Hydrogen atom abstraction

In chemistry, hydrogen atom abstraction, or hydrogen atom transfer (HAT), refers to a class of chemical reactions where a hydrogen free radical (a neutral hydrogen atom) is removed from a substrate with another molecule. This process follows the general equation:

${\displaystyle {\ce {X^{\bullet }{}+H-Y->X-H{}+Y^{\bullet }}}}$

HAT reactions are common in various redox reactions, hydrocarbon combustion, and interactions involving cytochrome P450 that contain an Fe(V)O unit. The entity removing the hydrogen atom, known as the abstractor (

X•), is often a radical itself, though in some instances, it may be a species with a closed electron shell, such as chromyl chloride. Hydrogen atom transfer can occur via a mechanism known as proton-coupled electron transfer. An illustrative synthetic instance of HAT is observed in iron zeolites, which facilitate the stabilization of alpha-oxygen.