1H-Cyclopenta(1,2-c:3,4-c')difuran-1,3,4,6(3aH)-tetrone, tetrahydro- 283171-26-6 6053-68-5 EINECS 227-964-7 r-1,c-2,c-3,c-4-Cyclopentane-1,2:3,4-tetracarboxylic dianhydride