I am a teaching and research professor since 2002.
Show that a thermal suprafacial addition is symmetry allowed in a (4 + 2] cycloaddition by using the HOMO of the alkene and the LUMO of the diene.
If the two stereogenic centers of a compound are $R,S$ in configuration, what are the $R,S$ assignments for its enantiomer and two diastereomers?
(a) Label the four stereogenic centers in sorbitol as $R$ or $S.$ (b) How are sorbitol and $\textbf{A}$ related? (c) How are sorbitol and $\textbf{B}$ related?
Draw all possible stereoisomers for each compound. Label pairs of enantiomers and diastereomers.
The amino acid ($S$)-alanine has the physical characteristics listed under the structure.a. What is the melting point of ($R$)-alanine?b. How does the melting point of a racemic mixture of ($R$)- and ($S$)-alanine compare to the melting point of ($S$)-alanine?c. What is the specific rotation of ($R$)-alanine, recorded under the same conditions as the reported rotation of ($S$)-alanine?d. What is the optical rotation of a racemic mixture of ($R$)- and ($S$)-alanine?e. Label each of the following as optically active or inactive: a solution of pure ($S$)-alanine; an equal mixture of ($R$)- and ($S$)-alanine; a solution that contains 75% ($S$)- and 25% ($R$)-alanine.
What is the $ee$ for each of the following mixtures of enantiomers $\textbf{A}$ and $\textbf{B}$?a. 95% $\textbf{A}$ and 5% $\textbf{B}$ b. 85% $\textbf{A}$ and 15% $\textbf{B}$