The electronic effects affecting the density distribution of intramolecular electron clouds are as follows

What are the electronic effects that affect the density distribution of intramolecular electron clouds?

field effect. Substituents can generate an electric field in space, which affects the reaction center at the other end. The electrostatic effect of this space is called field effect.

*** yoke effect. The system in which single and double bonds appear alternately is called * * * yoke system. In the * * * yoke system, an electronic effect that changes the distribution of π electrons (or P electrons) in the system due to the interaction between atoms is called * * * yoke effect.

induced effect. The effect that the bonding electron cloud moves in a certain direction along the atomic chain due to the different polarity (electronegativity) of atoms or groups in the molecule is called induced effect. The induced electron cloud is transmitted along the atomic chain. Its function decreases rapidly with the increase of distance, and generally only the influence of three bonds is considered.

super * * * yoke effect. When the C-H σ bond and π bond (or p orbital) are in the * * * yoke position, the delocalization phenomenon of electrons will also occur. This delocalization phenomenon of C-H σ-electrons is called super * * yoke effect.