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Cis-1,4-Di-tert-butylcyclohexane has an axial tert-butyl group in the chair conformation and conversion to the twist-boat conformation places both groups in more favorable equatorial positions. As a result, the twist-boat conformation is more stable by 0.47 kJ/mol (0.11 kcal/mol) at 125 K (−148 °C) as measured by NMR spectroscopy. [10]
It is known that axial bonds are more hindered than the corresponding equatorial bonds. This is because substituents in the axial position are relatively close to two other axial substituents. This makes it very crowded when bulky substituents are oriented in the axial position. These types of steric interactions are commonly known as 1,3 ...
Another accepted explanation for the anomeric effect is the equatorial configuration has the dipoles involving both heteroatoms partially aligned, and therefore repelling each other. [12] By contrast the axial configuration has these dipoles roughly opposing, thus representing a more stable and lower energy state.
The conformation which places the methyl group in the equatorial position is 3.16 kcal/mol more stable than the axial conformation. [7] The product ratio of 95:5 indicates that the more stable conformer leads to the major product.
The staggered conformation is more stable by 12.5 kJ/mol than the eclipsed conformation, which is the energy maximum for ethane. In the eclipsed conformation the torsional angle is minimised. staggered conformation left, eclipsed conformation right in Newman projection
The chair conformation of six-membered rings have a dihedral angle of 60° between adjacent substituents thus usually making it the most stable conformer. Since there are two possible chair conformation steric and stereoelectronic effects such as the anomeric effect, 1,3-diaxial interactions, dipoles and intramolecular hydrogen bonding must be taken into consideration when looking at relative ...
The apicophilicity of a substituent mainly depends on its electronegativity, but some other factors can also have an effect. A bulky substituent prefers equatorial positions, which are more distant from other substituents. A substituent with π-bonding ability also prefers equatorial positions. The use of multidentate ligands can also control ...
Another conformation of cyclohexane exists, known as boat conformation, but it interconverts to the slightly more stable chair formation. If cyclohexane is mono-substituted with a large substituent, then the substituent will most likely be found attached in an equatorial position, as this is the slightly more stable conformation.