(2S,3S,)-TARTARIC ACID, HOOCCH(OH)CH(OH)COOH HAS AN OPTICALACTIVITY OF -12 DEGRE
ID: 689949 • Letter: #
Question
(2S,3S,)-TARTARIC ACID, HOOCCH(OH)CH(OH)COOH HAS AN OPTICALACTIVITY OF -12 DEGREES AND THE MP OF 170. A.)WHAT IS THE ABSOLUTE CONFIGURATION, SPECIFICROTATION(OPTICAL ACTIVITY) AND THE MELTING POINT OF ITSENANTIOMER? B.) IS THE ENANTIOMER DESTROROTATORY OR LEROROTATORY? WRITETHE CHEMICAL STRUCTUE OF THIS ENANTIOMER? A.)WHAT IS THE ABSOLUTE CONFIGURATION, SPECIFICROTATION(OPTICAL ACTIVITY) AND THE MELTING POINT OF ITSENANTIOMER? B.) IS THE ENANTIOMER DESTROROTATORY OR LEROROTATORY? WRITETHE CHEMICAL STRUCTUE OF THIS ENANTIOMER?Explanation / Answer
The diagram program isn't working but your molecule has the alcoholgroups in the middle of the four carbon chain, the structure youneed has both alcohols as wedges (this is your +12). Itsenantiomer, dashes (the one your professor gave you to solve theproblem with -12) So the (2S, 3S) enantiomer has -12 optical activity, the enantiomer(2R, 3R) then has the exact opposite +12 (this is its specificrotation). Enantiomers have IDENTICAL physical properties, sothe melting point is the same for the (2R, 3R) 170. Sincethis enantiomer (2R, 3R) is +12, the + confers clockwise rotationand is dextrorotatory (counterclockwise, "-", levorotatory). Below is the structure. I think this is often made morecomplicated than it really is-- racemic structures of a pair ofenantiomers just rotate light in opposite directions. Forexample, if you get an equal mixture 50:50, the mixture is racemic,and no optical activity will be observed--- because the +12 and the-12 have cancelled one another out. Another trick whendrawing these is the enantiomer of a structure will have ALL itschiral centers flipped. So (XR, YS) has the enantiomer (XS,YR); diastereomers would only flip one of those chiral centers. +12, (2R, 3R) enantiomer of tartaric acid
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