(6 points) Naproxen (\"Aleve\") is a common over the counter anti- inflammatory

Question

(6 points) Naproxen ("Aleve") is a common over the counter anti- inflammatory drug. The S-enantiomer is effective, the R-enantiomer is not. The [aB of the S-enantiomer is+50 a) Is the S-enantiomer levorotatory or dextrorotatory? Na 0 HyCo sodium Naproxen b) What is the ee of a sample where the measured [a] is +25"? In a sample of Naproxen where the ee is 64% and the optical rotation in the (+) direction, what fraction (what percentage) of the sample is the desired S-enantiomer? c) (8 points) Four reaction energy profile diagrams (A -D) are given below.

Explanation / Answer

a) It is dextrorotatory that is it rotates the plane of polarized light clockwise Its positive specific rotation value is +ve denotes its dextrorotation.

b)%ee=100(specific rotation of sample)/specific rotation of a pure enantiomer

specific rotation of sample=[a]=+25o

specific rotation of a pure S- enantiomer=[a]D20=+50o

%ee=100(+25o/+50o)=50%

c)ee=64%

So, if there is an 64% excess of S-enantiomer .then the remaining 100-64=36% must be equal amount of R and S enantiomer.(18% each)

Thus % of S-enantiomer=64+18=82% of S-enantiomer

fraction of S-enantiomer=0.82

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