_______________________________________
FINAL Name HOUR TEST
1. (7) A Haworth projection for the pyranose structure of a sugar is given below. a. (4) In the space provided to the left of the Haworth projection, draw the structure of the sugar as a Fischer projection in the standard arrangement with the most oxidized carbon at the top and the CH 2 OH at the bottom. b. (3) In the space provided to the right of the Haworth projection, draw the sugar as the chair structure of it's aanomer.
2. (20, 2 each) Below and on the next page is shown a collection of structures from classes of compounds which have been discussed during the second half of this semester. Some include additional important information in a caption. Each is designated with a large bold-face letter. Below is given a set of nine statements which may apply to one or more of the structures. Beside each of the statements given, write the letter corresponding to the structure that best fits that statement. An answer MAY be used more than once. Some will not be used at all. If there is more than one correct answer, you only need to give one.
Final Hour Test (b), Chemistry 302, Fall 2004, Page 1 of 5 pages
P a. This structure is that of an AB type nylon B c. This compound is a non-reducing
disaccharide.
E b. This compound is an alkaloid.. G d. This compound is an L ketose. S
f. This compound contains an anhydride formed from two monoesters of phosphoric acid.
K e. This compound is an AABB type polyester. A g. One of the sugars in this compound is an
an L aldopentose.
A h. This compound is reducing disaccharide in which the two
sugars are joined by b 166 O glycoside linkage.
L i. This polymer is based on a diamide of
carbonic acid (a urea).
R j. This compound includes an "anhydride" in which one
carbonyl oxygen has been replaced by an imine.
Final Hour Test (b), Chemistry 302, Fall 2004, Page 2 of 5 pages
3. (12, 3 each) In the spaces provided, write stereochemically correct Fischer projection structures for compounds having the indicated structural characteristics. NOTE: Each answer requires you to draw two or more structures. a. An appropriate D-aldohexose and the optically inactive product that it would form upon reduction with aqueous sodium borohydride (NaBH 4 / H2 O).
b. An appropriate L-aldotetrose and the optically active product that would form when it is treated with warm dilute nitric acid (HNO3 / H2 O / D).
c. A D-aldopentose of your choice and the two products that would form when it is treated with hydrogen cyanide containing a catalytic amount of potassium cyanide [H!C/N / K+ -C/N (cat. amt.)]
d. An L-aldohexose and the product it would form when treated with the following sequence of reagents: 1) NH2 !OH / alcohol / H2 O / pH 5; 2) [CH3 C(O)]2 O / CH3 C(O)- Na+ [acetic anhydride / sodium acetate]; 3) CH3 !O- Na+ / CH3 OH
Final Hour Test (b), Chemistry 302, Fall 2004, Page 3 of 5 pages
4. (17, the point value of each box is shown in the box) The alkylation, hydrolysis, and decarboxylation of a b-keto ester formed by a or Claisen Dieckmann condensation was among the important synthetic sequences that was discussed in the fourth unit of the course. The entire synthesis involves several mechanisms that have been introduced during the time you have been studying organic chemistry. Below is shown a sequence of steps that starts with a keto ester and leads to an alkylated ketone. The various mechanisms involved are exemplified by the sequence of steps shown below the reaction. In each box, write the structure of the intermediate that would be present at that point in the process. Be sure to show all formal charges.
Final Hour Test (b), Chemistry 302, Fall 2004, Page 4 of 5 pages
5. (9, 3 each) Below are shown three synthetic transformations, each requiring several steps. Below them are given six sequences of reagents, one of which would be expected to actually lead to each of the indicated products. In the space beside each transformation, write the letter corresponding to the sequence of reagents that would be expected to result in that transformation. NOTE: You are to choose your answer for a, b, and c from the same six sequences of reagents.
Final Hour Test (b), Chemistry 302, Fall 2004, Page 5 of 5 pages
6. (10) The aldol reaction accompanied by dehydration was another important synthetic reactions that was discussed in the fourth unit of the course. It can be used to make an a,b-unsaturated ketone from an aldehyde and a ketone so long as the aldehyde has no a-hydrogens. The mechanism of such a process is exemplified by the following reaction. In each box, write the structure of the intermediate that would be present at that point in the mechanism. Show all formal charges.
Final Hour Test (b), Chemistry 302, Fall 2004, Page 6 of 5 pages
(18, 3 each) In the spaces provided below, write stereochemically correct structures for compounds A - F. An optically active aldopentose, A, C5 H10 O5 , gave an optically active product, B, C5 H12 O5 , when it was treated with aqueous sodium borohydride. Reaction of A with hydroxylamine, NH 2 OH, at pH 5 converted it to C, C5 H11 NO5 . When compound C was allowed to react with acetic anhydride in the presence of sodium acetate and the resulting product was then treated with sodium methoxide in methanol, it was converted to D, C4 H8 O4 . Warming D with dilute nitric acid converted it to E, C4 H6 O6 , an optically active compound. Compound D could be synthesized starting with LFinal Hour Test (b), Chemistry 302, Fall 2004, Page 7 of 5 pages
glyceraldehyde for which the structure is given below. Reaction of L-glyceraldehyde with hydrogen cyanide in the presence of cyanide ion gave F, C4 H7 NO3 , and an isomer of F. Treating an aqueous acid solution of F with hydrogen in the presence of a palladium on barium sulfate catalyst converted it to D. Similar treatment of the isomer of F converted it to an isomer of D. It is NOT NECESSARY to show the structures of the isomers of D and F that are mentioned. A SUMMARY IS GIVEN BELOW.
Final Hour Test (b), Chemistry 302, Fall 2004, Page 8 of 5 pages