Answer key for Mid-term 2 exam Form A(1)

CHEM 2420 ---Organic Chemistry II Fall 2015 Mid-Exam No. 2: Chapter 17-18 (Form A) Name: ÿ'ÿ,ÿt ÿ-,4 Instructions: A) Please print your name on the line above. B) Make sure you have 12 pages. C) Good luck! Question Score Multiple choice /80 Free response Bonus Total /20 /5 /105 1 IP aÿ.,o e Section 1. Multiple Choice (80 points) Bubble the choice that best completes each phrase and/or answers the question on the Scantron sheet provided. Answers written in this section of the exam will NOT be graded (20 X 4 = 80 points). 1. What is the IUPAC name of the following compound? a. 5-methylhexanoic acid @ (E)-5-methylhex-2-enoic acid c. (Z)-5-methylhex-2-enoic acid d. 5-methylhex-2-enoic acid . Which combination(s) of alkyl bromide and carbonyl compound can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the carbonyl compound? OH CH3Br (CH3) 2CHBr CH3CH2Br (CH3)2CHBr O O O O 1 2 3 4 a. only 1 and2 b. only 3 and 4 @ only 2 and 3 d. only 1, 2 and 3 3. What is the major organic product obtained from the following reaction? 21P a g e 4 H H2S04 "ÿ©J -'-OH ÿ©J ÿOH a. I C. 3 d. 4 4. What is the correct assignment of the names of the following functional groups? NOH 1 NCH3 NH2 N-NH2 a, 1 = imine; 2 = amine; 3 = hydrazone; 4 = oxime b. 1 = hydrazone; 2 = amine; 3 = imine; 4 = oxime 1 = oxime; 2 - imine; 3 = amine; 4 = hydrazone d. 1 = imine; 2 = hydrazone; 3 = oxime; 4 = amine 5. Which of the following is the best description of the mechanism of Claisen condensation (the basemediated reaction between two esters to form 13-ketoester)? a. concerted bimolecular substitution ), nucleophilic addition followebdy elimination c, elimination followed by nucleophilic addition d. electrophilic addition followed by rearrangement 6. What is the major organic product obtained from the following reaction? O . ÿjÿÿ 1. LiA2I. HH204 a. 3-heptene BIPa,,e,:: b. heptane . (E)-h2e-phtaenp°tel ne 7. Give the product for the following reaction. CHÿCHÿ...ÿC......CI 1. 2 CH3MgCI 0II 2. HÿO, H÷ OH.,.. Hÿ CHz--ÿ;ÿ O H / CH, B) CH2CH:, I CH3CHÿ--C--O H 1C:Hÿ CHÿ I CHÿ,--C--O H C) I D) CHÿ CHÿ C H,ÿ I CHÿCH2--C--O H I CH2CHÿ 8. What is the relationship between the following two structures? "" (D O • : 0•• : a. tautomers b. constitutional isomers, but not tautomers resonance structures stereoisomers 9. What is the major organic product obtained from the following reaction? 4lPage o H + O O a. 1 b. 2 tl " yd. 4 4 10. What is the major organic product of the following aldol addition? O& OH" .L? I, m, 0 OH OH ÿH o IV. g. OH 0 OH 0 C) III D) IV E) V 5[Page 11. What is the ÿ organic product of the following reaction? O O O + C C OCK3 IV, 0 0 ,,CHÿOCH3 m, 0 OH --CH3 o C) III D) IV E) v 12, o o OCH2CH3 What is the major organic product obtained from the following reaction?, ............................. -,,, i///" O "' O O " II II OCH2QH3 1.CH3CHzoHNaOOH2CH3 I ,,....... O 2J ÿ'ÿ j// 2. Br 3. H3O÷ o o o a. 1 61Page 13, Give the major product for the following reaction. 0II .2CHs OH@ excess BF.2 A) c) CHa D) aorta BI Br 14. What is the major organic product obtained from the following reaction (hint: LDA is a very strong base which can deprotonate the a-hydrogen of ketones to foÿm eorrespondingaaÿolates)? 1.LDA,-78 °C '1 O 2 O o 3. H30+ A H a. 1 C2 . 3 d. 4 7!Page 15, What is the major organic product obtained from the following reaction? 1. NaOCH2CHs CH3CH2OH 2. HsO+ OCH2CH3 2 O O H2CH3 O O OCH2CH3 4 a, 1 b. 2 16,/ÿÿe major/ ÿ organic producto obtained from the following reaction? 1. NaOCH2CH3 I ÿÿ CH3CH2OH CH3CH20 " ÿ 'l "ÿ OCH2CH3 2. H3O+ H2CH3 :CH3 0 0 }H2CH3 O 8]Page a. 1 b. 2 d. 4 17. What is the major organic product obtained from the fbllowing reaction? 0 0 0 C) ÿ1ÿaOCH2CH3 H3CH20._H 3. H3O+ O 2 0 4 0 a. 1 d. 4 18. What is the major organic product obtained from the following sequence of reactions? O O CH3CH20ÿOCH2CH3 1. NaOH, H20 1. NaOCH2CH3 1. NaOCH2CH3 2. H3O+ CH3OH CH3CH2OH CH3CH2OH 3. A H2SO4 0 " 2. CH31 2. CH3CH2Br 3. H30+ 3. H30+ O O OCH3 ÿJÿOCH2CH2CH3 O OCH3 9]Page 12 C. 3 d. 4 19. How many different aldols (13-hydroxyaldehydes), including constitutional isomers and stereoisomers, are formed upon treatment of 2-methylpropanal with base? C, d. 1234 20. What is the major organic product obtained from the following reaction? O r 1 0 0 4 a. 1 b. 2 D lOIPage Section 2. Free Response (20 points) Write CLEARLY in complete sentences o1" show all work if the problem calls for it. Remember to show all lone pair electrons if drawing a mechanism. ° Mechanism. Draw the mechanism by which the following reaction occurs. Be sure to show curved arrows to indicate the movement of electrons as well as all lone pair electrons. (2 X 6 = 12 points) a° O OH 1. CH3MgBr 2. H3O+ v CH3 4 b, o 0 © ©O lllPage 2. Synthesis. Provide all reactants, reagents, and intermediate products for preparation of the following product from starting material (8 points). O O OCH2CH3 Me O . h O Bonus (5 points): Draw the other THREE resonance structures of the following enolate. O o H3CÿO ,.frail H3C" ÿO ,,@ :Q : 0 /-ÿ c L J2t5 ,,@ 0 :02 12I Paoeÿ,