Alkyl levulinates as `green chemistry' precursors: butane-1,4-diyl bis­(4-oxo­pentan­oate) and hexane-1,6-diyl bis­(4-oxo­pentan­oate)

Levulinic acid derivatives are potential `green chemistry' renewably sourced mol­ecules with utility in industrial coatings applications. Suitable single crystals of the centrosymmetric title compounds, C₁₄H₂₂O₆ and C₁₆H₂₆O₆, respectively, were obtained with difficulty. The data for the latter hexane-1,6-diyl compound were extracted from the major fragment of a three-component twinned crystal. Both compounds crystallize in similar-sized unit cells with identical symmetry, utilizing the same weak nonconventional attractive C-H...O(ketone) hydrogen bonds via C(4) and C(5) motifs, which expand to R²₂(30) ring and C²₂(14) chain motifs. Their different packing orientations in similar-sized unit cells suggest that crystal growth involving packing mixes could lead to inter­growths or twins.