Organic redox reaction
Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions because many reactions carry the name but do not actually involve electron transfer in the electrochemical sense of the word.
Simple functional groups can be arranged in order of increasing oxidation state. The oxidation numbers are only an approximation:
oxidation number -4 for alkanes,
oxidation number -2 for alkenes, alcohols, alkyl halides, amines,
oxidation number 0 for alkynes, ketones, aldehydes, geminal diols,
oxidation number +2 for carboxylic acids, amides, chloroform and
oxidation number +4 for carbon dioxide, tetrachloromethane.
When methane is oxidized to carbon dioxide its oxidation number changes from -4 to +4. Classical reductions include alkene reduction to alkanes and classical oxidations include oxidation of alcohols to aldehydes. In oxidations electrons are removed and the electron density of a molecule is reduced. In reductions electron density increases when electrons are added to the molecule. This terminology is always centered on the organic compound. For example, it is usual to refer to the reduction of a ketone by lithium aluminium hydride, but not to the oxidation of lithium aluminium hydride by a ketone. Many oxidations involve removal of hydrogen atoms from the organic molecule, and the reverse reduction adds hydrogens to an organic molecule.