26912-33-4 542-92-7 cyclopenta-1,3-diene CHEBI:30664 nchembio775-comp8 1,3-CYCLOPENTADIENE Cyclopentadiene EINECS 208-835-4 HSDB 2514 Pentole Pyropentylene R-Pentine ghl.PD_Mitscher_leg0.1205 InChI=1/C5H6/c1-2-4-5-3-1/h1-4H,5H