dehydrogenative

Dehydrogenative is an adjective used in chemistry to describe reactions that involve the removal of hydrogen from one or more substrates as part of forming a chemical bond, frequently with the concomitant evolution of molecular hydrogen. The term is often used in the context of dehydrogenative coupling or dehydrogenative bond formation, where two substrates are joined together with loss of H2, creating new C–C, C–N, C–O, or other bonds. This contrasts with dehydrogenation, which usually refers to removing hydrogen from a single molecule to generate a more unsaturated product or carbonyl compound; dehydrogenative reactions emphasize bond formation between two partners rather than simple oxidation of one substrate.

In practice, dehydrogenative processes encompass cross-dehydrogenative couplings (CDCs) in which two C–H bonds are activated and coupled, as well as cyclizations and other bond-forming steps that release hydrogen. They are frequently mediated by transition-metal catalysts (such as palladium, ruthenium, nickel, copper, or iron) or by heterogeneous catalysts, and may use external oxidants or proceed under redox-neutral conditions with H2 evolution as the only stoichiometric byproduct.

Typical examples include the dehydrogenative coupling of aryl C–H bonds to form biaryl compounds, and dehydrogenative cyclizations that convert diols or amino alcohols into cyclic ethers or heterocycles. Dehydrogenative strategies enable direct bond construction from readily available substrates and are studied in organic synthesis, catalysis, and materials science.

See also: dehydrogenation, oxidative coupling, C–H activation, cross-dehydrogenative coupling.