337exam_answers_Exam 2 answers

337exam_answers_Exam 2 answers - CHEM 337 SPRING 2008 EXAM...

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Unformatted text preview: CHEM 337 * SPRING 2008 * EXAM 2 NAME STUDENT # 1. Suggest a synthesis for 1,3,5-t1is(dimethylamino)—2,4,6-trinitrobenzene fiom anillne. Use the following reagents in any order: AlBl‘3, H2804, HgPO;é Brz, HN(CH3)2, H20, NaNOz, fuming nitric acid (nitric acid in which extra N02 gas have been dissolved). NH2 NHZ N02 Brz AlBr3 Br Br (H3C)2 (CH3)2 ‘———* OQN N02 r N(CH3)2 . 1. NaN02 2. Ham}. HN(CH3)2 H2304 H20 N02 Br Br H2804 Br Br fuming HNO3 <———————. r Br 2. (Solomons. In 1884 Perkin achieved a successful synthesis of cyclopropanecarboxylic acid from sodiomalonic ester and 1,2-dibromoethane. Outline the reactions involved in this synthesis. BrCHZCHzBr + NaOCsz + CH2(C02C2H5)2 —————> BI’CHQCHZBT + NaOCQH5 + CH2(COQCZH5)2 O2(32H5 BrCHZCHz O202Hs ——|——O" K+ ? (1) OH‘, H20, heat t (2) H30+ 020sz (2) heat, —CO2 02H . 0202H5 3 . p-Chloronitrobenzene was allowed to react with sodium 2,6—di—tert— butylphenoxide with the intention of preparing the diphenylether below. The product was not the ether pictured but rather an isomer with a phenolic hydrogen. The reaction the ensued could best be described as a reaction. Which fits the blank. t—bu Q_o_Q_Noz t-bu b C) 3N1 d) SEAT e) E2 4. ' " Why is it possible for 2,2’—dihydroxy-1,1’-binaphthyl to exist in enantiomeric forms in solution at room temperature? ; a) rotation about the 0-0 single bond is hindered b) in its ground state the molecules has neither a plane of symmetry, a center of inversion, nor an improper rotation axis 6) the naphthyl groups can not lie in a common plane @ll of the above e) none of the above 5. .r Which is least acidic? a) picric acid (2,4,6-trinitrophenol) b) the first excited state of phenol c) H2804 d benzoic acid a enzoic acid anhydride 6. " Which of the following is the strongest Bronst - base? a c ( ) (b) H < ) H ‘ H i1 g: ‘ «KL»b a" {if H H 211 a 7. Which of the following is an intermediate for the basic hydrolysis of methyl ethanoate? O 3 ‘3 320 best (a) (b) (c) ,9 (d) 9 @ 9H r in CH3“ C“ Q?" CH3“ C” 0”“ CH3 $3 0‘“ CH3“ CE” 0‘“ 9 H OH @032 8 Which of the following is an intermediate formed during the acidic hydrolysis of acetamide? 0 e (a) (b) 0 0 ii @a . _ ii 8E3“ iC" NH? CH3“ C“ Wig OH 9; 9 ‘ ‘ Ethyl crotonate, CH3CH=CHCOOCzH5, reacts with diethyl oxalate, CszOOCCOOCsz to form a Claisen-type condensation product: H H CZH5OC—CCHZCH=CHCOCZH5 Write a detailed mechanism for the formation of this compound. a, Key step is to recognize that ethyl crotonate can undergo gamma hydrogen abstraction. (0 n p —--—~ 0sz 10 H } What is the major product of each of the following reactions? H I m or + H (:COOH H20H 0 H3 or H [ ‘0 + H o o 0 0 ' CH gt N g CH MOE <~—> , = a: = :2 macaw 3 ’ 3 cold / 11. f ' ‘ Professor Anthony Arduengo III has prepared some interesting compounds that are surprisingly stable. For instance, the carbocation (a) can be deprotonated to give compound (b) C21H24N2, which is an air stable crystalline compounds. What is so unusual about compound (b)? It has a divalent carbon atom. Can you make sense of this compound by drawing resonance structures? Not really. *—» The lone pair of electrons indicated is in a single orbital. What kind of orbital is it in? sigma orbital, spz‘ 12. Finish the following sentences. Use only one sentence. “An orbital is ...a solution to Schrddinger’s wave equation (for one electron). “An orbital is not ...a region of space, a volume, a probability. 13a. "‘ ‘ “’ When excess anthranilic acid was treated with HZSO4/NaN02 in the presence of C60, the following mass spectrum was obtained of the reaction mixture. What happened? NH 2 HZSO4/NaN02 OOH anthranilic acid (excess) mafia-efng 13b. (Sci? a an, 25 3313:} When 2-bromo-1,3-dimethylbenzene is treated with sodium amide (NaNHz) in liquid ammonia, no substitution takes place. This result can be interpreted as providing evidence for the eliminate—addition mechanism in the reaction of sodium amide with bromobenzene. Explain. No ortho hydrogens for basic abstraction initiating the benzyne synthesis. ...
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337exam_answers_Exam 2 answers - CHEM 337 SPRING 2008 EXAM...

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