Alkene

"An alkene, sometimes called an olefin, is a hydrocarbon that contains a carbon– carbon double bond. Alkenes occur abundantly in nature. … Ethylene and propylene, the simplest alkenes, are the two most important organic chemicals produced industrially. Approximately 127 million metric tons of ethylene and 54 million metric tons of propylene are produced worldwide each year for use in the synthesis of polyethylene, polypropylene, ethylene glycol, acetic acid, acetaldehyde, and a host of other substances."

"Because of its double bond, an alkene has fewer hydrogens than an alkane with the same number of carbons … and is therefore referred to as unsaturated. Knowing this relationship, it’s possible to work backward from a molecular formula to calculate a molecule’s degree of unsaturation — the number of rings and/or multiple bonds present in the molecule. … The unknown therefore contains two double bonds, one ring and one double bond, two rings, or one triple bond. There’s still a long way to go to establish structure, but the simple calculation has told us a lot about the molecule. … Add the number of halogens to the number of hydrogens. … Ignore the number of oxygens. … Subtract the number of nitrogens from the number of hydrogens."

"The double bond in alkenes, such as ethene (ethylene), and the triple bond in alkynes, such as ethyne (acetylene), are the result of the ability of the atomic orbitals of carbon to adopt sp2 and sp hybridization, respectively."

"The carbon–carbon double bond in alkenes has special electronic and structural features. This section reviews the hybridization of the carbon atoms in this functional group, the nature of its two bonds (s and p), and their relative strengths."

"Alkenes possessing allylic C-H bonds are oxidized by SeO2 either to allylic alcohols or esters or to α,β-unsaturated aldehydes or ketones, depending on the experimental conditions. … Reaction of chromic anhydride (CrO2) with t-butanol yields t-butyl hydrogen chro- mate, a powerful oxidant suitable for allylic oxidation of electron-deficient alkenene. Copper(I) salts catalyze thc allylic oxidation of alkenes in the presence of peresters, such as tert-BuO2COPh, to afford the corresponding allylic benzoate esters."