Hydrogen atom abstraction or hydrogen atom transfer (HAT) in chemistry is any chemical reaction in which a hydrogen free radical is abstracted from a substrate according to the general equation:
X. + H-Y -> X-H + Y.
Examples of HAT reactions are oxidative reactions in general, hydrocarbon combustion and reactions involving cytochrome P450 containing an iron(V)-oxo unit. The abstractor is usually a radical species itself. An example of a closed-shell abstractor is chromyl chloride. HAT can take place through proton-coupled electron transfer.
Non-radical Hydrogen Abstraction
It is reported in literature that during the synthesis of a Coelenterazine derivative, a non-radical hydrogen abstraction was observed on a substituted aminoimidazole in a typical Sandmayer hyroxilation condition.