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Unformatted text preview: Name CHEM235 – Organic Chemistry II Spring 2008 Mid‐Term Examination #3 Instructor: James Poole This examination is worth 100 points of a final potential total of 700 points for this course, and consists of 8 questions plus a bonus question. You are required to answer all of the eight questions, but you may not be required to answer all parts of a given question, so read the question carefully. For questions where you are not required to answer all parts, you should clearly indicate which parts you wish to have graded. Question 1 (8 points). Predict the outcome of the following reaction, and explain your answer in terms of the relevant reaction mechanism. You must include the reaction mechanism in your answer, and you may employ any other illustrations or structures to illustrate your answer. KCN/HCN O H2O/THF Question 2 Name (12 points). Predict the outcome of the following reaction, and explain your answer in terms of the relevant reaction mechanism. You must include the reaction mechanism in your answer, and you may employ any other illustrations or structures to illustrate your answer. CH3CH2NH2 H2O/EtOH, pH 5 O Question 3 Name (8 points). Explain what is meant by the following terms. You may provide examples as part of your answer an ylide (a) (b) a protecting group Question 4 (8 points). Rank the following compounds (a) In order of increasing acidity (most acidic = 1, least acidic = 4) O2N COOH (H3C)2N COOH COOH Cl COOH (b) In order of increasing basicity (most basic =1, least basic = 4) O H3CO NH2 NH2 NH2 NH2 Question 5 1) NaH SH 2) CH3CH2CH2Br Name (21 points). Predict the outcome(s) of seven of the following thirteen reactions, including any stereo‐ or regio‐chemical outcomes. NaNO2/HCl NH2 0oC O (CH3)2NH EtOH/H2O, pH=5 O HO H /H2O
+ OH O H 1) CH3MgBr/ether 2) H+/H2O 1) NaN3/THF I 2) LiAlH4/ether 3) H+/H2O mCPBA S CH2Cl2, 0oC 1) nBu-Li/hexane P(C6H5)3 Br 2) O N2 Cl + OH CH3I NH2 NaHCO3 ∆ N(CH3)3 HO O CrO3 EtOH/H2O/H+ N2 BF4 ∆ Question 6 O Name (15 points). Provide a systematic name for three of the following five structures COOH H N O Br O O SCH3 CN F Question 7 (13 points). Briefly describe the differences between SN1 and SN2 mechanisms: you may use mechanisms, structures or diagrams to help illustrate your answer. Name Question 8 (15 points). Draw the structures corresponding to three of the five following names: N‐ethyl‐N‐methyl 4‐oxopentanamide tert‐butyl (R)‐3‐methylhexanoate (1R,2S)‐2‐methylcyclohexanecarbonyl chloride (S)‐3‐chlorocyclopent‐1‐encarbonitrile Acetic ((R)‐2‐methylhexanoic) anhydride BONUS (8 points). Predict the outcome of this hitherto unseen reaction, and propose a feasible mechanism for the formation of the product O + 2 CH3SH dil. H+ ...
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