CHEM 232 Exam Two April 5, 2010

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1 CEM 232 Exam Two April 5, 2010 Name (-1 pt) TA Name (-1 pt) UIN (-1 pt) Question 1 [Qualitative anking, 40 points] A significant amount of time has been devoted to describing the physical and chemical properties of ganic compounds including acidity, bond strength, boiling point, solubility, heat of combustion, confmation, constitution and reactivity. ank the molecules in each set below accding to the trends observed f the physical and chemical properties indicated. A. ank each of the following alkyl halides in der of increasing rate of S N 2 substitution (1 = slowest rate; 5 = fastest rate). (5 pts) B. 1,3-Dienes and dienophiles undergo Diels-Alder cycloaddition to fm cyclohexenes. ank the following diene/dienophile combinations in der of decreasing rate of reaction (1 = fastest reaction, 4 = slowest reaction). (4 pts) C. ank the rate of S N 1 substitution in each of the solvents below in increasing der (1 = slowest S N 1 reaction, 5 = fastest S N 1 reaction). (5 pts) C 2 2 (ε = 21) (ε = 33) (ε = 78) (ε = 9) (ε = 58) Page 1 of 8

2 CEM 232 Exam Two April 5, 2010 Name (-1 pt) TA Name (-1 pt) UIN (-1 pt) D. ank the following molecules in der of increasing number of chiral centers dipole moment (µ) (1 = lowest dipole moment, 4 = highest dipole moment). (5 pts) E. ank the following anions in der of decreasing leaving group ability (1 = best leaving group; 5 = poest leaving group). (5 pts) 3 C S 3 C S Based on your knowledge of the periodic table (see final page), rank each compound/anion in der of increasing nucleophilicity (1 = least nucleophilic; 5 = most nucleophilic) (5 pts) - Na + Se - Na + - Na + S - Na + S - Na G. ank the following molecules in der of increasing heat of combustion (1 = least exothermic, lowest comb, 6 = most exothermic, highest comb ). (6 pts) ank the following carbocations in der of decreasing stability (1 = most stable, 5 = least stable). (5 pts) Page 2 of 8

3 CEM 232 Exam Two April 5, 2010 Name (-1 pt) TA Name (-1 pt) UIN (-1 pt) Question 2 [Predict-the-Products, 50 points, 5 points each] Draw the maj ganic product(s) f each of the reaction schemes below. Indicate charged atoms. φnsted acid-base reactions, draw both conjugates. + NC heat CN single isomer CN Na N 3 (l) single isomer 1. Pd/CaC 3 lead acetate quinoline 1. t-buk 2. B 3 T, then 2 2 /Na 2. 2 light (hv) -78 C 2 x Ts Ts Na 2 S (S 2- anion) S C 9 18 S C 3 Ts C 3 S - Na + Et C 3 S C 3 2 C 3 C 3 Page 3 of 8

4 Question 3 [chanisms, 40 points] A. Draw a reasonable arrow-pushing mechanism f the following transfmation. (10 pts) B. the following first der nucleophilic substitution (S N 1) reaction, draw a reasonable arrow-pushing mechanism. Account f why this transfmation proceeds with 66% net inversion rather than racemization ( pts) Et, 2 + (S)-2-bromooctane (1) (S)-octan-2-ol (2) ()-octan-2-ol (3) 17% yield 83% yield Page 4 of 8

5 A. Draw a reasonable arrow-pushing mechanism f the following transfmation. (15 pts) N N 1. C C 3 Page 5 of 8

6 Question 4 [Synthesis, 40 points; points] Devise a synthesis f both target molecules (products) below. Write the fward synthesis from the reactant(s). Include all necessary conditions above/below the reaction arrow f each transfmation. Write out the product f each transfmation in your synthesis separately. You may write out a retrosynthetic analysis; however, only the fward synthesis will be graded. Me than one synthesis may be possible f each? Na, NaEt tert-buk 2 2? Ms Ts pyridine S 2 Na 2 S 4 Na + - N 2 S 2 2, Pd-CaC 3 lead acetate quinoline Page 6 of 8

7 Question 5 [Stereochemistry & Structure, 40 points] A. (i) Mark all the chirality centers in the structures of the naturally-occuring cell migration inhibit Moverastin (1), the anticancer agent puraquinonic acid (2) and the lipid-lowering drug Lipit (3) with an asterisk (*). (10 pts) (ii) Using the Cahn Ingold Prelog (CIP) priity rules, determine the absolute configuration and assign an S descript to each chirality center within molecules 1, 2, and 3. (14 pts) * S * * * * C N N * * Moverastin (1) (-)-Puraquinonic Acid (2) Lipit (3) B. Which of the following molecules are chiral, which are achiral?. (8 pts) C 2 achiral chiral achiral chiral C. What isomeric relationship do the following pairs of compounds have with each other? (12 pts) (a) and (c) and enantiomers enantiomers (b) and (d) and diastereomers confmers Page 7 of 8

8 Question 6 [unctional Groups, 30 points; 5 points each] Write the name f the principle functional group present in each molecule (e.g. ketone, alcohol, etc.). Do not write the IUPAC name common name f the molecule, just the functional group name. Names must be spelled crectly f credit. acid chlide aldehyde C allene enol N 2 nitro group N amine Page 8 of 8

Only five of the molecules below may be prepared as the sole product of allylic halogenation of the respective alkene. Circle those five.

Only five of the molecules below may be prepared as the sole product of allylic halogenation of the respective alkene. Circle those five. Chem 232 D. J. Wardrop wardropd@uic.edu Problem Set 6 Answers Question 1. nly five of the molecules below may be prepared as the sole product of allylic halogenation of the respective alkene. Circle those