Patent ID: 6909016

Claim:
A process for preparing a butanetetracarboxylic acid derivative as product I by coupled electrosynthesis in an electrochemical cell, which comprises (1) cathodically reducing a compound selected from the group consisting of maleic esters, maleic ester derivatives, fumaric esters and fumaric ester derivatives, wherein the maleic ester- and fumaric ester-derivatives are selected from the group consisting of methyl-, cyano-, hydroxymethyl- and methoxy-substituted derivatives, where at least one hydrogen atom in positions 2 and 3 may be replaced by inert groups, and obtaining an isolatable product II at the anode, isolatable wherein the product II is selected from the group consisting of acetals of aromatic aldehydes, methoxylated heterocycles, aromatics and olefins, methoxylated amides, α-hydroxyketals, α-hydroxyacetals, carboxylic acids and carboxylic esters, and wherein the electrode material comprises materials based on carbon, and (2) working up and separating the butane tetracarboxylic acid derivative from the rest of the electrolysis solution.