Reaction classification oxidative addition mechanisms

The mechanisms of the usual organic reactions are now clearly established, and the reactions are classified as ionic, radical, and molecular. More detailed classifications have also been made. The mechanisms of many reactions involving non-transition metal compounds are clear enough for example, in the Grig-nard or Reformatsky reaction, the first step is the irreversible oxidative addition of alkyl halides to form Mg-carbon or Zn-carbon bonds, in which the carbon is considered to be a nucleophilic center or carbanion which reacts with various electrophiles. 

In addition to the classification of inhibitors according to their mechanisms of the action on oxidation, they can be classified into consumable and long-lived inhibitors. A consumable inhibitor is irreversibly consumed in its reactions with free radicals (R or RCV) or hydroperoxide. The stoichiometric coefficient of inhibition of such inhibitors is typically equal to one or two per inhibitory functional group. However, in some systems (for example RH 02 InH), an inhibitor can act cyclically so that, getting repeatedly regenerated, the... 

Examples of photoreactions may be found among nearly all classes of organic compounds. From a synthetic point of view a classification by chromo-phore into the photochemistry of carbonyl compounds, enones, alkenes, aromatic compounds, etc., or by reaction type into photochemical oxidations and reductions, eliminations, additions, substitutions, etc., might be useful. However, photoreactions of quite different compounds can be based on a common reaction mechanism, and often the same theoretical model can be used to describe different reactions. Thus, theoretical arguments may imply a rather different classification, based, for instance, on the type of excited-state minimum responsible for the reaction, on the number and arrangement of centers in the reaction complex, or on the number of active orbitals per center. (Cf. Michl and BonaCid-Kouteck, 1990.)... 

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