9-Phenyl 5,6-dimethyl-nona-2,4,6,8-tetraeonic acid compounds

A compound of the formula ##STR16## wherein R.sub.1 and R.sub.2 are lower alkyl;

• R.sub.3 is hydrogen, lower alkyl, lower alkoxy, lower alkenyloxy, nitro, halo, amino, lower alkylamino, lower alkanoylamino R.sub.4 is hydrogen, lower alkyl, lower alkenyl, lower alkoxy, lower alkenyloxy, nitro, lower alkanoyloxy, amino, lower alkylamino R.sub.5 is hydrogen, lower alkyl, lower alkenyl, lower alkoxy, lower alkenyloxy, nitro, halo, amino, lower alkanoylamino, lower alkylamino with the proviso that at least one of R.sub.3, R.sub.4 and R.sub.5 is other than hydrogen;
• with the further proviso that when R.sub.3 or R.sub.5 is halogen, R.sub.4 is other than alkoxy;
• and R.sub.6 is carboxyl and pharmaceutically acceptable salts thereof.