Methyl oxalate could be produced through the following synthetic routes.

In a 500-cc. Pyrex flask, fitted with a cork which loosely carries a glass mechanical stirrer and a separatory funnel, are placed 90 g. (1 mole) of anhydrous oxalic acid and 100 cc. (79 g., 2.5 moles) of methanol. Then, while the mixture is rapidly stirred, 35 cc. of pure concentrated sulfuric acid is slowly added through the separatory funnel. The mixture is heated, if necessary, nearly to boiling, then filtered as rapidly as possible through a 15-cm. filter paper placed in a slightly heated glass funnel, the filtrate being collected in a 500-cc. wide-mouthed Erlenmeyer flask. The first flask is rinsed with 40 cc. of hot methanol, which is poured through the filter paper. After twenty-four hours at 15°the crystals are filtered with suction, sucked as dry as possible, pressed between filter paper, and air-dried for a few minutes. The filtrate, after cooling to about -10°, is filtered rapidly and the product dried as before. A total of 100–115 g. of material, slightly moist with sulfuric acid and melting at 50–52°, is obtained.

For purification, the crude product is dissolved in 100 cc. of redistilled methanol, filtered through a warm funnel, and allowed to crystallize. After several hours the crystals are filtered, and the filtrate is chilled and filtered as before. A total of 80–90 g. (68–76 per cent of the theoretical amount) of methyl oxalate, melting at 52.5–53.5°, is obtained.