4,4'-ethyne-1,2-diyldibenzoic acid InChI=1/C16H10O4/c17-15(18)13-7-3-11(4-8-13)1-2-12-5-9-14(10-6-12)16(19)20/h3-10H,(H,17,18)(H,19,20 benzoic acid, 4,4'-(1,2-ethynediyl)bis-