Steric effects

A-values provide another measure of the bulk of substituents. A-values are derived from equilibrium measurements of monosubstituted cyclohexanes.^[4][5][6][7] The extent that a substituent favors the equatorial position gives a measure of its bulk.

Ceiling temperature (${\displaystyle T_{c}}$) is a measure of the steric properties of the monomers that comprise a polymer. ${\displaystyle T_{c}}$ is the temperature where the rate of polymerization and depolymerization are equal. Sterically hindered monomers give polymers with low ${\displaystyle T_{c}}$'s, which are usually not useful.

Cone angles

Steric effects are critical to chemistry, biochemistry, and pharmacology. In organic chemistry, steric effects are nearly universal and affect the rates and activation energies of most chemical reactions to varying degrees.

In biochemistry, steric effects are often exploited in naturally occurring molecules such as enzymes, where the catalytic site may be buried within a large protein structure. In pharmacology, steric effects determine how and at what rate a drug will interact with its target bio-molecules.

• Prominent sterically hindered compounds
• 
  Tris(2,4-di-tert-butylphenyl)phosphite, a widely used stabilizer in polymers.
• 
  phosphine ligand used in homogeneous catalysis and, with B(C₆F₅)₃, comprises the classic frustrated Lewis pair.^[10]
• 
  UV stabilizers and antioxidants for hydrocarbon-based products ranging from petrochemicals to plastics.^[11]
• 
  Hindered amine light stabilizers are widely used in polymers.^[12][13]
• 
  Titanium isopropoxide is a monomer, the corresponding titanium ethoxide is a tetramer.
• 
  An isolable selenenic acid owing to steric protection.^[14]

• Collision theory
• Reaction rate accelerate as result of steric hindrance in the Thorpe–Ingold effect
• Sterically induced reduction
• Intramolecular force
• Van der Waals strain, also known as steric strain

References