how to draw boat conformation on chem draw

If two carbon atoms on opposite sides of the six-membered ring are lifted out of the plane of the ring, much of the angle strain can be eliminated. The resulting angle and eclipsing strains would severely destabilize this structure. Also, every carbon-carbon bond in such a structure would be eclipsed. The bond angles would necessarily be 120º, 10.5º larger than the ideal tetrahedral angle. Some Conformations of Cyclohexane RingsĪ planar structure for cyclohexane is clearly improbable.

Cycloheptane and cyclooctane have greater strain than cyclohexane, in large part due to transannular crowding (steric hindrance by groups on opposite sides of the ring). Cyclohexane is a good example of a carbocyclic system that virtually eliminates eclipsing and angle strain by adopting non-planar conformations, such as those shown below. However, this strain, together with the eclipsing strain inherent in a planar structure, can be relieved by puckering the ring. Rings larger than cyclopentane would have angle strain if they were planar. Consequently, the five-membered ring adopts non-planar puckered conformations whenever possible. Cyclopentane has very little angle strain (the angles of a pentagon are 108º), but its eclipsing strain would be large (about 10 kcal/mol) if it remained planar. Cyclobutane reduces some bond-eclipsing strain by folding (the out-of-plane dihedral angle is about 25º), but the total eclipsing and angle strain remains high. Cyclopropane also suffers substantial eclipsing strain, since all the carbon-carbon bonds are fully eclipsed. The 60º bond angles are much smaller than the optimum 109.5º angles of a normal tetrahedral carbon atom, and the resulting angle strain dramatically influences the chemical behavior of this cycloalkane. Although the customary line drawings of simple cycloalkanes are geometrical polygons, the actual shape of these compounds in most cases is very different.Ĭyclopropane is necessarily planar (flat), with the carbon atoms at the corners of an equilateral triangle.

How to draw boat conformation on chem draw