(2R*,3R*,11R*,12R*)-1,4,7,10,13,16-Hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid 1,4,7,10,13,16-Hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid, (2R*,3R*,11R*,12R*)- 119719-58-3 18-Crown-6 2,3,11,12-tetracarboxylic acid 18-Crown-6 4COOH