acid mixture comprising about 70 to about 90 weight per› cent glycolic acid, based on the total weight of the aqueous  glycolic acid mixture, and about 1 to about 10 weight  percent of the acid catalyst;  (B) extracting the aqueous glycolic acid mixture with an  extraction solvent, comprising  (i) about 5 to about 45 weight percent, based on the total  weight of the extraction solvent, of a tertiary amine  comprising tris(2-ethylhexyl)amine, tris(2-ethylbutyl)  amine,  trioctylamine,  triisooctylamine,  triisodecyl  amine, tridodecylamine, tridecylamine, dioctyldecy› lamine, didecyloctylamine, or a combination thereof;  (ii) about 5 to about 45 weight percent, based on the total  weight of the extraction solvent, of a modifier compris- ing 2-ethylhexanoic acid, !auric acid, bis(2-ethylhexyl)  hydrogen phosphate, perfluorooctanoic acid, or a com› bination thereof, wherein the weight ratio of the modifier  to the tertiary amine is about  1:  1 to about 5: 1; and  (iii) about 10 to about 90 weight percent of a diluent, based  on the total weight of the extraction solvent, comprising  hexane, heptane, decane, methylcyclohexane, benzene,  toluene, xylene, isoparaffinic mixed hydrocarbons hav› ing a boiling range between 90 and 325°  C., or a com› bination thereof;  to form an aqueous raffinate phase comprising a major  amount of the glycolic acid contained in the aqueous  glycolic acid mixture and an organic extract phase com› prising a major amount of the acid catalyst contained in  the aqueous glycolic acid mixture;  (C) separating the aqueous raffinate and organic extract  phases; and  (D) extracting the organic extract phase from step (  C) with an  aqueous formaldehyde solution, comprising about 35 to  about 85 weight percent formaldehyde, based on the total  weight of the aqueous formaldehyde solution, to form an  aqueous formaldehyde extract comprising a major amount  of the acid catalyst contained in the organic extract phase  from step  (C) and an organic raffinate phase comprising a  minor amount of the acid catalyst contained in the organic  extract phase.  (i) about 50 to about 95 weight percent glycolic acid, based  on the total weight of the aqueous glycolic acid mixture,  and  (A) extracting an aqueous glycolic acid mixture, comprising 55  (ii) about 0.2 to about 12 weight percent, based on the total  weight of the aqueous glycolic acid mixture, of an acid 60  catalyst comprising sulfuric acid, an alkyl sulfonic acid  containing from 1 to 5 carbon atoms, a fluoroalkyl sul› fonic acid containing from 1 to 5 carbon atoms, or a  combination thereof;  (i) about 5 to about 45 weight percent, based on the total  weight of the extraction solvent, of at least one tertiary  (C) extracting the organic extract phase from step (B) with an  aqueous formaldehyde solution to form an aqueous form› aldehyde extract comprising a major amount of the acid  catalyst contained in the organic extract phase from step  (B) and an organic raffinate phase comprising a minor  amount of the acid catalyst contained in the organic extract  phase.  (B) separating the aqueous raffinate and organic extract  phases; and  to form an aqueous raffinate phase comprising a major  amount of the glycolic acid contained in the aqueous  glycolic acid mixture and an organic extract phase com› prising a major amount of the acid catalyst contained in  the aqueous glycolic acid mixture;  (iii) about 10 to about 90 weight percent of at least one  diluent comprising carbon dioxide, an aliphatic hydro› carbon containing from 3 to 25 carbon atoms, an aro› matic hydrocarbon containing 6 to 25 carbon atom, a  halogenated hydrocarbon containing 6 to 25 carbon  atoms, or a combination thereof;  (ii) about 5 to about 45 weight percent of at least one  modifier comprising an aliphatic carboxylic acid con› taining from 5 to 16 carbon atoms, a fluoroalkyl car› boxylic acid containing 5 to 16 carbon atoms, an orga› nophosphorus acid containing from 5 to 16 carbon  atoms, or a combination thereof; and  It is understood that the above process can include the various  embodiments of the hydrocarboxylation process, formalde› hyde and carbon monoxide reactants, aqueous glycolic acid  mixture, the sulfonic acid catalysts, reactor formats and con› figurations, reaction conditions of time, temperature, and  pressures, extraction solvents, tertiary amines, modifiers,  diluents, and wash steps as described hereinabove and in any  combination. For example, as described previously, the acid  catalyst can comprise methanetrisulfonic acid.  The invention also includes the following embodiments  1-34 set forth below. Embodiment 1 is a process for recover› ing an acid catalyst from aqueous glycolic acid, comprising:  with an extraction solvent, comprising  Embodiment 7 is a process that includes the features of any  one of embodiments 1-6, in which the aqueous formaldehyde  solution comprises about 35 to about 85 weight percent form› aldehyde, the aqueous formaldehyde extract comprises about  0.5 to about 10 weight percent, based on the total weight of  the aqueous formaldehyde extract, of the acid catalyst, and  the weight ratio of the aqueous formaldehyde solution to the  organic extract phase is about 0.1: 1 to about 1: 1.  Embodiment 6 is a process that includes the features of any  one of embodiments 1-5, in which the diluent comprises  pentane, hexane, heptane, decane, methylcyclohexane, meth› ylene chloride, chlorobenzene, dichlorobenzene, 1,2-dichlo› roethane, benzene, toluene, xylene, or a combination thereof.  Embodiment 5 is a process that includes the features of any  one of embodiments 1-4, in which the modifier comprises  n-pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic  acid, hexanoic acid, 2-ethylbutanoic acid, heptanoic acid,  octanoic  acid,  2-ethylhexanoic  acid,  pelargonic  acid,  nonanoic acid, decanoic acid, !auric acid, palmitic acid, bis  (2-ethylhexyl)hydrogen phosphate, perfluorooctanoic acid,  or a combination thereof.  Embodiment 4 is a process that includes the features of any  one of embodiments 1-3, in which the tertiary amine com› prises tris(2-ethylhexyl)amine, tris(2-ethylbutyl)amine, trio› ctylamine, triisooctylamine, triisodecyl amine, tridodecy- !amine,  tridecylamine,  dioctyldecylamine,  didecyloctylamine, or a combination thereof.  Embodiment 3 is a process that includes the features of any  one of embodiments 1 and 2, in which the acid catalyst  comprises sulfuric acid, trifluoromethanesulfonic acid, meth› anesulfonic acid, methanedisulfonic acid, methanetrisulfonic  acid, bis(methylsulfonyl)methanesulfonic acid, 1,1,2,2-tet- rafluoroethanesulfonic acid, or a combination thereof.  Embodiment 2 is a process that includes the features of  embodiment 1 in which the aqueous glycolic acid mixture  comprises about 70 to about 90 weight percent glycolic acid  and is produced by contacting aqueous formaldehyde with  carbon monoxide in the presence of an acid catalyst.  amine containing from 12 to 40 carbon atoms, at least  one onium carboxylate compound, or a combination  thereof;  US 8,785,686 B2  18  17 