The following examples illustrate the hydrocarboxylation  of MDA in acetic acid catalyzed by various strongly acidic  homogeneous catalysts. MDA was prepared as described  above in Example 66.  To a Hastelloy 276C 300 mL autoclave equipped with a  liquid sampling loop and a high pressure addition funnel was  added acetic acid (60.05 g, 1.0 mo!), water (9.0 g, 0.5 mo!),  and trifluoromethanesulfonic acid catalyst (0.375 g, 2.5  mmol). The autoclave was heated with a heating block, with  temperature control provided by feedback via a thermocouple  1  in the autoclave thermowell. Pure carbon monoxide gas  (>99.9%) was fed to the autoclave via a high pressure regu› lator. The MDA (66.26 g, 0.5 mo!) was added to the addition 15  funnel (blowcase). The autoclave was sealed, flushed with  CO and heated to 140°  C. under 100 psig carbon monoxide.  The addition funnel containing the MDA was heated to 100°  C. Upon reaching 140°  C. in the autoclave, the MDA was  charged to the autoclave by pressurizing the addition funnel.  Immediately upon completing the liquid addition, a sample  was removed from the autoclave (time zero) and the pressure  was adjusted to 1000 psig CO. The temperature and pressure  were maintained using pure carbon monoxide for the duration  of the 4 hour reaction. Samples were removed from the auto- 25  clave at 15 min, 30min, 45 min, 60min, 120min, 180minand  240 min. The samples were analyzed by GC and HPLC. Final  conversion and selectivity is given in Table 14.  The continuous hydrocarboxylation was carried out using  a reactor system containing Hastelloy 276C autoclave (125  ml nominal volume) and associated feed and product storage  equipment. The high pressure autoclave was fitted with a  hollow shaft Rushton turbine impeller (for gas introduction  and dispersion), baffles, thermowell, 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  thermowell.  US 8,927,766 B2  42  41  Example 97  Example 92  Examples 93-96  TABLE 14  TABLE 15  Pure carbon monoxide gas (>99.9%) was fed to the auto› clave via a high pressure flow controller. The gas entered the  body of the autoclave via groves in the impeller bearings. The  off gas flow rate was monitored by a  dry  bubble-type flow  meter. The flow rates of the two liquid feeds were controlled  to a precision of 0.001 ml/min with double-barreled 500 ml  high-precision syringe pumps connected to stirred feed ves› sels.  Reactor effluent passed through heated Hastelloy tubing,  an automatic pressure control valve (research control valve),  and into a 1.0 L heatable Hastelloy collection vessel. The  effluent collection vessel was fitted with a chilled coiled con› denser. The gas outlet from the effluent tank was connected to  a manual back pressure regulator to maintain vessel pressure  at 40-100 psig. Temperatures, pressures, and other relevant  system parameters were recorded automatically by a distrib- uted control system.  Example 92 was repeated except the acid catalyst and  amount were as given in Table 14. 2.5 mmol of acid catalyst  was used in each case. The final MDA conversions and selec› tivities are given in Table 14.  Feed 1 (0.4 g/min) and Feed 2 (0.39 g/min), having the  composition given in Table 15 were fed to the reactor. Carbon  monoxide was fed at a rate of998 SCCM as noted in Table 16.  The reaction was run at a pressure of 1500 psig and a tem› perature ofl 70°  C. with a residence time of85 minutes. Table  16 also gives feed molar ratios and the source of formalde› hyde. For Example 107 the source was trioxane.  Samples of the hydrocarboxylationreaction were analyzed  by HPLC. Conversion, space-time yield, and selectivity of  reacted formaldehyde to end products are summarized in  Table 17. Any glycolic acid fed was subtracted out for con› version and yield calculations. Methanol was present as free  methanol, methyl glycolate, and methyl valerate, and was  converted to free methanol, glycolic acid, and valeric acid by  the analytical method.  The following examples illustrate the effect of feed water  content, temperature, pressure, and catalyst level on the  hydrocarboxylation of trioxane or paraformaldehyde with  valeric acid and glycolic acid as solvents/reactants and triflic  acid as catalyst.  Example 97 was repeated with the liquid feeds given in  Table 15, the carbon monoxide flow rate, source of formal- dehyde, feed molar ratios, pressure, temperature, residence  time given in Table 16. Conversion, space-time yield, and  selectivity of reacted formaldehyde to end products are sum› marized in Table 17.  Examples 98-143  Ex.  92  93  94  95  96  Hydrocarboxylation of MDA in Acetic Acid  with a Homogeneous Strong Acid Catalyst.  MDA  Catalyst  Conver- Catalyst  charge (g)  sion  trifluoromethanesulfonic acid  0.375  99  tetrafluoroethanesulfonic acid  0.455  96  bis( trifluoromethane )sulfony !amide  0.70  99  nonafluorobutanesulfonic acid  0.75  99  sulfuric acid  0.256  81  MDA  Selec- tivity  96  96  95  95  53  Ex#  97  98  99  100  101  102  103  Feed 1 and Feed 2: Rates and Compositions  Feed 1  Feed 1, mass%  Feed 2  Feed 2 mass%  g/min  F0  AS  G1  water  Triflic  g/min  AS  Triflic  0.40  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00  0.39  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00  0.39  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00  0.39  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00  0.39  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00  0.39  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00  0.39  21.1  71.9  0.0  3.8  3.2  0.39  100.00  0.00 