Search results
Results from the WOW.Com Content Network
Hyperconjugation can be used to rationalize a variety of chemical phenomena, including the anomeric effect, the gauche effect, the rotational barrier of ethane, the beta-silicon effect, the vibrational frequency of exocyclic carbonyl groups, and the relative stability of substituted carbocations and substituted carbon centred radicals, and the thermodynamic Zaitsev's rule for alkene stability.
The Cieplak effect relies on the stabilizing interaction of mixing full and empty orbitals to delocalize electrons, known as hyperconjugation. [2] When the highest occupied molecular orbital of one system and the lowest unoccupied molecular orbital of another system have comparable energies and spatial overlap, the electrons can delocalize and sink into a lower energy level.
This phenomenon, a type of resonance, can stabilize the molecule or transition state. [2] It also causes an elongation of the σ-bond by adding electron density to its antibonding orbital. [1] Negative hyperconjugation is seldom observed, though it can be most commonly observed when the σ *-orbital is located on certain C–F or C–O bonds ...
Negative hyperconjugation is a theorized phenomenon in organosilicon compounds, in which hyperconjugation stabilizes or destabilizes certain accumulations of positive charge. The phenomenon explains corresponding peculiarities in the stereochemistry and rate of hydrolysis .
The gauche effect is very sensitive to solvent effects, due to the large difference in polarity between the two conformers.For example, 2,3-dinitro-2,3-dimethylbutane, which in the solid state exists only in the gauche conformation, prefers the gauche conformer in benzene solution by a ratio of 79:21, but in carbon tetrachloride, it prefers the anti conformer by a ratio of 58:42. [9]
In 1935 Baker and Nathan explained the observed difference in terms of a conjugation effect and in later years after the advent of hyperconjugation (1939) as its predecessor. A fundamental problem with the effect is that differences in the observed order are relatively small and therefore difficult to measure accurately.
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.
Casimir effect (quantum field theory) (physical phenomena) Castle thunder (sound effect) (in-jokes) (sound effects) Catapult effect (electromagnetism) Catch-up effect (economics effects) Catfish effect (human resource management) (management) (organizational studies and human resource management) (social psychology) Cause and effect