<unk>  reductions or<unk>  oxidations or<unk> s are<unk><unk> s that take place with<unk>  compounds. In<unk>  chemistry oxidations and reductions are different from ordinary<unk><unk> s because many<unk> s carry the name but do not actually involve electron transfer in the electrochemical sense of the word.
Following the rules for determining the oxidation number for an individual carbon atom leads to
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.
Methane is oxidized to carbon dioxide because the oxidation number changes from -4 to +4. Classical reductions include alkene reduction to alkanes and classical oxidations include oxidation of alcohols to aldehydes with manganese dioxide. 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 around the<unk>  compound. So a ketone is always reduced by Lithium aluminium hydride but it is bad form to have lithium aliminium hydride oxidized by a ketone. Many oxidations involve removal of protons from the<unk>  molecule and the reverse reduction adds protons to an<unk>  molecule.
Many<unk> s classified as reductions also appear in other classes. For instance conversion of the ketone to an alcohol by Lithium aluminium hydride can be considered a reduction but the hydride is also a good nucleophile in nucleophilic substitution. Many<unk><unk> s in<unk>  chemistry have coupling<unk> <unk>  mechanism involving free radical intermediates. True<unk><unk>  chemistry can be found in electrochemical<unk>  synthesis or electrosynthesis. Examples of<unk><unk> s that can take place in an electrochemical cell are the Kolbe electrolysis 
In disproportionation<unk> s the reactant is both oxidised and reduced in the same chemical<unk>  forming 2 separate compounds.
Asymmetric catalytic reductions and asymmetric catalytic oxidations are important in asymmetric synthesis.
Organic redox reaction
Free radical reaction
Exothermic reaction
Organic reaction
Hydrogen-deuterium exchange
Dielectric relaxation
Condensation reaction
Host-guest chemistry