stereochemistry

H/H eclipsed energy cost:

Torsional strain: 4 KJ/mol

H/CH3 eclipsed energy cost:

Torsional strain: 6 KJ/mol

H3C/CH3 eclipsed energy cost:

Torsional strain + steric interaction: 11 Kj/mol

CH3/CH3 exlipsed energy cost:

Steric interaction: 3.8 KJ/mol

The Baeyer strain theory

it was thought that rings were flat. It states that larger rings would be very highly
strained, as their bond angles would be very different from the
optimum 109.5°

It turns out that cycloalkanes with more than three C atoms in the
ring are not flat molecules. They are:

puckered to reduce strain

what is the most stable cycloalkane?

cyclohexane

heat of combustion vs stability

The less heat released, the more stable

axial and equatorial rings

axial is up down, equatorial is left right

Which is more stable- axial or equatorial?

equatorial bc bulky groups on it cause less strain

diastereomers

isomers that aren’t mirror images. ex. cis and trans are diastereomers

number of stereoisomers

2^n (n=# of assymetric centers)