is ethylenediaminetetraacetic acid the reaction of the alkylenediaminetetraacetic acid with formamide is preferably performed neat but can also be performed in a liquid diluent which is inert to the instant reactants suitable diluents include n methylpyrolidinone n n dimethylformamide dimethyl sulfoxide and bisethers of polyalkylene oxides such as diethylene glycol methyl ether and dipropylene glycol methyl ether the reactants are conveniently employed in their stoichiometric ratio i e two moles of formamide for each mole of alkylenediaminetetraacetic acid however in one preferred embodiment an excess of formamide is employed to serve as a solvent the reaction temperature is advantageously high enough to distill water and other by products produced in the formation of the diimide generally temperatures of at least about 100 u00b0 c afford convenient rates of reaction the progress of the reaction can be monitored by the quantity of the by products recovered overhead the pressure during the reaction is not critical but sub atmospheric pressures are preferred the diimide product can be conveniently recovered from the reaction mixture by distillation to remove unreacted starting materials and any more volatile products overhead the crude diimide in the undistilled residue can be purified by recrystallization in a manner known in the art methanol is the preferred solvent for recrystallization the diimide is reacted in a liquid medium with a base capable of abstracting a proton from each of the nitrogen groups of the diimide preferred bases include alkali metal or alkaline.