1 Organic Chemistry I (230-001) Examination III November 24, 2004 Name (PRINT LEGIBLY): Please provide clear and concise answers to all of the following questions. Use equations and/or drawings to support your answers where appropriate. Please answer questions in the area provided, the back of an exam page or on the clearly labeled spare page. Problem Score 1. (a-c) /12 2. (a-f) /30 3. (a-b) /10 4. /14 5. /14 6. (a-e) /20 Total /100 PLEASE OBSERVE THE FOLLOWING. 1) Write LARGE and LEGIBLY. If I can’t read what you write, I can’t give you full or partial credit. 2) Read each question carefully before answering. If you don’t answer the question I posed, you will not receive credit.2 1. (4 pts each, 12 pts) (a) Arrange the compounds (1-3) below in order of increasing acidity for the indicated hydrogen. Briefly explain your reasoning. EtO OEtO OHO OHOEtO OH123 (b) Circle the more acidic of the pair of compounds below, and provide a short reason for your answer. HHOHHO3 (c) Which of the following lists the compounds in order of decreasing acidity? Circle your answer. a. H2O > HC≡CH > NH3 > CH3CH3 b. HC≡CH > H2O > NH3 > CH3CH3 c. CH3CH3 > HC≡CH > NH3 > H2O d. NH3 > H2O > CH3CH3 > HC≡CH e. H2O > NH3 > HC≡CH > CH3CH3 2. (5 pts. each, 30 pts. total) Draw the major product of each of the following reactions. If no reaction is expected to occur, write “No reaction.” Be sure to indicate the stereochemistry of the product, if appropriate. A mixture of configurations should be indicated with a squiggly bond ( ) to one of the groups attached to the stereogenic C atom. (a) CH2H3CCBrHCH3H3C(H2C)3C C:- Na+ (Hint: consider the pKa of HC≡CH)4 (b) OH + NaIH2O/ acetone (c) (H3C)3COTsCH3HCH3COOH (d) BrHCl25 ˚C5 (e) CH3CH2OHCH3CH2O-Na+BrH3C (f) CH3OTsHCH3COO-Na+DMF 3. (a, 5 pts) Rank molecules A-E (below) according to how fast they undergo E2 reaction mechanism: Br Br BrBrBrAB C DE SLOWEST: < < < < FASTEST6 (b, 5 pts) For either the fastest or the slowest molecule to undergo E2 reaction mechanism, give a brief explanation for your answer above. 4. (14 pts) Which alkyl halide and what conditions should be used to prepare the following alkene in good yield by E2 elimination reaction mechanism? Briefly explain reasoning. No credit will be given without a valid explanation. CH27 5. (14 pts) Ethers can be prepared by SN2 reaction of alkoxide ions with alkyl halides. Which of the two possible routes shown below would you advise Joe Greenhorn to use to prepare cyclohexyl methyl ether in high yield? Briefly explain your reasoning. No credit will be given without a valid explanation. O: -ICH3—O: -OCH3::+ CH3I::+or(A)(B)8 6. (20 pts) Answer the following question in reference to the reaction energy diagrams below. The labeled points on the reaction energy diagrams are either energies or chemical species, depending on the sentence. a. ______ might be a catalytic intermediate or even a carbocation. b. The energy difference between ____________ might determine the rate of an SN2 reaction. c. The energy difference between ____________ might determine the ratio of product to starting material of an E1 reaction. d. The Hammond postulate states that D is most similar in structure to ______. e. Factors that destabilize ______ will decrease the rate of an E2 reaction.9 SPARE
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