Patent ID: 8796446

Claim:
A method of removing a carboxylic acid from a liquid comprising a tertiary amide solvent, comprising 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 comprising the tertiary amide solvent with said extraction medium, thereby forming a phase comprising a de-acidified tertiary amide solvent and a phase comprising the extraction solvent; and C) removing the phase comprising the extraction solvent, to afford a liquid comprising the de-acidified tertiary amide solvent; wherein said step A) of forming the extraction medium comprises contacting a solution comprising a 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane in the extraction solvent with aqueous base to thereby form an aqueous phase and the extraction medium as a separate phase, and removing the aqueous phase.