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Steric hindrance is a consequence of steric effects. Steric hindrance is the slowing of chemical reactions due to steric bulk. It is usually manifested in intermolecular reactions, whereas discussion of steric effects often focus on intramolecular interactions. Steric hindrance is often exploited to control selectivity, such as slowing unwanted ...
The protonation of substituted aniline is inhibited by steric hindrance. When protonated, the nitrogen in the amino group changes its orbital hybridization from sp 2 to sp 3 , becoming non-planar. This leads to steric hindrance between the ortho-substituted group and the hydrogen atom of the amino group, reducing the stability of the conjugate ...
Steric hindrance is significant in polymers derived from α-methylstyrene because the phenyl and methyl groups are bonded to the same carbon. These steric effects in combination with stability of the tertiary benzylic α-methylstyryl radical give α-methylstyrene its relatively low ceiling temperature.
Van der Waals strain, or steric strain, occurs when atoms are forced to get closer than their Van der Waals radii allow. [ 4 ] : 5 Specifically, Van der Waals strain is considered a form of strain where the interacting atoms are at least four bonds away from each other. [ 5 ]
Van der Waals strain is also called Van der Waals repulsion and is related to steric hindrance. [1] One of the most common forms of this strain is eclipsing hydrogen , in alkanes . In rotational and pseudorotational mechanisms
The stereoelectronic effect, which is the interaction shown above when the acceptor orbital is the σ*(Si–CH 3), appears to be a more predominant factor in determining the reaction selectivity against the steric hindrance and even wins over the penalty of the disrupted conjugation system of the product due to steric clash. [23]
A very steep slope will correspond to high steric sensitivity, while a shallow slope will correspond to little to no sensitivity. Since E s values are large and negative for bulkier substituents, it follows that: If δ is positive, increasing steric bulk decreases the reaction rate and steric effects are greater in the transition state.
Tertiary alkoxides tend to give elimination reaction because of steric hindrance. The alkylating agent, on the other hand is most preferably primary. Secondary alkylating agents also react, but tertiary ones are usually too prone to side reactions to be of practical use.