Carbon Hydrogen Bond

A carbon-hydrogen bond ( C-H bond ) is a bond between carbon and hydrogen atoms that can be found in many organic compounds . [1] This bond is a covalent bond which means that carbon shares its outer valence electrons with four hydrogens. It makes them stable by completing both their outer shells. [2] The carbon-hydrogen bond has a bond length of about 1.09 (1.09 × 10 -10 m) and a bond energy of about 413 kJ / mol (see table below). Pauling’s scaleto use—C (2.55) and H (2.2)—the difference in electronegativity between these two atoms is 0.35. Because of this small difference in electronegativity, the C–H bond is generally considered to be nonpolar. In structural formulas of molecules, hydrogen atoms are often omitted. The compound classes containing only C–H bonds and C–C bonds are alkanes , alkanes , alkynes , and aromatic hydrocarbons . Collectively they are known as hydrocarbons .

In October 2016, astronomers reported that the very basic chemical element of life —the carbon-hydrogen molecule (CH, or methylidyne radical ), carbon-hydrogen positive ion (CH+) and carbon ion (C+)—results in, The bulk of ultraviolet light from stars is the result of turbulent events involving supernovae and young stars , rather than the other way around , as previously thought.

Bond length

The length of the carbon–hydrogen bond varies slightly with the hybridization of the carbon atom. A bond between a hydrogen atom and a sp2 hybridised carbon atom is approximately 0.6% less than that between hydrogen and sp3 hybridised carbon. A bond between the hydrogen and the sp hybridized carbon is still short, about 3 % smaller than sp3CH. This trend is illustrated by the molecular geometry of ethane, ethylene and acetylene.


The C–H bond is normally very strong, so it is relatively inactive. In many compound classes, collectively called carbonic acids , the C –H bond can be sufficiently acidic for proton removal. Inactive C–H bonds are found in alkanes and are not adjacent to a heteroatom (O, N, C, etc.). Such bonds usually only participate in radical substitution . However, several enzymes are known to affect these reactions. [5]

Although the C–H bond is one of the strongest, it varies in magnitude by more than 30% for fairly stable organic compounds, even in the absence of the heteroatom .

bondhydrocarbon radicalMolar Bond Dissociation Energy (Kcal)Molar Bond Dissociation Energy (kJ)
CH 3 -Hmethyl104440
2 H 5 -Hethyl98410
(CH 3 ) 2 HC−Hisopropyl95400
(CH 3 ) 3 C−Htert-butyl93390
CH2 = CH − Hvinyl112470
6 H 5 -H−phenyl110460
CH 2 =CHCH 2 -Hallele88370
6 H 5 CH 2 -H−frankincense85360
oc 4 h 7 -htetrahydrofuranil92380
CH 3 C (O) CH 2 -Hacetonyl96400