Newman projection cyclohexane, boat conformation

The two main conformational shapes for cyclohexane are called the chair and the boat (Fig.M). The chair form is more stable than the boat form since the latter has eclipsed C-C and C-H bonds. This can be observed in the Newman projections (Fig.N) that have been drawn in such a way that we are looking along two bonds at the same time-bonds 2-3 and 6-5. In the chair conformation, there are no eclipsed C-C bonds. But, in the boat conformation, bond 1-2 is eclipse with bond 3-4, and bond 1-6 is eclipsed with bond 5-4. This indicates that the boat conformation is less stable than the chair conformation and the majority of... 

Fig.N. Newman projections of the chair and boat conformations of cyclohexane.

The boat conformation of cyclohexane (18) can be constructed from a molecular model of the chair form by holding the right-hand three carbons C(2), C(3) and C(4) of 15, clamped from the top with the hand and moving the left-hand three carbons upward. A Newman projection of the boat form looking along the C(l)-C(2) bond, and shown in 19, is reminiscent of the highest energy cis conformation of butane. 

The boat conformer of cyclohexane, a Newman projection of the boat conformer, and a ball-and-stick model showing that some of the bonds are eclipsed. 

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