Isomerism and stereochemistry Flashcards
(8 cards)
1
Q
Structural isomers
A
Molecules w/ same molecular formula but differ in which atoms are bonded
2
Q
Structural isomers: shared characteristics?
A
- V. different physical properties
- Differ in melting/boiling points and chemical properties
3
Q
Conformational isomers
A
Molecules that are interchanged by rotation about a single bond
4
Q
Types of conformers and their relative energies
A
- Eclipsed has highest energies
- Gauch has less energy than eclipsed
- Anti conformation has the lowest
(Staggered conformers = gauch and anti)
5
Q
What is a conformers relative energy a result of
A
The level of stereoelectric (steric) hindrance
6
Q
What is the difference in energy between eclipsed and staggered conformers of ethane?
A
12 kJmol-1
7
Q
Conformational analysis of hexane
A
- Most hydrocarbon ring systems exhibit degrees of ring strain, except hexane
- Strain free because it adopts a CHAIR CONFORMATION
8
Q
Characteristics of a chair conformation
A
- Eclipsing is completely prevented
- bond angles are all nearly tetrahedral
- Have equitorial and axial branches
