Doublebondforming

Doublebondforming refers to chemical processes that create a double bond, most often a carbon–carbon double bond (C=C), between two adjacent atoms. It is a key step in constructing alkenes and other unsaturated systems.

Common routes include dehydrogenation, dehydration, and elimination reactions. Dehydrogenation removes two hydrogen atoms from neighboring carbon atoms or from a saturated fragment; dehydration removes a water molecule from an alcohol to form an alkene; elimination reactions, such as E1 or E2, remove a leaving group and a hydrogen to generate a double bond.

Mechanistically, forming a pi bond involves reorganization of electrons and the formation of a pi bond through overlap of adjacent p orbitals after rehybridization from sp3 to sp2 in the carbon atoms involved. Conditions such as heat, acid catalysts, or transition-metal catalysts lower the energy barrier and enable the formation of the double bond under practical conditions.

Examples include industrial production of ethene by dehydrogenation of ethane; dehydration of ethanol to yield ethene; biological desaturation of fatty acids by desaturase enzymes; and various synthetic routes in organic synthesis that install alkenes at defined positions.

Considerations in doublebondforming include regioselectivity and stereochemistry (cis/trans arrangements), competing reactions that may reduce yield or alter structure, catalyst choice, and safety and environmental aspects associated with the reagents and products involved.