ed IR Correlation Taitl Experiment 10: Resolution of Racemic Ibuprofen and Cadap
ID: 589925 • Letter: E
Question
ed IR Correlation Taitl Experiment 10: Resolution of Racemic Ibuprofen and Cadaptnd hom XDetermination of Optical Purity (adapted from McCullagh, Jowrnal of Chemical Quession to be addressed by doing this experiment: How do we separate one another? enantiomer from Required Reading: Mohrig, Chapter 17, Sections 1-3 (pp. 240-248), "Optical Activity and Enantiomeric Analysis used, answers to pre-lab questions, and procedure. Before you come to lab: Prepare your prelab with introduction, safety data for the reagents to be BACKGROUND INFORMATION The ability to produce enantiomerically pure compounds is crucial to the fine chemicals industries (pharmaceuticals, agrochemicals, fragrances, ete). This ability is probably most important to the phamnaceutical industry, where approximately 80% of the drugs under pure methods - resolution and asymmetric synthesis. Resolution is the process in which the two enantiomers of a racemic mixture are separated. Asymmetric synthesis involves the use of s chiral reagent or catalyst to create a new optically active molecule. In this experiment, you will separate a racemic mixture of ibuprofen into its R and S enantiomers. Ibuprofen belongs to a class of pharmaceuticals called non-steroidal anti- inflammatories, or NSAIDs. It is the active ingredient in Motrin and Advil, along with their generic equivalents. It is primarily used for pain relief and fever reduction. Of the two enantiomers, only one, the (S)-(+)-enantiomer, has the desired pharmacological activity, while the R enantiomer is inactive. Since the R-enantiomer is not harmful, most commercial ibuprofen is sold as a racemic mixture, but recent research indicates that using only the S enantiomer might be beneficial, so several companies are developing methods to produce the enantiomerically pure form of ibuprofen and related compounds. The resolution you will be conducting works by temporarily converting the pair of enantiomers, which have identical physical properties, into a pair of diastereomers, with different physical properties, by using a single enantiomer of a second chiral compound (the resolving agent). Ibuprofen is a carboxylic acid, which will react with an amine to make an ammonium carboxylate salt: NHs (S,S) salt, insoluble in aqueous solution racemic ibuprofen (SH-Ha-phenylethylamine NH3 (R,S) salt, soluble in aqueous solution Experiment 10- ResolutionExplanation / Answer
Chiral resolution
Conclusions
3. Here we are separating S-Ibuprofen from racemic mixture using S-phenyl ethyl amine as the chiral resolving agent.
The resolving agent forms an water soluble salt with R-(-)-Ibuprofen. R-(-)-Ibuprofen is not required for drug activity. The aqueous solution conaining the salt of R-(-)-Ibuprofen (R,S) is neutralized with H2SO4. The resulting neutral R-(-)-Ibuprofen is insoluble in water and can be separated easily by filtration. The compound thus obtained is dried and melting point is checked for its puritiy.
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