Reaction types in organic chemistry

Reactions in organic chemistry are divided into different types. The three most important types are:

• Additions In addition reactions something is added to the substrate. Addition reactions can be classified as either electrophilic or nucleophilic, depending on the nature of the species adding to the substrate: If it is a nucleophile, adding to an electrophilic substrate, then the reaction is a nucleophilic addition reaction. If, on the other hand, an electrophile is added to the substrate, which is nucleophilic, then the reaction is an electrophilic addition reaction.

• Eliminations An elimination reaction is the opposite of an addition reaction. Something is eliminated (broken off) from the substrate. This could be an alcohol eliminating a water molecule to create a double bond, in which case the reaction would be a dehydration. Elimination reactions are classified as either E1, E2 or E1cB, depending on the reaction mechanism.

• Substitutions In a substitution reaction one part of a molecule is substituted for something else. If the new substituent is a nucleophile, then the reaction is a nucleophilic substitution, whereas if the new substituent is an electrophile, then the reaction is an electrophilic substitution. For the nucleophilic substitutions there is a distinction between S_N1 or S_N2 reactions, which are substitutions on an sp³ hybridized atom, and substitutions on sp² hybridized atoms.

Of other reaction types can be mentioned: Rearrangements, oxidation, reduction, combustion and radical reactions.