Topic 3: Stereochemistry Part 2: Conformation of Molecules

Question 1

5 properties of chiral molecules

Answer 1

Same atoms
Same connectivity
Different permanent geometries
Non-superimposable mirror images
No plane of symmetry

Question 2

Enantiomers

Answer 2

Stereoisomers that are non-superimposable mirror images
Chiral
Same molecular formula and connectivity
Different spatial arrangements
Identical physical and spectral properties but rotate plane polarised light in opposite directions

Question 3

Stereoisomers

Answer 3

Isomers that have different spatial arrangement but same order of atomic connectivity

Question 4

Enantioenriched

Answer 4

Mixture of 2 enantiomers where there is more of one than the other

Question 5

Enantiopure

Answer 5

Sample contains a single enantiomer

Question 6

Enantiomeric excess equation

Answer 6

ee (%) = [(R-S)/(R+S)] x 100

Question 7

R and S

Answer 7

Clockwise
Anticlockwise

Question 8

For a compound with n stereocentres, there can be up to … stereoisomers

Answer 8

2^n

Question 9

How can you take advantage of diastereoisomers having different chemical and physical properties to separate enantiomers

Answer 9

Chemically transform the mixture of enantiomers into new compounds that are diastereoisomers
Separate (e.g. column chromatography)
Convert separated diastereoisomers back into original enantiomers