Recovery of (+) (S) Ibuprofen From The Salt Procedure {This is a reaction) Trans

Question

Recovery of (+) (S) Ibuprofen From The Salt Procedure {This is a reaction) Transfer the salt to a clean 50 mL beaker equipped with a stir bar. Add approximately 25 mL of 2M H2S04. Heat the solution gently on the hotplate while stirring until all of the crystals dissolve and leave behind thick oily droplets suspended in the top of the solution. Workup for the recovery of (+) (S) Ibuprofen Remove the stir bar, rinse it with acetone, and return it to your TA. Meanwhile, allow the mixture to cool. Transfer the mixture to a reparatory funnel and extract the aqueous layer with approximately 15 mL of ethyl ether three times. The ethyl ether layer (organic) will be on top. Combine the organic layers from the three extractions and wash with approximately 15 mL of water in the reparatory funnel. Discard the aqueous layer from the wash with water then wash the organic layer with approximately 15 mL of saturated sodium chloride solution in the reparatory funnel. Transfer the final organic layer to a tared oeaker with a Doiling chip. Heat in a water bath to remove the ether and recover the resolved ibuprofen. When all the ether is gone put the beaker in an ice bath. The product will probably be a semi solid oily mess. Scratch it with a glass rod to get the product to crystallize. Mass the beaker and obtain the mass of the product. Obtain a melting point of your product and compare to the literature value. Obtain an FTIR of your product. Add 100 mg of your product to a 10 mL volumetric flask. Dilute to the mark with 95% ethanol. If you do not have 100 mg use less and adjust your concentration calculation. Your TA will run the polarimeter. The polarimeter will give you a rotation, you will need to use the formula to relate your observed rotation to absolute alpha. This will give you your observed absolute alpha. Once you have the observed absolute alpha calculate enantiomeric excess and optical purity. % enantiomeric excess (% ee) is (observed absolute alpha/literature absolute alpha) x 100%. You should have the literature absolute alDha in your pre-lab. Optical purity is higher than %ee. Optical purity = ((100 - %ee) 12) 4 %ee. Calculate % yield of recovered s-(+) Ibuprofen from original 15 tablets of Ibuprofen.

Explanation / Answer

Optical rottaion an percentage recovery.

Since you have not provided data for the isolated ibuprofen sample we would write procedure and data can be fed accordingly to get final result.

For optical rotation

specifc rotation of sample = observed rotation/concentration of solution (g/ml) x path length (dm)

here,

concentration of solution = 0.1 g/10 ml = 0.01 g/ml

From this specific rotation we would calculate %ee

optical purity of sample = specific rotation of sample x 100/specific rotation of pure enantiomer

pure S-(+)-ibuprofen has a rotation = +54.5 degrees

This would give % of ee

remaining = 100 - optical purity = would give racemic percentage

%enantiomer of other enantiomer = racemic %/2

Percentage of S-(+)-enantiomer (%ee) = optical purity% (as calculated before) + racemic/2

Percentage of R-(-)-enantiomer = racemic/2

14. Percentage recovery

From 1 tablet = x g

From 15 tablet = 15x g

Percent recovery = (15x) x 100/mass of 15 tablets

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