debrominate

Debrominate is the chemical process of removing bromine atoms from an organic substrate. It is used to convert brominated compounds into less brominated or fully debrominated products and can be viewed as the reverse of bromination.

Common methods include catalytic hydrogenolysis and other reductive approaches. In catalytic hydrogenolysis, a carbon–bromine bond is cleaved with hydrogen in the presence of a transition metal catalyst (for example palladium on carbon, nickel, or platinum), releasing bromide. Alternative chemical routes employ strong reducing agents such as zinc, iron, or borohydride in suitably chosen solvents, or photochemical and electrochemical strategies. Biological debromination is also observed, whereby specialized microbes or enzymes called dehalogenases remove bromine atoms from organobromines under aerobic or anaerobic conditions.

In environmental chemistry, debromination is a key step in the degradation and detoxification of brominated flame retardants such as PBDEs. Partial debromination yields lower-brominated congeners, and further reactions can lead to non-brominated backbones, with potential changes in toxicity and persistence. Debromination can occur abiotically in engineered remediation systems or biotically in contaminated sites.

Analytical monitoring of debromination products is usually done by gas or liquid chromatography coupled with mass spectrometry. Considerations in debromination include selectivity for brominated sites, formation of intermediate species, energy requirements, and the environmental implications of reaction byproducts. Related processes include dehalogenation more broadly, of which debromination is a subset.