US 8,785,686 B2  24  23  percent, based on the total weight of the wash solvent, of a  wash diluent comprising hexane, heptane, decane, meth› ylcyclohexane, benzene, toluene, xylene, isoparaffinic  mixed hydrocarbons having a boiling range between 90  and 325°  C., or a combination thereof; and about Oto about  20 weight percent of a wash modifier comprising 2-ethyl› hexanoic acid, !auric acid, bis(2-ethylhexyl)hydrogen  phosphate, 2-ethylhexanol, 2-ethylbutanol, n-hexanol,  n-octanol, n-decanol, or a combination thereof, to form a  washed aqueous raffinate phase and an organic wash  extract phase, wherein the weight ratio of the wash solvent  to the aqueous raffinate phase is about 0.1: 1 to about 1: 1;  Embodiment 32 is a process that includes the features of  any one of embodiments 30 and 31, in which the acid catalyst  comprises methanetrisulfonic acid.  Embodiment 33 is a process that includes the features of  any one of embodiments 30-32, in which the tertiary amine  comprises tris(2-ethylhexyl)amine; the modifier comprises  2-ethylhexanoic acid; the diluent comprises hexane, heptane,  decane, or a combination thereof; the wash solvent comprises  hexane, heptane, decane, isoparaffinic mixed hydrocarbons  having a boiling range between 90 and 325°  C., or a combi› nation thereof; the wash modifier comprises 2-ethylhexanoic  acid, n-hexanol, n-decanol, or a combination thereof; and the  weight ratio of the modifier to the tertiary amine is about 2: 1  to about 4:1.  Embodiment 34 is a process that includes the features of  any one of embodiments 30-33, in which the aqueous form› aldehyde solution of step (D) comprises about 40 to about 55  weight percent formaldehyde and the aqueous formaldehyde  extract of step (D) is passed to step (A).  The principles laid out in the instant invention are further  illustrated by the following examples.  Glycolic acid solutions and extraction samples were ana› lyzed by liquid chromatography. Quantitation of analytes  comprising glycolic acid, glycolate oligomers, and related  species was performed using ion-exclusion chromatography  after samples were subjected to acid hydrolysis in aqueous  25% v/v H$_{2}$ SO$_{4 }$ at 80°  C. for 30 minutes. The analytes were  separated on a Hamilton PRP X300 colunm using a 10 mM  H$_{3}$PO$_{4 }$ mobile phase with a 1-20% v/v acetonitrile gradient.  The eluting components were monitored using a UV detector  set at 210 nm and their concentrations calculated based on  calibration using external standards. Formaldehyde was  determined by liquid chromatographic separation of the 2,4- dinitrophenylhydrazone derivative of formaldehyde and its  subsequent detection by UV at 360 nm. The same acid  hydrolysate from the procedure above was reacted with dini› trophenylhydrazine, then analyzed using a Phenomenex Luna  CS colunm using a 1: 1 water:acetonitrile mobile phase under  isocratic conditions. The formaldehyde concentration was  calculated based on calibration using external standards.  Reactor effluent and extraction samples also were analyzed  for sulfur using a wavelength dispersive x-ray fluorescence  (WDXRF)  semi-quantitative  application  called  UNI- QUANT™ (UQ). UQ affords standardless XRF analysis of  samples. The data were mathematically corrected for matrix  Preparation of Aqueous Glycolic Acid Solutions-Hydro› carboxylation reactor effluents were prepared for subsequent  extraction experiments in the following manner for Examples  1-4: A mixture comprising formaldehyde, water, glycolic  acid, and acid catalyst was fed continuously to a high pressure  zirconium autoclave, nominally 125 mL volume, fitted with a  hollow shaft Rushton turbine impeller (for gas introduction  and dispersion), baffles, thermo well, gas inlet tube, and sip  tube to maintain liquid level at approximately 90 mL and to  provide an exit for product effluent. The autoclave was heated  electrically by a band heater, with temperature control pro- vided by feedback via a K-type thermocouple in the autoclave  thermo well. Pure carbon monoxide gas (>99 .9%) was fed to  the autoclave via a Brooks flow controller. Reactor effluent  passed through zirconium tubing, maintained at 60°  C., an  automatic pressure control valve, and into a Hastelloy collec› tion vessel (I liter), also maintained at 60°  C. The collection  vessel was drained every six hours and analyzed by liquid  chromatography, gas chromatography, and X-ray sulfur  For all extraction examples, the molar selectivity for the  tertiary amine-containing phase (i.e., extraction solvent) for  sulfuric acid (H$_{2}$ SO$_{4}$ )  over glycolic acid (GA) is defined as  follows:  Extractor samples were diluted in isopropyl alcohol to  minimize matrix effects and analyzed quantitatively using  WDXRF. The WDXRF calibrations were performed using  serial dilutions of stock standards prepared wt./wt. and certi› fied using ICP-OES. Instrument conditions for sulfur analysis  were: Line,  Ka;  kV, 50; mA, 60; Filter, none; Collimator  Spacing (mm), 700; Crystal, Graphite; Peak Angle (2q),  106.4608; --offset, 2.6696; Detector, flow; PHD Lower, 27;  PHD Upper, 75; Collimator Mask (mm), 30; -Offset  time (s), 10; Peak time (s), 50.  differences between calibration standards and samples as  well as absorption and enhancement effects; i.e., inter-ele› ment effects. Instrument conditions for sulfur analysis were:  Line,  Ka;  kV, 40; mA, 60; Filter, none; Collimator Spacing  (mm), 150; Crystal, Ge III-C; Peak Angle (2q), 110.6712;  Detector, flow; PHD Lower, 35; PHD Upper, 70; Collimator  Mask (mm), 30; Peak time (s), 30.  (F) separating the washed aqueous raffinate and organic wash  extract phases; and  ( G) combining the organic wash extract phase with the extrac› tion solvent of step (B) or with the organic extract phase of  step (C).  EXAMPLES  General  Examples 1-4  Throughout the examples, the following abbreviations are  used in the Tables:  (Moles H2 SO4 in amine phase) x  (Moles  GA  in aqueous  GA  Phase)  Molar Selectivity= (Moles H2SO4 in  aq. GA  phase) x  (Moles H 2 SO 4  in amine phase)  HFr=formaldehyde  GA=glycolic acid and oligomers  HOFr=formic acid  DGA=diglycolic acid  MAA=methoxyacetic acid  TfOH=trifluoromethanesulfonic acid or triflic acid  PFOA-H=perfluorooctanoic acid  TEHA=tris(2-ethylhexyl)amine  2-EHA=2-ethylhexanoic acid  DEHPA=bis(2-ethylhexyl)hydrogen phosphate  MTSA =methanetrisulfonic acid  MDSA=methanedisulfonic acid  MMSA=methylsulfonylmethanesulfonic acid  BMMSA=bis(methylsulfonyl)methanesulfonic acid 