US 8,709,376 B2  38  37  TABLE 16-continued  TABLE 17  Examples 43-48  Back Extractions of Sulfuric Acid-Rich Solvents in  Continuous Column  Continuous Wash ofRaffinate from Forward  Extraction  Examples 41-42  TABLE 18  TABLE 19  Feed Conditions for Forward Extractions of Sulfuric  Acid in Continuous Karr Column Operation  Solv.  Solv.  Wash  Wash  Flow  Solvent  Comp.  Flow  Wash  Comp  Ex.  g/min  Location  TEHA  2-EHA  Heptane mL/min  Location  Heptane  36  37  38  39  40  15.2  F5  10.11% 36.49% 53.40%  none  15.2  F4  10.78% 37.39% 51.83%  6.9  15.2  F4  9.99% 36.96% 53.05%  6.9  15.2  F5  10.00% 36.13% 53.87%  none  11.4  F5  10.73% 36.50% 52.77%  none  F5  F5  100.0%  100.0%  Ex.  36  37  38  39  40  Results of Forward Extractions of Sulfuric Acid in  Continuous Karr Colwnn O12eration  TEHA/H$_{2}$SO$_{4 }$ EHA/TEHA  molar ratio  molar ratio  H$_{2}$SO$_{4 }$ Amine Heptane  0.94  3.61  98.6%  97.7%  100.0%  1.14  3.47  99.3%  98.6%  100.0%  1.08  3.70  97.8%  98.4%  100.0%  0.76  3.61  80.3%  98.9%  100.0%  3.26  3.40  93.4%  90.0%  100.0%  2-EHA  99.3%  99.6%  98.8%  99.0%  97.0%  Glycolic  Oligomers  99.1%  98.9%  98.8%  99.0%  99.5%  Ex.  41  42  T, CC.  45  70  Agit  Rate  Strokes/  min  200  310  Feed Conditions for Wash Extractions ofRaffinates  from Continuous Forward Extractions  Mass  W/F Ratio  0.52  0.51  Feed  Flow  g/min  13.3  20.0  Feed  Location  Fl  Fl  wt%  wt%  TEHA  2-EHA  0.17%  0.46%  0.62%  0.8%  Wash Flow  Wash  g/min  Location  6.9  6.9  F5  F5  Ex.  41  42  Results ofWash Extractions ofRaffinates  from Continuous Forward Extractions  Amine  91.6%  87.0%  Heptane  99.97%  99.9%  2-EHA  93.1%  82.7%  For example 41, the sulfuric acid-lean raffinate of Example  36, comprising glycolic acid, glycolate oligomers, and water  was contacted continuously with a heptane wash solvent as  the continuous phase in the Karr colunm described above to  remove additional 2-ethylhexanoic acid and TEHA. Simi› larly for Example 42, the raffinate from Example 39 was  contacted with heptane in the continuous colunm to remove  additional 2-ethylhexanoic acid and TEHA. Feed composi› tions, flow rates, feed locations, and temperature of the wash  experiments are summarized in Table 18. In each experiment,  the colunm reached steady state within an hour and was run  continuously for six to eight hours, with sampling occurring  every one to two hours. Averaged recoveries ofTEHA, 2-eth› y lhexanoic acid, and heptane to wash extract product over the  time of steady state operation are given in Table 19.  Sulfuric acid-rich extracts compnsmg sulfuric acid,  TEHA, 2-ethylhexanoic acid, and heptane derived from the  forward extraction of hydrocarboxylation effluents were fed  to the continuous Karr colunm at a temperature of 70°  C. as  described above and contacted with an aqueous formalde- hyde extraction solvent ( continuous phase). The sulfuric  acid-rich extracts were introduced to the Karr colunm at  location F5 and the aqueous formaldehyde solvent was intro› duced at location Fl. Feed and solvent compositions, and  flow rates of the forward extraction experiments are summa- rized in Table 20. In each experiment, the colurmi reached  steady state within an hour and was run continuously for six  to eight hours, with sampling occurring every one to two  hours. Averaged recoveries of TEHA, 2-ethylhexanoic acid,  and heptane to the raffinate product, and glycolic acid and  sulfuric acid to the formaldehyde extract product over the  time of steady state operation are given in Table 21. 