Comparison of the crystal structures of methyl 4-bromo-2-(meth­­oxy­meth­­oxy)benzoate and 4-bromo-3-(meth­­oxy­meth­­oxy)benzoic acid

The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo–hy­droxy–benzoic acids. Compound (II) crystallizes with two independent mol­ecules (A and B) in the asymmetric unit. In both (I) and (II), the O—CH2—O—CH3 side chain is not in its fully extended conformation; the O—C—O—C torsion angle is 67.3 (3) ° in (I), and −65.8 (3) and −74.1 (3)° in mol­ecules A and B, respectively, in compound (II). In the crystal of (I), mol­ecules are linked by C—H⋯O hydrogen bonds, forming C(5) chains along [010]. The chains are linked by short Br⋯O contacts [3.047 (2) Å], forming sheets parallel to the bc plane. The sheets are linked via C—H⋯π inter­actions, forming a three-dimensional architecture. In the crystal of (II), mol­ecules A and B are linked to form R22(8) dimers via two strong O—H⋯O hydrogen bonds. These dimers are linked into ⋯A–B⋯A–B⋯A–B⋯ [C22(15)] chains along [011] by C—H⋯O hydrogen bonds. The chains are linked by slipped parallel π–π inter­actions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) Å], leading to the formation of slabs parallel to the bc plane