McMurry (kap.5,8)

Question 1

What is a racemate/racemic mixture? (+-)

Answer 1

an equal mix of the dextrorotatory and levorotatory forms.

Racemates show no optical rotation because the (-) of one enantiomer cancels the (+) of the other enantiomer.

Question 2

What happens then a racemic mixture of (+) and (-) reacts with a single enantiomer of R-configurated molecule?

Answer 2

magine you have a racemic mixture of (R)- and (S)-lactic acid reacting with a single enantiomer of a chiral amine (R)-amine:

(R)-lactic acid reacts with (R)-amine, forming one diastereomer. (R,R salt)

(S)-lactic acid reacts with (R)-amine, forming a different diastereomer. (S,R salt).

These two diastereomers can now be separated due to their distinct properties, even though they originated from a racemic mixture.

Question 3

does the formation of these new diastereomers have the same properties?

Answer 3

When a racemic mixture reacts with a single enantiomer, the reaction leads to the formation of diastereomers.

These diastereomers can then be separated based on their different physical and chemical properties, unlike enantiomers, which are identical in an achiral environment.

Easy to separate by crystallization or other means.