Organic Chemistry/Introduction to reactions/Overview of addition, elimination, substitution and rearrangement reactions

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The real heart of organic chemistry is the reactions. Everything that you study is geared to prepare you for organic syntheses and other chemical transformations performed in the lab. This chapter gives you the basic tools to begin looking at these reactions.

Some basic reaction types[edit]

One way to organize organic reactions places them into a few basic categories:

  • addition reactions
  • elimination reactions
  • substitution reactions
  • rearrangement reactions

Other categories include:

  • Oxidations
  • Reductions
  • Alkylations

Sometimes one reaction can fall into more than one category. These classifications are just a tool and are not rigid.

Addition reaction[edit]

Something is added to something else to produce a third thing.

A + B → C

Note: the letters A, B and C here represent any atomic, ionic or molecular species which can undergo this type of reaction.

Elimination reaction[edit]

Something comes off of a molecule, resulting in two products.

A → B + C

Substitution reactions[edit]

This involves the exchange of one group for another.

AB + CD → AC + BD

Common reaction types include

  • radical reactions and
  • nucleophilic substitutions
    • SN1, Unimolecular nucleophilic substitution
    • SN2, Bimolecular nucleophilic substitution

Rearrangement reactions[edit]

A molecule shifts or otherwise rearranges to form a different molecule.

A → B

This typically happens when one molecule changes into an isomer of itself.

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