CHM136H1 Lecture Notes - Lecture 11: Cyclohexane Conformation, Cyclobutane, Pentagon

• School: UTSG
• Department: Chemistry
• Course: CHM136H1
• Professor: Clive Scott Browning, Ronald Kluger

Document Summary

4 kj/mol per eclipsed h-h interaction similar to a sin graph, with equal max and min points. Steric strain torsional: repulsion between bonds steric: repulsion between molecules themselves, for substituents (since h doesn"t have electron cloud around it that repels other electron clouds, it does not have steric strain) Anti-conformation of butane has no strain overall, since there is no repulsion between electrons of eclipsed bonds (staggered formation), and methyl groups are as far away from each other as possible. Gauche: no torsional strain, since it is still staggered; but methyl groups are too close together such that electron repulsion of the methyl group becomes important destabilized by 3. 8 kj/mol due to steric strain. Strains in organic chemistry lower energy = higher stability = higher proportion of molecules in this conformation. Since eclipsed non-polar single bonds are 4 kj/mol, the steric strain of eclipsed ch3-ch3 is 7 kj/ mol.