Organic reaction

The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions.

Polar reactions are characterized by the movement of electron pairs from a well-defined source (a nucleophilic bond or lone pair) to a well-defined sink (an electrophilic center with a low-lying antibonding orbital).

Participating atoms undergo changes in charge, both in the formal sense as well as in terms of the actual electron density.

Finally, pericyclic reactions involve the redistribution of chemical bonds along a cyclic transition state.

Although electron pairs are formally involved, they move around in a cycle without a true source or sink.

Of course, some chemical processes may involve steps from two (or even all three) of these categories, so this classification scheme is not necessarily straightforward or clear in all cases.

Factors specific to organic reactions are those that determine the stability of reactants and products such as conjugation, hyperconjugation and aromaticity and the presence and stability of reactive intermediates such as free radicals, carbocations and carbanions.

Selectivity in terms of regioselectivity, diastereoselectivity and enantioselectivity is therefore an important criterion for many organic reactions.

For example, in the Fries rearrangement the reactant is an ester and the reaction product an alcohol.

Organic reactions can also be classified by the type of bond to carbon with respect to the element involved.