Hydrogen compounds are only required to contain carbon. However, most of them also contain hydrogen, and because it is the carbon-hydrogen bond which gives this class of compounds most of its particular chemical characteristics, carbon-hydrogen bonds are required in some definitions of the word "organic" in chemistry. Millions of hydrocarbons are known, and they are usually formed by complicated synthetic pathways that seldom involve elementary hydrogen. Compounds of hydrogen are often called hydrides, a term that is used fairly loosely. The term "hydride" suggests that the H atom has acquired a negative or anionic character, denoted H, and is used when
Carbon–hydrogen bond activation by a rhodium complex. In the case of alkanes, exclusive terminal functionalization was observed. Later, ruthenium catalysts were discovered to have higher activity and functional group compatibility. Other borylation catalysts have also been developed, including iridium-based catalysts, which successfully activate C-H bonds with high compatibility. For more information, consult borylation. No applications have been commercialized for homogeneously catalyzed C-H activations. Naturally occurring methane is not utilized as a chemical feedstock, despite its abundance and low cost. Current technology makes prodigious use of methane by steam reforming to produce syngas, a mixture of carbon monoxide and hydrogen. This syngas is then