| abstract |
A method of removing a carboxylic acid from a liquid including a tertiary amide solvent includes the steps of: A) forming an extraction medium comprising an acid-extracting tin species and an extraction solvent that is immiscible with the tertiary amide solvent; B) subsequently contacting the liquid including the tertiary amide solvent with said extraction medium, thereby forming a phase including a de-acidified tertiary amide solvent and a phase including the extraction solvent; and C) removing the phase including the extraction solvent, to afford a liquid including the de-acidified tertiary amide solvent; wherein the acid-extracting tin species is selected from the group consisting of tin species obtainable by reaction of a di(hydrocarbyl) tin oxide with less than one equivalent of a carboxylic acid, tin species obtainable by reaction of a 1,3-diacyloxy- 1,1,3,3-tetra-(hydrocarbyl)distannoxane with an aqueous base, and combinations of these. |