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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. 

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## Example 58 

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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. 

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. 

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## Examples 59-61 

