Problem_Set_4_solution - Chem 3580 - Spring 2009 Problem...

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Chem 3580 - Spring 2009 Problem Set #4 - Solution 1. O S O O A Tosylation does not affect the asymmetric carbon. Nucleophilic substitution occurs at the S. O O B This is S N 2 rection. Acetate attacks from the backside leading to inversion of configuration. OH Reduction by LiAlH 4 involves attack by H at the acyl carbon. Bond between asymmetric carbon and and oxygen remains intact. 2. The following factors have to be considered: (a) Stability of the ester based on resonance: OR O OR O Electron donation of alkyl groups increases with increasing number of alkyl groups. The more electron donating R becomes the more important the resonance hybrid on the right becomes and the more stable the structure becomes. Increasing order of stability: alkyl = CH 3 < CH 3 CH 2 < CH(CH 3 ) 2 < C(CH 3 ) 3 . => Decreasing order of relative rate: alkyl = CH 3 > CH 3 CH 2 > CH(CH 3 ) 2 > C(CH 3 ) 3 . (b) Electropositive character of the carbonyl group: The more electropositive, the more reactive. Electropositive character decreases with increasing electron donation. Hence the order of decreasing
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This note was uploaded on 09/07/2009 for the course CHEM 2183 taught by Professor Jonnjardarson during the Spring '09 term at Cornell University (Engineering School).

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Problem_Set_4_solution - Chem 3580 - Spring 2009 Problem...

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