3,5-Bis[(pyridin-4-yl)meth­oxy]benzoic acid

Single crystals of the title compound, C(19)H(16)N(2)O(4), were obtained under hydro­thermal conditions by an unintended recrystallization of the employed microcrystalline starting material. The [(pyridin-4-yl)meth­oxy]benzoic acid unit is nearly planar, with a maximum deviation from the least-squares plane of 0.194 (2) Å. This plane is inclined by 35.82 (6)° to that defined by the second (pyridin-4-yl)meth­oxy group [in which the largest deviation from the least-squares plane is 0.013 (2) Å]. In the crystal, mol­ecules are linked by O—H⋯N hydrogen bonds involving the acid hy­droxy group and a pyridine N atom into chains parallel to [-201].