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A method of removing a carboxylic acid from a liquid including a tertiary amide solvent includes: forming an extraction medium including an acid-extracting tin species and an extraction solvent that is immiscible with the tertiary amide solvent; subsequently contacting the liquid with the extraction

A method of removing a carboxylic acid from a liquid including a tertiary amide solvent includes: forming an extraction medium including an acid-extracting tin species and an extraction solvent that is immiscible with the tertiary amide solvent; subsequently contacting the liquid with the extraction medium, forming a phase including a de-acidified tertiary amide solvent and a phase including the extraction solvent; and removing the phase including the extraction solvent, to afford a liquid including the de-acidified tertiary amide solvent. The acid-extracting tin species is one or more tin species obtained by reaction of a di(hydrocarbyl) tin oxide with less than one equivalent of a carboxylic acid, or tin species obtainable by reaction of a 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane with an aqueous base. A method of preparing a sucralose-6-acylate includes uses the foregoing method to remove a carboxylic acid from a liquid including a tertiary amide solvent and the sucralose-6-acylate.

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1. 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

1. 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; andC) 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. 2. The method of claim 1, wherein the solution comprising the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane in the extraction solvent comprises the phase comprising the extraction solvent removed in step C. 3. The method of claim 1, further comprising a step of water-washing the solution comprising the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane before the step of contacting said solution with the aqueous base. 4. The method of claim 1, further comprising a step of water-washing the extraction medium before said step of contacting the liquid comprising the tertiary amide solvent with said extraction medium. 5. 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; andC) removing the phase comprising the extraction solvent, to afford a liquid comprising the de-acidified tertiary amide solvent;wherein the acid-extracting tin species is cold species obtained by reaction of a 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane with an aqueous base, wherein less than one equivalent of aqueous base is used per acyloxy group on the diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane. 6. The method of claim 1, wherein the acid-extracting tin species is a di(hydrocarbyl) tin oxide. 7. The method of claim 1, wherein the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane is 1,3-diacetoxy-1,1,3,3-tetrabutyldistannoxane. 8. The method of claim 1, wherein the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane is 1,3-dibenzoyloxy-1,1,3,3-tetrabutyldistannoxane. 9. The method of claim 1, wherein the tertiary amide solvent is selected from the group consisting of dimethyl formamide, diethyl formamide and dibutyl formamide. 10. The method of claim 1, additionally comprising a step of distilling or evaporating and condensing the tertiary amide solvent. 11. The method of claim 1, additionally comprising a step of washing the liquid comprising a tertiary amide solvent with an additional portion of the extraction solvent prior to step B. 12. The method of claim 1, additionally comprising a step of washing the de-acidified tertiary amide solvent resulting from step C with an additional portion of the extraction solvent to remove residual tin compounds. 13. The method of claim 1, wherein the extraction solvent comprises one or more solvents selected from the group consisting of cyclohexane, n-heptane, toluene, and isooctane (2,2,4-trimethylpentane). 14. The method of claim 1, wherein the carboxylic acid that is removed comprises acetic acid. 15. The method of claim 1, wherein the tertiary amide solvent constitutes 30 to 100 wt % of said liquid comprising a tertiary amide solvent. 16. The method according to claim 1, wherein the method removes more than 50% of the carboxylic acid originally present. 17. The method according to claim 1, wherein steps B and C are repeated. 18. The method according to claim 17, wherein the method removes more than 85% of the carboxylic acid originally present. 19. The method of claim 1, further comprising forming a solution of sucrose in the resulting tertiary amide solvent and subsequently converting the sucrose to sucralose. 20. The method of claim 19, wherein said converting comprises converting the sucrose to a sucrose-6-acylate and subsequently converting the sucrose-6-acylate to sucralose. 21. The method of claim 20, wherein the sucrose-6-acylate is sucrose-6-acetate. 