Chiral

Question 1

Explain the term chiral

Answer 1

A chiral molecule is non-superimposable on its
mirror image. It has a carbon atom that has four different groups attached.

Question 2

What causes a difference in optical activity?

Answer 2

optically active - unequal mixture of enantiomers

not optically active - equimolar mixture of two enantiomers (racemic mixture)

Question 3

When an optically active isomer of 2-bromopropanoic acid is used in Stage 2, the resulting 2-hydroxypropanoic acid is also optically active. State and explain what this indicates about the mechanism of the first reaction in Stage 2.

Answer 3

• A racemic mixture is not formed
• (Some of the) reaction is SN2
• Nucleophile / OH− only attacks from one side of the
  molecule / from the opposite side to leaving group.

Question 4

What is the test for an aldehyde?
Carboxylic?

Answer 4

Fehlings/benedict = red/brown

carboxylic - phosphorus chloride = steamy fumes

Question 5

What is a racemic mixture?

Answer 5

conatins equal quantities of each enantiomer of a chiral compound.

Question 6

What are optical isomers?

Answer 6

rotate plane polarised light - optically active

Question 7

What are enantiomers?

Answer 7

mirror images of each other - non superimposed.