2-Chloro-5-fluorobenzoic acid

Light yellow powder

2-Chloro-5-fluorobenzoic acid serves as a precursor for metal complexes, where it is converted to the sodium salt with sodium hydroxide and reacted with copper(II) sulfate pentahydrate in aqueous medium to form copper(II) bis(2-chloro-5-fluorobenzoate). The resulting 2-chloro-5-fluorobenzoate anion acts as a ligand coordinating to Cu(II) centers in complex chains stabilized by C–H···π interactions, and constitutes the counter-anion in the crystal structure of [Co(phen)₂CO₃]₂(C₇H₃O₂FCl)Cl·11H₂O[1][2].

2-Chloro-5-fluorobenzoic acid is obtained via selective debromination of 4-bromo-2-chloro-5-fluorobenzoic acid under one-photon conditions[3].

[1] Singh, A., Sharma, R. P., Aree, T., Venugopalan, P. (2010). Weak C-H…F-C interactions in carboxylate anion binding: Synthesis, spectroscopic and X-ray structural studies of [Co(phen)2CO3]2 (C7H3O2FCl)Cl·11H2O and [Co(phen)2CO3](C7H3NO4Cl)·6H2O. Journal of Chemical Sciences, 122 5, 739–750. https://doi.org/10.1007/s12039-010-0062-3
[2] Sharma, R. P., Saini, A., Singh, S., Singh, A., Venugoplan, P., Starynowicz, P., Jezierska, J. (2011). Synthesis, characterization, single crystal X-ray structural studies and packing analyses of two novel copper(II) complexes: [Cu(2-Cl-5-FC7H3O2)2(β-picoline)2(H2O)2] and [Cu(en)2(H2O)2](2-Cl-5-FC7H3O2)2. Journal of Molecular Structure, 988 1, Pages 9-16. https://doi.org/10.1016/j.molstruc.2010.11.052
[3] Kerzig, C., Wenger, O. S. (2019). Reactivity control of a photocatalytic system by changing the light intensity. Chemical Science, 10(48), 11023–11029. https://doi.org/10.1039/c9sc04584h