| 摘要 |
Oxalic esters are hydrogenated at an elevated temperature not exceeding about 250 DEG C., suitably at about 40 - 250 DEG C., with gaseous hydrogen in the presence of a Ru or Ni catalyst. At the lower end of the temperature range the hydrogenation is selective to the glycolic ester whilst at the upper end it is selective to ethylene glycol. In the intermediate range, at about 130 - 150 DEG C., both products may appear, the precise transition temperature range depending also on other parameters such as the nature of the catalyst and the hydrogen pressure. The hydrogenation may be carried out with the oxalic ester in the gas or in the liquid phase. |
