Question

Name C341 Workshop Section Week 5 Workshop Questions terecisomers, RS enastiomeric xcess, IUPAC Key concepts: Provide the IUPAC name for each of the following molecules (Read pgs 566-68 (2d edn) concermning the priority of the OH group for pt b), molecalar representations 1. но * Approximately 50% of marketed drugs are sold as ficemic mixtures, while approximately 50% are enantiopure. Most of the biomolecules in living organisms are chiral so biochemistry happens in a chiral environment. As a result, the two enantiomers of a drug will interact with the body differently. One enantiomer may be pharmaceutically active and beneficial, while the other may be inactive or even harmful. For example, (R)-thalidomide is used to treat morning sickness, while (S)-thalidomide causes birth defects. The lack of oversight for the pharmaceutical industry exemplified by thalidomide led to the current drug approval process and the FDA. 2. To avoid unexpected biological activities, many chemists activcly develop cnantioselective syntheses to generate enantiopure molecules while others develop sovel separation techniques to retrieve the desired enantiomer from a racemic mixture. In 2004, Miyako et al reported a supported liquid membrane encapsulating surfactant-enzyme complex that enabled the resolution of racemic ibuprofen leading to an 91% enantiomeric excess of (+) (S)-ibuprofen (JACS, 2004, 126, 8622). a) Draw and label the absolute stereochemistry of the two enantiomers of ibuprofen. Ifthe optical rotation of pure (S-ibuprof n is +99", what was the optical rotation of the sample that had 91% ee? b) e) What percentage of the sample in part (b) is made up of each enantiomer?
1&2

Answer 1

(a) 3 - Brome - 2 - - 3 - methyl pentane. (b) 2 - Brome - 3 - methyl 1 - 01 (a) (b) ee/0 = [alpha]_mix/[alpha]_pure times 100 Is = alpha_mix/59 times 100 alpha_mix = 91 times 59/100 = + 53.69 degree c) Here 91% is pure (+) for we and 9% is recommit mixture (plusminus) Therefore Total (+) isomer = 91 + 9/2 = 95.5% and total (-) isomer = 9/2 = 4.5%