Optical Isomers

Question 1

What happens to plane polarised light as it travels through an SN1 product?

Answer 1

Nothing changes because a racemixture forms so it doesn’t rotate the light.

Question 2

What happens to plane polarised light as it travels through an SN2 product?

Answer 2

The light is rotated because the nucleophile can only attack from one direction so no optical isomers form. (No racemixture)

Question 3

Define chiral center.

Answer 3

Carbon atom with four different groups bonded around it, so there’s no line of symmetry

Question 4

Define optical isomer.

Answer 4

Molecules have the same molecular formula but different spatial arrangement of atoms

Question 5

Define racemate.

Answer 5

Optical isomers are produced as a pair of enantiomers in a 1:1 ratio and doesn’t rotate plane polarised light

Question 6

Which nucleophilic substitution reaction do tertiary haloalkanes prefer?

Answer 6

SN1

Question 7

Which nucleophilic substitution reaction do primary haloalkanes prefer?

Answer 7

SN2

Question 8

Compare differences of using ethyl chloride to make an ester instead of carboxylic acid.

Answer 8

• Reaction is irreversible unlike carboxylic acid
• Hydrogen chloride is the by-product rather than water
• The reaction is really fast and occurs at room temp so an acid catalyst isn’t needed

Question 9

Do alkanes only have pi bonds or sigma bonds?

Answer 9

They only have pi bonds

Question 10

Why are alkenes susceptible to attack from electrophiles?

Answer 10

The carbon double bond is an area of high electron density

Question 11

What is produces when an aldehyde reacts with hydrogen cyanide

Answer 11

A hydroxynitrile ( -CHOHCN)