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The chair conformation cannot deform without changing the bond angles or lengths. We can think of it as two chains, mirror images one of the other, containing atoms (1,2,3,4) and (1,6,5,4), with opposite dihedral angles. The distance from atom 1 to atom 4 depends on the absolute value of the dihedral angle.
The chair conformation minimizes both angle strain and torsional strain by having all carbon-carbon bonds at 110.9° and all hydrogens staggered from one another. [2] The conformational changes that occur in a cyclohexane ring flip take place over several stages. Structure D (10.8 kcal/mol) is the highest energy transition state of the process.
The chair conformation is the favored configuration, because in this conformation, the steric strain, eclipsing strain, and angle strain that are otherwise possible are minimized. [4] Which of the possible chair conformations predominate in cyclohexanes bearing one or more substituents depends on the substituents, and where they are located on ...
For example, the tert-butyl group (A-value=4.9) has a larger A-value than the trimethylsilyl group (A-value=2.5), yet the tert-butyl group actually occupies less space. This difference can be attributed to the longer length of the carbon–silicon bond as compared to the carbon–carbon bond of the tert -butyl group.
Most methylcyclohexane is extracted from petroleum but it can be also produced by catalytic hydrogenation of toluene: CH 3 C 6 H 5 + 3 H 2 → CH 3 C 6 H 11. The hydrocarbon is a minor component of automobile fuel, with its share in US gasoline varying between 0.3 and 1.7% in early 1990s [10] and 0.1 to 1% in 2011. [11]
A Newman projection is a drawing that helps visualize the 3-dimensional structure of a molecule. [1] This projection most commonly sights down a carbon-carbon bond, making it a very useful way to visualize the stereochemistry of alkanes.
For octahedral complexes of formula MX 4 Y 2, two isomers also exist. (Here M is a metal atom, and X and Y are two different types of ligands.) In the cis isomer, the two Y ligands are adjacent to each other at 90°, as is true for the two chlorine atoms shown in green in cis-[Co(NH 3) 4 Cl 2] +, at left.
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