Ch 3. Conformations and Stereochemistry

What is the lowest energy conformation?

anti

What is the highest energy conformation?

eclipsed

Which energy conformation has a dihedral angle of 60°?

gauche

Which conformation of cyclohexane is the most stable?

chair

Where should substituents be placed to reduce steric strain?

equatorial

Where should the bulkier substituent be placed in a chair conformation?

equatorial

What is a chiral center?

sp3 hybridized carbon atom with 4 unique substituents

What is the 2^n rule used for?

To predict the number of stereoisomers that exist for a given compound

Opposite configurations at all chiral centers.

stereoisomers

Opposite configurations at some, but not all, stereocenters

diastereomers

same molecular formula, but differ in the connectivity of their atoms,

constitutional / structural isomer

What molecules rotate plane polarized light?

chiral molecules

What molecules do not rotate plane polarized light?

racemic mixture, meso compound

What molecules are optically active?

chiral molecules

What molecules are not optically active?

racemic mixture, meso compound

are meso compounds chiral or achiral?

achiral

Configuration when higher priority groups on both carbons are on the same side of the double bond.

Z

Configuration when higher priority groups on both carbons are on the opposite side of the double bond.

E