Alkenes

Alkenes are unsaturated hydrocarbons that contain at least one carbon-carbon double bond. An alkene with exactly one C=C double bond has two hydrogen atoms fewer than the alkane with the same number of carbons, giving alkenes the general molecular formula CnH2n, for n = 2, 3, 4 and so on (the IUPAC naming of alkenes was already introduced in Chapter 14). Alkenes are also known by the older name olefins, a name that survives from the observation that the very first member, ethene (ethylene), reacts with chlorine to give an oily liquid product. Beyond simple alkenes with one C=C, the aliphatic unsaturated hydrocarbons carrying two or three carbon-carbon double bonds are called, respectively, alkadienes and alkatrienes -- for example m …