Devise a procedure for separating a mixture of the four stereoisomers of isoleucine into its four components: (+)-isoleucine, (-)-isoleucine, (+)-alloisoleucine, and (-2)-alloisoleucine (Problem 31). (Note: Alloisoleucine is much more soluble in 80% ethanol at all temperatures than is isoleucine.) 

Data From Problem 31.

The abbreviation allo means diastereomer in amino acid terms. Draw allo-l-isoleucine, and give it a systematic name.