p-phenylenediamine-N,N,N',N'-tetraacetate, p-phenylenediamine-N,N,N',N'-tetraacetic acid, 2-({4-[bis(carboxymethyl)amino]phenyl}(carboxymethyl)amino)acetic acid, p-phenylenedimethylene-di-malonic acid tetraethyl ester, p-Phenylendimethylen-di-malonsaeure-tetraaethylester, Terephthalyliden-tetracarbonsaeure-tetraethylester, p-Phenylen-bis-(methylen-malonsaeurediethylester), tetraethyl 2,2'-(1,4-phenylene(bis(methanylylidene)))dimalonate, p-phenylene-1,4-diyldiamino-tetra-acetic acid, 1,4-diaminobenzene tetraacetic acid, p-Phenylen-1,4-diyldiamino-tetra-essigsaeure, N.N.N'.N'-Tetrakis-carboxymethyl-p-phenylendiamin, 1,4-Bis-<2,2-diethoxycarbonyl-vinyl>-benzol, tetraethyl 2,2'-(1,4-phenylenedimethylidyne)bismalonate