25.2 - Racemic Mixtures

Question 1

What is the net optical activity of a mixture? When does this happen?

Answer 1

it’s the net effect of the movement of the plane polarised light rotating either clockwise or anti-clockwise

only happens when there’s an uneven mixture of each enantiomer

Question 2

What does the term optically active mean?

Answer 2

this is when there’s an uneven mixture of each enantiomer and this means that there’s a net rotation of mixture

Question 3

What is a racemic mixture?

Answer 3

A mixture in which there are equal amounts of enantiomers present in the solution

Question 4

Is a racemic mixture optically active?

Answer 4

it is optically inactive as the enantiomers cancel each others effects and the plane of polarised light doesn’t change

Question 5

What are the uses of racemic mixtures in the pharmaceutical industry?

Answer 5

• it is easier to produce synthetic drugs that are racemic mixtures than producing one enantiomer of the drug
• 88% of drugs are sold as racemic mixtures

Question 6

What are enantiopure compounds?

Answer 6

a drug that only contains one enantiomer

Question 7

Why is sometimes worthwhile to separate the enantiomers despite it being expensive and time-consuming? (2):

Answer 7

• the other entantiomer is harmful
• the drug is expensive to synthesise, no wastage of materials and resources to produce a drug that’s only 50% effective

Question 8

Story of thalidomide

Answer 8

a drug that eased morning sickness for mothers but instead it caused major birth defects within newborns - due to other enantiomer present within thalidomide