Chapter 5.12, Problem 31P

The amino acid $\left(S\right)\text{-alanine}$ has the physical characteristics listed under the structure.

(S)-alanine

$\left[\text{α}\right]=+8.5$

$\text{mp}=297°\text{C}$

a. What is the melting point of $\left(R\right)\text{-alanine}$?

b. How does the melting point of a racemic mixture of $\left(R\right)\text{-}\text{and}\left(S\right)\text{-alanine}$ compare to the melting point of $\left(S\right)\text{-alanine}$?

c. What is the specific rotation of $\left(R\right)\text{-alanine}$, recorded under the same conditions as the reported rotation of $\left(S\right)\text{-alanine}$?

d. What is the optical rotation of a racemic mixture of $\left(R\right)\text{-}\text{and}\left(S\right)\text{-alanine}$?

e. Label each of the following as optically active or inactive: a solution of pure $\left(S\right)\text{-alanine}$; an equal mixture of $\left(R\right)\text{-}\text{and}\left(S\right)\text{-alanine}$; a solution that contains $75\%\left(S\right)\text{-}\text{and}25\%\left(R\right)\text{-alanine}$.