Skew boat

The various conformations of cyclohexane are m rapid equilibrium with one another but at any moment almost all of the molecules exist m the chair conformation Not more than one or two molecules per thousand are present m the skew boat confer matron Thus the discussion of cyclohexane conformational analysis that follows focuses exclusively on the chair conformation... 

A potential energy diagram for nng inversion m cyclohexane is shown m Figure 3 18 In the first step the chair conformation is converted to a skew boat which then proceeds to the inverted chair m the second step The skew boat conformation is an inter mediate in the process of ring inversion Unlike a transition state an intermediate is not a potential energy maximum but is a local minimum on the potential energy profile... 

Section 3 7 Three conformations of cyclohexane have approximately tetrahedral angles at carbon the chair the boat and the skew boat The chair is by far the most stable it is free of torsional strain but the boat and skew boat are not When a cyclohexane ring is present m a compound it almost always adopts a chair conformation... 

Skew boat (Section 3 7) An unstable conformation of cyclo hexane It is slightly more stable than the boat conforma tion... 

Twist boat (Section 3 7) Synonymous with skew boat... 

A modified boat conformation of cyclohexane, known as the twist boat (Fig. 1.8), or skew boat, has been suggested to minimize torsional and nonbounded interactions. This particular conformation is estimated to be about 1.5 kcal moE (6 kJ moE ) lower in energy than the boat form at room temperature. 

NPC12)(NSOPh)2 PN 157.3 Skew boat els-phenyl groups 192... 

The true boat actually lies at the energy maximum between two skew-boats and has been found to be 1.6 kcal/mole less stable than the latter. 

An interesting experimental result concerns the most stable conformation of 1,4-cyclohexadione. This molecule is found to exist preferentially in a skew boat conformation228, 229 This conformation may be a result of a compromise between nonbonded attraction, which is maximized in the boat conformation, and steric effects which favor the chair conformation. Obviously, this molecule does not... 

Twist (skew) boat boat-chair chair almost planar... 

Figure 9a. Spherical polar depiction of pyranose puckering. The equatorial belt is the path of facile pseudorotation through all the Boats and Skew-boats rotation). Perfect chairs are at the North and South poles, and the Half-boat (Envelope) forms are at 6 of 54.7. This diagram has a reversed direction of positive pseudorotation from that shown in figure 3, Chapter 1.

Previously, our molecular mechanics studies showed that the iduronate ring can adopt the (skew boat)... 

The conformation of two 4-phenylsulfonyl-tetrahydropyran-2-one derivatives both in solution and in the solid state was studied (95JP0747) the tetrahydropyran-2-one ring proved to adopt a skew-boat conformation. 

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