PURPOSE: In the preparation of a oxalic diester by subjecting a nitrite, alcohol, carbon monoxide, and oxygen to a contact reaction under pressure in the presence of Pd catalyst, to obtain the titled compound advantageously, by recovering an alcohol from the reaction solution, distilling the alcohol in the presence of copper, etc., and circulating the alcohol as the raw material for use.
CONSTITUTION: After a nitrite, an alcohol, carbon dioxide, and oxygen are subjected to contact reaction under pressure in the presence of a Pd catalyst conventionally, the unreacted raw material and by-products are removed from the reaction solution to give the titled compound. The by-products, e.g., a separated formic ester, etc. is decomposed into an alcohol. This alcohol and unreacted alcohol are recovered and distilled in the presence of copper or a copper compound, to give a purified alcohol which is circulated as the raw material of the above-mentioned reaction for use. The titled compound is thus obtained advantageously for a long time without reduction in the reaction rate and requiring the recovery of the catalyst.
EFFECT: Reaction inhibiting substances in the alcohol can be removed by a simple operation.
YAMASHITA MASAYOSHI
YAMANAKA EIJI
UCHIUMI SHINICHIROU
IWAYAMA AKIRA
KURAHASHI MASARU
