CHEM 233 Makeup Exam: Chirality, Equilibria, and Organic Reactions, Exams of Organic Chemistry

Download CHEM 233 Makeup Exam: Chirality, Equilibria, and Organic Reactions and more Exams Organic Chemistry in PDF only on Docsity! CHEM 233 - Prof. Mazzocchi Name Exam 3 - Makeup Lab Section December 12, 2001 Lab T.A. _ In addition to this face page there are six (6) pages to this exam and nine questions. Count the pages. Put your name on EVERY page. Answer all questions. No one may leave the exam before 2:45. 1. 2. 3. 4. 5. 6. 7. 8. 9. TOTAL ACADEMIC INTEGRITY: Violations of the Code of Academic Integrity will not be tolerated. Suspected cases will be reported immediately to the appropriate authorities. All work submitted for grading (quizzes, exams, lab reports) must be the original work of the student whose name appears on the work. Group or pair projects, approved by the professor, must have all participants names on the work with the indication that students were instructed to work in pairs or groups. The same work cannot be submitted for credit in two different courses or from semester to semester in the same course (e.g., repeated lab exercises) without the written permission of all instructors involved. Falsification of excuses for missed work will be treated as cases of academic dishonesty. The standard penalty for violations of the Code of Academic Integrity is a grade of "XF".______ ________________ _______ __________ Name 1. For each of the following pairs of drawings, identify the molecules as chiral or achiral and tell whether each pair represents molecules that are enantiomers, diastereomers, or identical. (21 points total) (CH3)3C Relationship of the pair (CH3)3C a) This molecule is (chiral, achiral) This molecule is (chiral, achiral) OH b) H- CH3CH2 - -CH2CH3 H OH OH CH3CH2 - H- H OH CH2CH3 This molecule is (chiral, achiral) This molecule is (chiral, achiral) HO. c) H H C"M" H C' 4 '• H This molecule is (chiral, achiral) This molecule is (chiral, achiral) Each question (a, b and c) requires three answers - chirality of each structure (2 pts. each) and the relation of the two molecules in the pair to each other (3 pts. each). -1- 4. a) Label ail of the stereogenic centers in the compounds below with an asterisk *. (20 points) O NH Streptimidone progesterone b) For the molecule progesterone indicate how many possible isomers there are. 5. For the following questions, MATCH each definition to a term from the list below. (15 points) A. racemates B. stereogenic center C. chirality D. diastereomers E. enantiomers F. meso compounds is the property of "handedness," the property of an object that causes it to be nonsuperimposable on its mirror image are stereoisomers that are not mirror images is an atom in a molecule that is bonded to four different atoms or groups of atoms are molecules which contain stereogenic centers and a plane of symmetry are 50:50 mixtures of non-superimposable mirror images 6. Give the R or S configuration of the carbons indicated below. (13 points) CH2NH2 a) Is the 1,3 dimethylcyclohexane chiral or achiral? .4- 7. THINK! All questions below concern the reaction shown, (a - d = 4 pts each, e = 8 pts) (24 points total) CH3CH2C— CH3 Br CH3CH2C— CH3 I CH3CH2OH/H2O 8:2 + CH3CH2OH/H2O 8:2 74% substituion products *- + 25 26% elimination products 74% substituion products ——**" + 25° 26% elimination products When either of the two substrates above (the bromide or the iodide) are reacted with a mixture of 80% ethanol - 20% water at 25°, the same ratio of substitution-elimination products is obtained. a) By what mechanism does ELIMINATION most likely occur in these compounds under these conditions? ___________________ b) By what mechanism does SUBSTITUTION most likely occur in these compounds under these conditions? ___________________ c) Which substrate undergoes substitution faster (the bromide or the iodide)? ____________ d) Which substrate undergoes elimination faster? _______________________ e) Draw the structure of the two elimination products formed. -5- 8. Identify which of the following are aromatic. (8 points) b CH, H3C g 9. Show the product of the following reactions. Be sure to indicate stereochemisty. (10 points) a) CH3 Br H C———cf- H Br CH3CH2O' Na+ (excess) CH3OH b) C(CH3) 3 S'Na4 Cl -6-