Chapter 6, Problem 6PP

PRACTICE PROBLEM 6.6

$S_{N}2$ reactions that involve substitution at a chirality center can be used to relate the configuration of one molecule to another, because we know the $S_{N}2$ reaction will occur with inversion.

(a) Illustrate how this is true by assigning R, S configurations to the 2-chlorobutane enantiomers based on the following data. [The configuration of (–)-2-butanol is given in Section 5.8C.]

(b) When enantiomerically pure (+)-2-chlorobutanc is allowed to react with potassium iodide in acetone in an $S_{N}2$ reaction, the 2-iodobutane that is produced has a minus optical rotation. What is the configuration of (–)-2-iodobucane? Of (+)-2-iodobucane?