Name : 2 - PENTYNE Molecular Formula : C5H8. Molecular Weight : 68.12. CAS : 627 - 21 - 4 Purity Grade : >98%. Boiling Point (bp) : 55 oC - 56 oC Density : 0.710. ELINCS/EINECS Number : 2109892 BRN : 1696938 Beilstein Index : 1, 250 Hazard Symbol : Highly flammable, Keep Cold Packaging Standard : UN 1993 CH3CH2C CCH3