Abstract
The asymmetric unit of a second polymorph of the title compound, C(9)H(4)F(6)O(2), contains five independent mol-ecules, which form hydrogen-bonded O-H⋯O dimers about inversion centers. The most significant structural difference between this structure and that of the first polymorph [Tobin & Masuda (2009 ▶). Acta Cryst. E65, o1217] is the hydrogen-bonded, dimeric orientation of the carb-oxy-lic acid functionalities.