ORGANIC CHEMISTRY Chapter 5 5.8b Racemic forms and enantiomeric Excess(外消旋体及对映体过量百分率) moles of one enantiomer-moles of other enantiomer 100% total moles of both enantiomers observed specific rotation 1009 specific rotation of the pure enantiomer R]_[S ×100% R]+[S] o ee= o enantiomeric excess Department of Chemistry, Xiamen UniversityORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 5 5.8B Racemic forms and Enantiomeric Excess (外消旋体及对映体过量百分率) moles of one enantiomer − moles of other enantiomer total moles of both enantiomers = observed specific rotation specific rotation of the pure enantiomer % ee = × 100% × 100% = [R]－[S] [R]＋[S] × 100% % ee = % enantiomeric excess