4-chlorocatechol + O2 = 3-chloro-cis,cis-muconate + 2 H(+) 3,5-dichlorocatechol + O2 = (2E,4E)-2,4-dichloromuconate + 2 H(+) Binds 1 Fe(3+) ion per subunit. Belongs to the intradiol ring-cleavage dioxygenase family.