22. The method of claim 1, wherein both the liquid comprising the tertiary amide solvent and the liquid comprising de-acidified tertiary amide solvent further comprise a sucrose-6-acylate. 23. The method of claim 22, further comprising converting the sucrose-6-acylate to sucralose. 24. The method of claim 22, wherein the sucrose-6-acylate is sucrose-6-acetate. 25. A method of preparing a sucrose-6-acylate, comprising, in order, the steps of: (i) providing a first reaction mixture comprising sucrose, a tertiary amide solvent and an organotin-based acylation promoter;(ii) removing water from the first reaction mixture to afford a second reaction mixture that is substantially free from water;(iii) adding a carboxylic acid anhydride to the second reaction mixture to afford a third reaction mixture, thereby producing a sucrose-6-acylate; and(iv) removing carboxylic acid from the third reaction mixture by a method according to claim 1. 26. The method of claim 25, further comprising converting the sucrose-6-acylate to sucralose. 27. The method of claim 25, wherein the sucrose-6-acylate is sucrose-6-acetate. 28. The method of claim 5, wherein the solution comprising the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane in the extraction solvent comprises the phase comprising the extraction solvent removed in step C. 29. The method of claim 5, further comprising a step of water-washing the solution comprising the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane before the step of contacting said solution with the aqueous base. 30. The method of claim 5, further comprising a step of water-washing the extraction medium before said step of contacting the liquid comprising the tertiary amide solvent with said extraction medium. 31. The method of claim 5, wherein the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane is 1,3-diacetoxy-1,1,3,3-tetrabutyldistannoxane. 32. The method of claim 5, wherein the 1,3-diacyloxy-1,1,3,3-tetra-(hydrocarbyl)distannoxane is 1,3-dibenzoyloxy-1,1,3,3-tetrabutyldistannoxane. 33. The method of claim 5, wherein the tertiary amide solvent is selected from the group consisting of dimethyl formamide, diethyl formamide and dibutyl formamide. 34. The method of claim 5, additionally comprising a step of distilling or evaporating and condensing the tertiary amide solvent. 35. The method of claim 5, additionally comprising a step of washing the liquid comprising a tertiary amide solvent with an additional portion of the extraction solvent prior to step B. 36. The method of claim 5, additionally comprising a step of washing the de-acidified tertiary amide solvent resulting from step C with an additional portion of the extraction solvent to remove residual tin compounds. 37. The method of claim 5, wherein the extraction solvent comprises one or more solvents selected from the group consisting of cyclohexane, n-heptane, toluene, and isooctane (2,2,4-trimethylpentane). 38. The method of claim 5, wherein the carboxylic acid that is removed comprises acetic acid. 39. The method of claim 5, wherein the tertiary amide solvent constitutes 30 to 100 wt % of said liquid comprising a tertiary amide solvent. 40. The method according to claim 5, wherein the method removes more than 50% of the carboxylic acid originally present. 41. The method according to claim 5, wherein steps B and C are repeated. 42. The method according to claim 41, wherein the method removes more than 85% of the carboxylic acid originally present. 43. The method of claim 5, further comprising forming a solution of sucrose in the resulting tertiary amide solvent and subsequently converting the sucrose to sucralose. 44. The method of claim 43, wherein said converting comprises converting the sucrose to a sucrose-6-acylate and subsequently converting the sucrose-6-acylate to sucralose. 45. The method of claim 44, wherein the sucrose-6-acylate is sucrose-6-acetate. 46. The method of claim 5, wherein both the liquid comprising the tertiary amide solvent and the liquid comprising de-acidified tertiary amide solvent further comprise a sucrose-6-acylate. 47. The method of claim 46, further comprising converting the sucrose-6-acylate to sucralose. 48. The method of claim 46, wherein the sucrose-6-acylate is sucrose-6-acetate. 49. A method of preparing a sucrose-6-acylate, comprising, in order, the steps of: (i) providing a first reaction mixture comprising sucrose, a tertiary amide solvent and an organotin-based acylation promoter;(ii) removing water from the first reaction mixture to afford a second reaction mixture that is substantially free from water;(iii) adding a carboxylic acid anhydride to the second reaction mixture to afford a third reaction mixture, thereby producing a sucrose-6-acylate; and(iv) removing carboxylic acid from the third reaction mixture by a method according to claim 5. 50. The method of claim 49, further comprising converting the sucrose-6-acylate to sucralose. 51. The method of claim 49, wherein the sucrose-6-acylate is sucrose-6-acetate.