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Introduction to Oxidation and Reduction

Oxidation

Most of the common oxidizing agents used in organic chemistry are inorganic compounds, such as:

Tab.1
Frequently used oxidizing agents in organic chemistry
MnO4 permanganate
MnO2 manganese dioxide
Cr2O72 dichromate
CrO3 chromium oxide
OsO4 osmium tetroxide
H2O2 hydrogen peroxide
R-O-O-R peroxide
Cl2 chlorine
ClO hypochlorite
O2 / cat. air + transition metal oxides as catalysts
O2 / hν irradiation with photosensitizers in air (photooxidation)
e electrochemical processes (anionic oxidation)

The oxidation of functional groups, such as C=C double bonds, alcohols, aldehydes, ketones, benzylic and allylic H atoms or functional groups containing N, S or P, is carried out in most cases with specifically tailored reagents that meet certain conditions. On the other hand, the selective oxidation of C-H bonds in alkanes and aromatic compounds has not been solved satisfactorily. Though tertiary H atoms are more reactive than secondary and primary ones, the oxidation of hydrocarbons usually leads to a mixture of products and structural fragmentation (in extreme cases combustion can lead to CO2 and water).

Organic oxidation reactions are normally divided into three categories:

  1. Dehydrogenation (removal of H2 )
  2. Oxidation by replacement of hydrogen with oxygen
  3. Oxidation by addition of oxygen
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