Carbon–hydrogen bond activation Carbon–hydrogen bond activation Carbon–hydrogen bond functionalization (C–H functionalization) is a type of reaction in which a carbon–hydrogen bond is cleaved and replaced with a carbon-X bond (where X is usually carbon, oxygen, or nitrogen). The term usually implies that a transition metal is involved in the C-H cleavage process. Reactions classified by the term typically involve the hydrocarbon first to react with a metal catalyst to create an organometallic complex in which the hydrocarbon is coordinated to the inner-sphere of a metal, either via an intermediate "alkane or arene complex" or as a transition state leading to a "M−C" intermediate.
Hydrogen isotope biogeochemistry often sold with the guarantee that chemical additives come from natural sources. This claim becomes difficult to evaluate when the chemical compound has a known structure and is readily synthesized in the lab. Authentication of claims regarding the origins of these chemicals has made good use of various stable isotopes, including those of hydrogen. Combined carbon and hydrogen isotope analysis has been used to test the authenticity of (E)-methyl cinnamate, γ-decalactone and δ-decalactone. Hydrogen and nitrogen isotope ratios have been used for the authentication of alkylpyrazines used as "natural" coffee flavorings. The isotope ratio of carbon in the steroids of