S.11.215FEKEYV4 - Name_ Page 1 S.11.215FE I. (36 points) A....

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Name_____________________________ I. (36 points) Page 1 S.11.215FE A. Back when I was an undergraduate, I worked on the following method for forming aldehydes that uses light alone (and no additional reagents) to break apart Molecule A to form the products shown. The result is an oxidation to form an aldehyde and regenerate the anthraquinone starting material. ( J. Org. Chem ., 60 , 6853.) O O O O O O O OH O O O H Molecule A visible light This method of aldehyde formation has several advantages over the oxidation methods you have studied in Chemistry 215. Briefly explain two (2) of these advantages. O O OH O O Br K 2 CO 3 + anthraquinone starting material aldehyde product advantage #1 advantage #2 1) No additional reactants, no chromium or other toxic reagents needed, therefore "greener". 2) No additional reagents required, so may be cheaper. 3) Oxidation stops cleanly at the aldehyde and doesn't form the carboxylic acid. 4) Oxidation can be performed in the presence of acid sensitive groups, unlike the acidic chromium oxidations discussed in class. 5) The anthraquinone (starting material) is regenerated and could be recovered and recycled. 12 6 pts each + B. The most stable conformation of most aldopyranoses is one in which the largest group (the CH 2 OH group) is equitorial . However, D-idopyranose exists primarily in a conformation with an axial CH 2 OH group. ( Note: make sure your chairs are beautifully drawn and axial/equitorial bonds are unambiguous. If we can't tell what you've drawn, it will be marked wrong.) H HO OH H H HO OH H CH 2 OH O H D-idose 1. Draw the chair conformation of ! - D-idopyranose that has the CH 2 OH axial . O (S) (R) HO H OH H HO OH H H H (S) (R) OH (R) (R) (S) (S) O (R) H HO H OH H H OH H HO HO 2. Draw the chair conformation of ! - D-idopyranose that has the CH 2 OH equitorial . 3. Briefly explain why the conformation you drew in I.B.1. above (with CH 2 OH axial ) is the more stable chair conformation.
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S.11.215FEKEYV4 - Name_ Page 1 S.11.215FE I. (36 points) A....

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