isobutyl methyl ketone. An ion chromatography analysis of the organic phase showed an ammonium content of <l 00 ppm. 

[0137] Extraction ofMHA from a 10% MHA ammonium salt solution with isobutyl methyl ketone in a countercurrent extractor (inventive) 43 .3 g (239 mmol, M= 167 .2 g/mol, with a content of92.3%) ofMHA ammonium salt were dissolved in 356.7 g of water. This 10% salt solution was initially charged in the reservoir vessel of the countercurrent extractor (FIG. 2) and heated to 80° C. 1333 g ofisobutylmethylketone were likewise heated to 80° C. in the solvent reservoir. The extractor colunm was filled at the start with aqueous salt solution. During the extraction, 60 1 of nitrogen per hour were allowed to bubble continuously through the liquid colunm. Both liquid circulations were kept constant over the total extraction time. The aqueous salt solution was pumped in circulation at 5 ml/min and the isobutyl methyl ketone at 8 ml/min. The effluxing MBA-containing isobutyl methyl ketone phase was passed into the distillation vessel via the heated phase separator (80° C.). The isobutyl methyl ketone which was distilled off under gentle conditions was fed back into the circuit via the solvent reservoir. The MHA extracted remained in the distillation flask with isobutyl methyl ketone which had not been distilled off. After 90 hours, the extraction was ended and the yellow-coloured isobutyl methyl ketone from the distillation and the aqueous phase were weighed and analysed by HPLC. 4% of the MHA used was still found in the aqueous phase, 95% in the isobutyl methyl ketone. An ion chromatography analysis of the organic phase showed an ammonium content of <l 00 ppm. 

[0138] Extraction of (+)-camphor-I 0-sulphonic acid from a 10% (+)-camphor-I 0-sulphonic acid ammonium salt solu› tion with isobutyl methyl ketone in a specific rotational per› forator using an entraining gas as the stripping medium (in› ventive) 21.3 g (90 mmol, M=232.30 g/mol, with a content of 98%) of (+)-camphor-I 0-sulphonic acid were initially charged in 50 g of water and admixed with 6.5 ml of 32% aqueous ammonia solution (0.1 mo!). After stirring for 30 minutes, the excess ammonia and most of the water were drawn off from the clear colourless solution at 40° C. in a water-jet vacuum. The resulting white solid (39.8 g) was dissolved in 209.5 g of water. This 10% salt solution was initially charged in the rotational perforator (FIG. 1) and heated to 80° C. The solvent flask was initially charged with 500 g of isobutyl methyl ketone which were heated to boiling (internal temperature 115-117° C.). 6 1 of nitrogen per hour were passed continuously through the aqueous salt solution. After 66 hours, the extraction was ended and the pale-co› loured isobutyl methyl ketone and the aqueous phase were concentrated to dryness. 74% of the (+)-camphor-10-sul› phonic acid used was still found in the aqueous phase, 25% in the isobutyl methyl ketone. An ion chromatography analysis of the organic phase showed an ammonium content of <l 00 ppm. 

[0139] Extraction oftoluenephosphonic acid from a 10% toluenephosphonic acid ammonium salt solution with isobu› tyl methyl ketone in a specific rotational perforator using an 

## Example 10 

## Example 12 

## Example 13 

entraining gas as the stripping medium (inventive) 20.0 g (113.9 mmol, M=l 72.12 g/mol, with a content of 98%) of toluenephosphonic acid were initially charged in 50 g of water and admixed with 8.5 ml of 32% aqueous ammonia solution (0.13 mo!). After stirring for 30 minutes, the excess ammonia and most of the water were drawn off from the clear colourless solution at 40° C. in a water jet vacuum. The resulting oil (24.5 g) was dissolved in 190.9 g of water. This 10% salt solution was initially charged in the rotational per› forator (FIG. 1) and heated to 80° C. The solvent flask was initially charged with 500 g of isobutyl methyl ketone which were heated to boiling (internal temperature 115-117° C.). 6 1 of nitrogen per hour were passed continuously through the aqueous salt solution. After 23 hours, the extraction was ended and the pale-coloured isobutyl methyl ketone and the aqueous phase were concentrated to dryness. 56% of the toluenephosphonic acid used was still found in the aqueous phase, 43% in the isobutyl methyl ketone. An ion chromatog› raphy analysis of the organic phase showed an ammonium content of <l 00 ppm. 

1-19. (canceled) 

20. A process for converting an ammonium salt of an organic acid to a free organic acid, comprising: 

a) contacting an aqueous solution of the ammonium salt with an organic extractant; 

b) dissociating said ammonium salt at a temperature and pressure at which the aqueous solution and the extract› ant are in a liquid state; and 

c) introducing a stripping medium or entraining gas in order to remove NH$_{3 }$ from the aqueous solution and transfer at least a portion of the free organic acid formed to the organic extractant. 

21. The process of claim 20, wherein the conversion is carried out at a pressure of 0.01 bar to 20 bar. 

22. The process of claim 21, wherein the salt dissociation is performed at a temperature of 20° C. to 300° C. 

23. The process of claim 20, wherein: 

a) the conversion is carried out at a pressure of0.01 bar to 200 bar; 

b) salt dissociation is performed at a temperature of 5° C. to 300° C.; and 

c) the starting concentration of the ammonium salt of an organic acid in the aqueous solution used is in the range of from 90% by weight to 1 % by weight. 

24. The process of claim 23, wherein the extractant used is a sparingly water-miscible or entirely water-immiscible sol› vent. 

25. The process of claim 24, wherein the weight ratio of aqueous solution to organic extractant is from 1: 100 to 100: 1. 

26. The process 20, wherein the organic acid is selected from the group consisting of: monocarboxylic acid; dicar› boxylic acid; tricarboxylic acid; ascorbic acid; 

sulphonic acid; phosphonic acid; and hydroxycarboxylic acid. 

27. The process of claim 26, wherein, 

a) the conversion is carried out at a pressure of0.1 bar to 5 bar; 

b) salt dissociation is performed at a temperature of 50° C. to 130° C.; 

c) the starting concentration of the ammonium salt of an organic acid in the aqueous solution used is in the range of from 60% by weight to 10% by weight; 

