3,5-dichlorocatechol + O2 = (2E,4E)-2,4-dichloromuconate + 2 H(+) Binds 1 Fe(3+) ion per subunit. Xenobiotic degradation; 2-(2,4-dichlorophenoxy)propanoate degradation. By chemostress caused by the herbicide 2,4-dichlorophenoxypropionic acid (2,4-DCPP) and its metabolites. Belongs to the intradiol ring-cleavage dioxygenase family.