Carbonyl compounds: optical isomers

Question 1

What are stereoisomers?

Answer 1

Same structural formula but different arrangement of atoms in space

Question 2

what type of isomers are optical isomers?

Answer 2

stereoisomers

Question 3

What is a chiral carbon?

Answer 3

a carbon with 4 different groups around it

Question 4

Define optical isomerism

Answer 4

Two non-superimposable mirror image structures.

Question 5

Optical isomers are optically active, what does this mean?

Answer 5

They rotate plane polarised light, one enantiomer rotates it clockwise whilst the other rotates it anticlockwise

Question 6

what is a racemate?

Answer 6

contains equal quantities of each enantiomer of an optically active compound

Question 7

Why don’t racemates show any optical activity?

Answer 7

The two enantiomers cancel each other’s light-rotating effect

Question 8

why do chemists react two a achiral things together?

Answer 8

To get a racemic mixture of a chiral product - since 2 molecules reacting have an equal chance of forming each of the enantiomers

Question 9

reaction of propanal with acidified potassium cyanide

Answer 9

Because the C=O is planar, there is an equal chance of CN nucleophile attacking from either of the the directions, so an equal amount of each enantiomer will form, you get a racemic mixture