Referring to either representation of the boat conformation of cyclohexane, desc

Question

Referring to either representation of the boat conformation of cyclohexane, describe two structural features which make this conformation differ in energy from more stable conformations of cyclohexane. Hydrogens are not drawn in for the second structure.

Referring to either representation of the boat conformation of cyclohexane, describe two structural features which make this conformation differ in energy from more stable conformations of cyclohexane. Hydrogens are not drawn in for the second structure. H H H H

Explanation / Answer

ANSWER=

1...BOAT STRUCTURE OF CYCLOHEXANE HAVE TWO FLAG [C1 &C4 CARBON] HYDROGEN BECOMES NEAR WHICH CAUSE FEEL HIGH REPULSION FORCE HIGH ENERGY LESS STABLE

2...BOND STRAIN BETWEEN[ C2& C3 AS WELL C2&C6] CARBON SIGMA ]ARE MAKE IT UNSTABLE..

A planar structure for cyclohexane is clearly improbable. The bond angles would necessarily be 120º, 10.5º larger than the ideal tetrahedral angle. Also, every carbon-carbon bond in such a structure would be eclipsed. The resulting angle and eclipsing strains would severely destabilize this structure. 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. This boat structure still has two eclipsed bonds and severe steric crowding of two hydrogen atoms on the "bow" and "stern" of the boat. This steric crowding is often called steric hindrance. By twisting the boat conformation, the steric hindrance can be partially relieved, but the twist-boat conformer still retains some of the strains that characterize the boat conformer. Finally, by lifting one carbon above the ring plane and the other below the plane, a relatively strain-free chair conformer is formed. This is the predominant structure adopted by molecules of cyclohexane.

An energy diagram for these conformational interconversions is drawn below. The activation energy for the chair-chair conversion is due chiefly to a high energy twist-chair form (TC), in which significant angle and eclipsing strain are present. A facile twist-boat (TB)-boat (B) equilibrium intervenes as one chair conformer (C) changes to the other.

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