9.0 Organic reactions

  General Organic Chemistry

The organic reaction involves the breaking and making of covalent bonds. The breaking and making of covalent bonds usually occurs in several discrete steps before transformation into product. The detailed sequential description of all steps of the transformation into products is called as the mechanism of a reaction.

Complete information regarding all the steps is seldom obtained. However, a good deal of data can be gathered from the following.

(a). study of the kinetics of the reaction
(b) isolation of intermediate, if isolable
(c) study of reaction in the presence of other similar substrate
(d) study of the isotopically labelled atom in the reactants
(e) trapping of free radicals
(f) crossover experiments
(g) stereochemical aspects etc.

Reaction mechanism can be visualised as,

\[{\text{Reactant}}\xrightarrow[{{\text{temperature/light/pressure}}}]{{{\text{solvent}}}}\begin{array}{c} {\left[ {{\text{Intermediate}}} \right]} \\ {{\text{or}}} \\ {\left[ {{\text{Transition state}}} \right]} \end{array} \to {\text{Product}}\]

Types of organic reaction

Organic reactions are classifieds mainly in four types,

(i) Substitution or displacement reactions
(ii) Addition reactions
(iii) Elimination reactions
(iv) Rearrangement reactions