Polymorphism and symmetry non-equivalence in (3-carboxymethoxy-naphthalen-2-yloxy) acetic acid

The crystal structures of two polymorphs of (3-carboxymethoxynaphthalen-2-yloxy) acetic acid are determined. Symmetry non-equivalence in the lattice of one of the polymorph of the acid that has P21/c space group is observed. The structures of these polymorphs are compared with the two polymorphs of the methylester of (3-carboxymethoxynaphthalen-2-yloxy) acetic acid. The two polymorphs of the (3-carboxymethoxynaphthalen-2-yloxy) acetic acid have significant differences in the layered packing patterns formed by weak interactions. Different packing arrangements of the polymorphic esters arise from different conformers.