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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.
It is also utilized in the field of medicine, for example to allow for the administration of medicine across the blood–brain barrier via lipid nanoparticles. [2] The Trojan Horse effect is utilized by some antibiotics. By having the active compound bound to a mimic compound of molecules which are desirable to the bacteria. [3]
Hyperconjugation model for explaining the gauche effect in 1,2-difluoroethane. Key in the bent bond explanation of the gauche effect in difluoroethane is the increased p orbital character of both C−F bonds due to the large electronegativity of fluorine. As a result, electron density builds up above and below to the left and right of the ...
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 ...
Free-radical intermediate is stabilized by hyperconjugation; adjacent occupied sigma C–H orbitals donate into the electron-deficient radical orbital. A new method of anti-Markovnikov addition has been described by Hamilton and Nicewicz, who utilize aromatic molecules and light energy from a low-energy diode to turn the alkene into a cation ...
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.
The hook effect refers to the prozone phenomenon, also known as antibody excess, or the postzone phenomenon, also known as antigen excess. It is an immunologic phenomenon whereby the effectiveness of antibodies to form immune complexes can be impaired when concentrations of an antibody or an antigen are very high.