A process for preparing butanetetracarboxylic acid derivatives as product of
value
I by coupled electrosynthesis which comprises cathodically reducing a compound
selected from the group consisting of maleic esters, maleic ester derivatives,
fumaric esters and fumaric ester derivatives where at least one hydrogen atom in
positions 2 and 3 may be replaced by inert groups and obtaining a product of value
II at the node.
