4-Chlorosalicylic acid (4-Chloro-2-hydroxybenzoic acid 4-chloro salicylic acid) was used in sensitive spectrofluorometric determination of terbium in mixed rare earths and preparation of poly(4-chlorosalicylic acid-formaldehyde) via condensation with formaldehyde 4-Chlorosalicylic acid is a pharmaceutical intermediate Inhibits monophenolase and diphenolase activity with IC50s of 1 89 mM and 1 10 mM Potent antimicrobial activity Against E coli with the MIC of 250 g/mL and with the MBC of 500 g/mL