This maximum is often explained by steric hindrance, but its origins sometimes actually lie in hyperconjugation ( as when the eclipsing interaction is of two hydrogen atoms ).
32.
The ? anomer is the major conformer, although somewhat controversially; this is due to the anomeric effect with the stabilisation energy provided by n-? * hyperconjugation.
33.
This type of bond also occurs in carbon compounds, where it is sometimes referred to as hyperconjugation; another name for asymmetrical three-center two-electron bonds.
34.
Goodman also conducted studies to determine the contribution of vicinal ( between two methyl groups ) vs . geminal ( between the atoms in a single methyl group ) interactions to hyperconjugation.
35.
I can accept that deprotonation ( of an alcohol ) is generally faster than SN2 . . . and maybe the chloro group makes the alcohol more acidic ( by inductance and hyperconjugation ).
36.
Hyperconjugation, which describes the stabilizing interaction between the HOMO of the alkyl group and the LUMO of the double bond, also helps explain the influence of alkyl substitutions on the stability of alkenes.
37.
In the hyperconjugation model, the donation of electron density from the C H ? bonding orbital to the C F ? * antibonding orbital is considered the source of stabilization in the gauche isomer.
38.
Negative hyperconjugation is most commonly observed when the ? *-orbital is located on certain C F or C O bonds, and does not occur to an appreciable extent with normal C H bonds.
39.
One common criticism of the hyperconjugation theory is that it fails to explain why the anomeric effect is not observed when substituted tetrahydropyran molecules are placed in polar solvents, and the equatorial position is once again preferred.
40.
An example is the Friedel Crafts alkylation of benzene with 1-chloro-2-methylpropane; the carbocation rearranges to a " tert "-butyl group stabilized by hyperconjugation, a particular form of delocalization.
