Chair, Boat and Envelope Conformations

Question 1

The Chair conformation of a 6 membered ring

Answer 1

• 1,3 diaxial are unfavourable
• a big group in an axial position will try to go into equatorial position
• staggered

Question 2

The Boat conformation of a 6 membered ring

Answer 2

• steric clashes, a lot of electron repulsion
• more unstable than chair
• chair goes through boat to reach other chair conformation
• 1,4 diaxial interactions - unpleasant
• eclipsed

Question 3

The Envelope conformation of a 5 membered ring

Answer 3

• almost eclipsed - not the best
• base more eclipsed than the side
• oxygen two lone pairs causes repulsion
• oxygen can be out of the plane or in the plane
• unfavourable, 5 membered rings more unstable than 6 membered