulfosuccinates, and mixtures thereof.