Question

b) The quinine isolated from this reacti pe isolated from this reaction was found to have a specific rotation of 135° (c=1, CHC13). Following a chiral resolution the specific rotation was found to be ali = -108° (c = 1, CHC13). The specific rotation of the desired enantiomer is (alk = -117° (c = 1, CHC13). Calculate the enantiomeric composition of quinine before and after the chiral resolution. Show your work. HINT: Found specific rotation = [a]. (X.) + [a]. (X_), where (X_) = (1 - (x2) % (+)-enantiomer and % (-)-enantiomer before chiral resolution - % (+)-enantiomer and % (-)-enantiomer after chiral resolution -

There is no structure.

Answer 1

Quinine isolated = +35° specific rotation But E(mixture of C) 46) isomer) of ene mie ) - Specific rotation of something a pure enantiomer Specific restabeer of (-)-enaalivaien = 1179

ee = 35 117 0.2999 0.2999 %.eez 29.91010 of (t) isomer +35° is specific rotation Here; (-) isomer: Desired isomer (mention in question) finding (+) 4 (-) isomer x + (x+29.9) = 100 2n = 70.085 x= 35.04% 6 isomer = 35.04% (A isomer = 64.95% Before Resolution After chiral Resolution ht; specific rotation = -108° ee - Specific Srotation Sample (mi xture) " " pune enartioner = 108 0.9230 hole = 92.30%. finding (+)4t) isomer x+ (x+92.30) = 100 x=3.85% → ) isomer = 3.851%. After (-) isomer = 96.15% resolution Thus the composition of quinine sample was calculated using enantiomer extes and specific rotation concept. 21