CHM242H5 Lecture Notes - Lecture 4: Methyl Group, Butane, Steric Effects
Document Summary
Conformations of cycloalkanes: occurs widely in nature, has neither angle strain (~109 ) nor torsional strain (staggered, adopts chair conformation, chair conformation: strain-free, 3d. Alternate conformation of cyclohexane: boat cyclohexane: bears a slight resemblance to a boat, no angle strain, large number of eclipsing interactions, twist-boat conformation: somewhat more stable than a pure boat conformation, nearly free of angle strain. Chair cyclohexane has six: axial hydrogens perpendicular to the ring (point up or down, equatorial hydrogens near the plane of the ring (kind of horizontal) Each carbon atom in cyclohexane has one axial and one equatorial hydrogen. Each face of the ring has three axial and three equatorial hydrogens in an alternating arrangement. Ring-flip: interconversion of chair conformations, resulting in the exchange of axial and equatorial positions: upon flip, don"t (cid:272)hange fa(cid:272)e, onl(cid:455) positions, cyclohexane often flips in nature. One confirmation will never go to 100%, there will always be a little of the unstable conformation present.
