Cyclopropane (75-19-4)

 Cyclopropane (CAS No.:75-19-4) is a cycloalkane molecule with the molecular formula C₃H₆, consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms. Cyclopropane and propene have the same empirical formula but have different structures, making them structural isomers.The bonds between the carbon atoms are considerably weaker than in a typical carbon-carbon bond, yielding reactivity similar to or greater than alkenes. Baeyer strain theory explains why: the angle strain from the 60° angle between the carbon atoms (less than the normal angle of 109.5° for bonds between atoms with sp3 hybridised orbitals) reduces the compound's carbon-carbon bond energy, making it more reactive than other cycloalkanes such as cyclohexane and cyclopentane. The molecule also has torsional strain due to the eclipsed conformation of its hydrogen atoms. It is somewhat stabilized by some pi character in its carbon-carbon bonds, indicated by the Walsh orbital description whereas it is modeled as a three-center-bonded orbital combination of methylene carbenes. Bent bonds also describe the bonding in cyclopropane.The smallest polycyclic compounds contain multiple fused cyclopropane rings. Tetrahedrane contains four fused cyclopropane rings which form the faces of a tetrahedron.Propellane contains three cyclopropane rings which share a single central carbon-carbon bond.It is an anaesthetic when inhaled. In modern anaesthetic practice, it has been superseded by other agents, due to its extreme reactivity under normal conditions: when the gas is mixed with oxygen there is a significant risk of explosion.

IARC Cancer Review: Animal No Adequate Data IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 , 1987,p. 93.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) . Reported in EPA TSCA Inventory.