US 8,785,686 B2  50  49  TABLE 23-continued  TABLE25  TABLE 23  TABLE 26  TABLE24  that MMSA (2.56 g, 40.7 wt% assay, 0.006 mole) and water  (0 g, total water is 0.1 mole from other starting materials)  were added to the zirconium autoclave. To this was added  HCHO (6.3 g, 95 wt% assay, 0.20 mole) and GA ( 40 g, 0.40  mole). The concentration ofMMSA at the start of the reaction  was 2.4 weight percent, based on the total weight of the  starting reaction mixture. The pressure and temperature were  maintained for 4 hours and samples were taken at approxi› mately 0, 30, 60, 90, 120, 150, 180, and 240 minutes. The  yield of GA, the reaction rate, and concentration of acid  catalyst in the final product mixture are shown in Table 23.  Rate of Hydrocarboxylation of Formaldehyde Using  BMMSA-The procedure of Example 54 was followed  except that BMMSA (1.19 g, 85 wt% assay, 0.004 mole) and  water (4.53 g, 0.28 mole) were added to the zirconium auto› clave. To this was added HCHO (6.3 g, 95 wt% assay, 0.20  mole) and GA (30.4 g, 0.40 mole). The concentration of  BMMSA at the start of the reaction was 2.4 weight percent,  based on the total weight of the starting reaction mixture. The  pressure and temperature were maintained for 4 hours and  samples were taken at approximately 0, 30, 60, 90, 120, 150,  180, and 240 minutes. The yield of GA, the reaction rate, and  concentration of acid catalyst in the final product mixture are  shown in Table 23.  The hydrocarboxylation experiments of Comparative  Example 54 and Examples 55-58 shown in Table 23 illustrate  the effect of the various sulfonated acids on the yield and rate  of glycolic acid formation in comparison to the H$_{2}$ SO$_{4}$ -cata- lyzed reaction under the same reaction and sampling condi› tions. The data of Table 23 show higher yields and reaction  rates for the MTSA-catalyzed reaction in comparison to the  H$_{2}$ SO$_{4}$ -catalyzed process. The selectivity to glycolic acid  was not reported for these experiments because competing  reactions in the batch autoclave studies did not permit a  representative calculation of selectivity.  Conversion, space-time yield, and selectivity to end prod› ucts based on reacted formaldehyde are shown in Table 26. As  noted above, glycolic acid oligomers, esters, and other forms  of glycolic acid were hydrolyzed to the corresponding acids  prior to analysis by HPLC. Also, methanol that was present as  methyl glycolate was converted to and reported as free metha- nol by the analytical method described above.  Continuous Hydrocarboxylation of Formaldehyde to Gly› colic Acid With MTSA-Examples 59-61 illustrate the effect  of flow rate, temperature, pressure, and catalyst level on the  hydrocarboxylation of formaldehyde with MTSA as the cata› lyst. The composition and flow rate of the feed to the reactor  is given in Table 24. Overall feed molar flow ratios of GA  relative to formaldehyde are presented in Table 25, along with  reaction temperature, pressure, and residence time.  Examples 59-61  Example 58  Relative Rate of Glycolic Acid Formation in Batch Reactions  Rate  Yield of GA  (mmol/g  Wt% Acid Cat. in  Example  Acid  (%)  new GA)  Product Mixture  57  MMSA  16%  1.0  2.7  58  BMMSA  9%  0.6  4.0  Feed Rates and Composition for the Continuous  Hydrocarboxylation ofHFr  Feed Composition, wt%  Example  Feed  g/min  Formaldehyde  water  GA  MTSA  59  60  61  1.01  1.68  2.35  13.0  13.0  13.0  17.2  17.2  17.2  66.0  66.0  66.0  3.8  3.8  3.8  Relative Rate of Glycolic Acid Formation in Batch Reactions  Rate  Yield of GA  (mmol/g  Wt% Acid Cat. in  Example  Acid  (%)  new GA)  Product Mixture  C-54  H$_{2}$SO$_{4 }$ 15%  1.0  1.6  55  MTSA  27%  1.6  3.8  56  MDSA  18%  1.0  2.7  Example  59  60  61  Overall Feed Ratios and Reaction Conditions  for the Continuous Hydrocarboxylation ofHFr  Temper- Pressure  Feed Molar Ratio  ature  (bars  HFr  H$_{2}$O  GA  MTSA  (" c.)  gauge)  1.0  2.2  2.0  0.034  190  178.5  1.0  2.2  2.0  0.034  205  179.1  1.0  2.2  2.0  0.034  205  179.4  Res  Time  (min)  104  63  45  Results for Continuous Hydrocarboxylation ofHFr Using MTSA  Space-Time  Wt%Acid  %HFr  Molar Selectivi!Y, %  Yield  Cat. in Prod.  Example  Conv.  GA  HOFr DGA MAA MeOH  (gmol/1-hr)  Mixture  59  93  87.8%  4.7  2.1  1.7  3.8  2.0  3.5  60  94  89.2%  3.0  4.0  1.7  2.2  3.5  3.5  61  93  88.5%  3.5  3.5  2.0  2.4  4.8  3.5 