Question

21. Answer ALL parts of this question. The anti-inflammatory agent, (S)-naproxen sodium salt has a specific rotation of +66º. The commercial preparation of the latter agent results in a mixture that has a 97% enantiomeric excess (ee). colo H3C0 (S)-naproxen sodium salt (a) Draw the R enantiomer of naproxen sodium salt. (1 mark) (b) What effect does the R enantiomer have on plane-polarized light? (1 mark) (c) What is the observed specific rotation of anti-inflammatory agent mixture? (4 marks) (d) What percentage of each enantiomer is obtained from the above commercial mixture? (2 marks) (e) Provide a reaction scheme for the formation of the (S)-naproxen sodium salt from “acidic" (S)-naproxen. (2 marks)

Answer 1

al Gulla ag Pro and Hin lop face so clockwise rotation gived s-configuration: S is po the R-leon enantiomes C# Osobre as it is bottom face so clockwise rotation gives R-isomer. W.CC 6) Pure s- isomer Incidient nas a specific roration of +66°c : ie; it rotate the Plane polarised light at 66° to the right (taking (4) en right) R- enantiomer show a specific rotation - 66° ie; it rotater the incidient plane polariped light 84-60° to the list. so tas The miau're in has 97% enantiomeric eneess that meano it 97% prines so entantion in excess (31 se 31 R, gired another 1.54.5 & 1.5-1. R) vrow, 15. s & 15% R enantiomes neutralises each other. 97% S will show the rotation for the misture. vrow, 100% pure scenantiomer gives +66 outation. 97% +66 797 100 e observed speific rolation in 464 1020 of the mixture. = +64.02° Yokston. In commercial preparation it has 97% enantiomesic miscuore yo (100-97)): -3.). is recemic ie; 2 s. i R? 3/2): ins. So S- d) Total s Total R = 97. + 372 = 312% = 98.575 = 1.57 R. ey 엠 0 Very dil. Nault Na 8H ONS acid +40 acid salt. Here the very dil Jraolt make the transformatim acid to salt dorot in a If conc. wast is used inen there will be posibilily of oker sicle reactions. strong and