1 CHE 202/204 Spring 2011 Midterm Exam-3 April 16, 2011 Name (Please Print): Person #: CHE (202 or 204): Section (B & C): Signature: Problem Maximum points Actual points 1. 48 2. 16 3. 12 4. 10 5. 10 6. 12 7. 10 8. 12 9. (extra credit) 10 Total maximum 140 Your total2 1. Circle the correct answer: (48 pts) (1) When a carbonyl group is part of a conjugated π-network, the C=O bond is: a. longer than that in a nonconjugated system. b. shorter than that in a nonconjugated system. c. the same as that in a nonconjugated system. e. none of the above. (2) Compared to ketones, aldehydes react in rates in nucleophilic addition reactions a. the same b. slower c. faster d. different (3) When the carbonyl group of a ketone is protonated: a. the resulting species can react with both weak and strong electrophile(s). b. the resulting species can react with both weak and strong nucleophile(s). c. the resulting species only reacts with strong acid. d. the resulting species does not react at all. (4) The reagent which converts a carbonyl group of a ketone into a methylene group is: a. Na, NH3, CH3CH2OH. b. NaBH4, CH3CH2OH. d. BH3-THF. e. LiAlH4. (5) Compared to an alkene C=C bond, a carbonyl double bond has: a. higher polarity. b. lower polarity. c. the same polarity. d. no polarity. (6) What reagent can be used to convert a carboxylic acid to a ketone? a. water. b. NaOH. c. LiAlH4. d. an organolithium (RLi).3 (7) Carboxylic acids boil at considerably higher temperatures than do alcohols, ketones, or aldehydes of similar molecular weights. This is because they: a. have a greater oxygen content. b. are more acidic. c. form stable hydrogen-bonded dimers. d. are hydrophobic. (8) Nucleophilic acyl substitution is a reaction involving: a. aldehydes. b. ketones. b. carboxylic acids and their derivatives. d. any compounds containing the carbonyl group. (9) Typically, esters will hydrolyze under conditions than amides. a. stronger b. more dilute c. less rigorous e. milder (10) Amides are much less basic than amines because: a. the carbonyl group donates electrons by resonance. b. the carbonyl group withdraws electrons by resonance. c. the nitrogen does not have a lone pair of electrons. d. the nitrogen has a full positive charge. e. amides do not contain nitrogen. (11) Nitriles (R-CN) are considered to be carboxylic acid derivatives because: a. they share the same general structure with the other derivatves. b. they also contain the carbonyl group. c. they are always prepared from esters. d. they can be converted into both amide and carboxylic acids. (12) The reactivity of carboxylic acid derivatives decreases as leaving group becomes a. smaller b. larger c. less basic d. more basic4 2. Provide the structure of the major product in reactions shown below. (16 pts) (1) (1) CH3LI (2 equiv.)(2) H3O+COOH (2) (1) LiAlH4(2) H3O+OO (3) CH3NH2!OO (4) O+ HOCH2CH2OHH+ (5) CH3OHOOO5 3. Provide a detailed, stepwise mechanism for the reaction below. (12 pts) (1) CH3MgBr(2) H3O+HOCH3OH 4. How would you use 13C NMR spectroscopy to distinguish between the following compounds? (10 pts) OCCH3CH2OCH2CH3OCCH3CH2CH2CH3AB6 5. Complete the following reactions by showing the structures of either the reactants or product(s), along with the reaction conditions. (10) (1) O+CH3CH=PPh3 (2) OO 6. Propose a synthetic sequence to convert compound A into B. You may use other necessary reagents. (12 pts) CHOOCHOAB 7. Rank the compounds in each set in order of decreasing acidity. (10 pts)7 COOHCOOH COOH COOHNO2CN BrAB C D(a)(b)COOHCOOH COOH COOHBr Br BrAB C DBr BrBrOrder of decreasing acidity:Order of decreasing acidity: 8. Suggest the way to effect the following conversion. You may use other necessary reagents. (12 pts) CH3NOCH3H8 9. Extra credit. Treatment of amide A with LiAlH4, followed by acidic aqueous work-up, draw the structure of compound B. Also show the structure of the intermediate for the reaction that leads to C from B. (10 pts) O OH3CNH2OLiAlH4, (CH3CH2)2O H+,