Preferentially converts 3-chlorocatechol and 3,5-dichlorocatechol as opposed to other chlorinated catechols. Retains diminished activity toward non-chlorinated substrates. 3-chlorocatechol + O2 = (2E,4Z)-2-chloromuconate + 2 H(+) 3,5-dichlorocatechol + O2 = (2E,4E)-2,4-dichloromuconate + 2 H(+) Binds 1 Fe(3+) ion per subunit. Aromatic compound metabolism; 3-chlorocatechol degradation. Belongs to the intradiol ring-cleavage dioxygenase family.