25.1 - Optical Isomerism

Question 1

Drawing CH3CH(NH2)COOH

Answer 1

Question 2

How to draw optical isomers

Answer 2

a solid line is a bond in the same plane as the paper

a dotted line is a bond receding behind the plane of the paper(this can also be hatched or shaded wedges)

a solid wedge is a bond coming out of the paper

Question 3

How to identify chiral centres:

Answer 3

• whether the particular carbon is bonded to four different atoms or group of atoms to make it chiral
• whether the carbon is bonded to two of the same group of atoms and therefore cannot be chiral

Question 4

What can the rotation of plane polarised light used to do?

Answer 4

determine the identity of an optical isomers of a single substance

Question 5

If an enantiomers rotate what is it referred to as?

Answer 5

optically active

Question 6

How do you differentiate the isomers?

Answer 6

• using (+) and (-)
• d and l
• D and L (dextro-enantiomer and laevo-enantiomer
• R and S

Question 7

Difference between 2 enantiomers

Answer 7

• one of the enantiomers rotates plane polarised light in a clockwise manner
• the other in an anticlockwise manner

Question 8

Properties of enantiomers

Answer 8

• identical chemical properties
• differ in ability to rotate plane polarised light

Question 9

What type of images are enantiomers?

Answer 9

non-superimposable mirror image

Question 10

What are enantiomers?

Answer 10

compounds with a chiral centre which have 2 optical centres

Question 11

What is a chiral carbon/chiral centre?

Answer 11

a carbon that has 4 different atoms or groups of atoms attached to it

Question 12

Two types of stereoisomerism

Answer 12

• geometrical
• optical

Question 13

What are stereoisomers?

Answer 13

molecules that have the same structural formula but atoms have a different spatial arrangement in space