Rearrangement reaction

Lore & Background

In organic chemistry, a rearrangement reaction is defined as a broad class of reactions that involves a change of connectivity. Usually the term refers to intramolecular processes involving modification of the carbon skeleton. Often a substituent moves from one atom to another atom in the same molecule, making these reactions typically intramolecular. For example, a substituent R can move from carbon atom 1 to carbon atom 2.

Reader's Guide

Rearrangement reactions are significant because they allow for the modification of molecular structure without adding or removing atoms, enabling the conversion of straight-chain alkanes into branched isomers, which have favorable combustion characteristics for internal combustion engines. The mechanism of alkyl group movement, as in the Wagner–Meerwein rearrangement, likely involves fluid transfer along a bond rather than discrete ionic bond-breaking and forming. In pericyclic reactions, orbital interactions provide a better explanation than simple discrete electron transfers. Although curved arrows can be drawn for a sequence of discrete electron transfers that give the same result, these are not necessarily realistic. The legacy of rearrangement reactions includes their application in large-scale industrial processes like skeletal isomerization in oil refineries, as well as in the production of certain nylons via the Beckmann rearrangement.

Did You Know?

• A 1,2-rearrangement involves a substituent moving from one atom to an adjacent atom.
• Skeletal isomerization is not normally encountered in the laboratory but is the basis of large applications in oil refineries.
• The Wagner–Meerwein rearrangement is an example of a 1,2-rearrangement.
• The Beckmann rearrangement is relevant to the production of certain nylons.