Fall 2001 Test 3

Fall 2001 Test 3 - Chem 227 Fall EUR]! Test 3 Dr. Wells...

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Unformatted text preview: Chem 227 Fall EUR]! Test 3 Dr. Wells Name _ _ _ _ _ 3-3:.1140- .- . .. , l'Ll-‘w _I_ II:_. I II Ii Iii-hull II. Hill: -__1I,| r L. . 3mm - 5F1'I!.'|F~i‘i11'5."i. .11.}? ' null 1 . Which umupnund heimr is vinyl u'nhmdu 'E' 2 . The best name for compound 3 is A. 1,2-diethy1-1-propene B. 1-methylcyclobuty1ene C. 1,2-diethy1butene I D Q3) trans-3-methy1—3-hexene E. (Z)—1 ,2-diethy1-1 -propene 3 The best name for compound 4 is A. (Z)-1,1,3-trimethy1-1—propene 7\ ® 4-ethy1-3-methy1-3-heptene C. 1-methylcycloheptene D. 4-ethyl-5-methy1-4-heptene E. 1,2-diethyl—1-methy1—2-propy1ethene The best name for the compound 5 is A. 4-octyne ’ (E 3—hexyne C. (E)-2-butyne D. cis-2-bromyne 5 E. (Z)-3-hexyne 5 . Which alkyl halide substrate would you expect to undergo SNl reaction with CN' most rapidly ? ® (CH3) c1 / r . A B. (CH3):CBr L v \S bco’l’ l («U\ “:9 Dru kp‘ C. (CH3)3CCI D. (CH3)3CF . 7 E. they would all react at the same rate C ‘9 (“9“ h“ f r 6 . Formation of alkenes by hydrogenation of alkynes with platinum is difficult because ® alkanes are formed B. the two pi bonds of the alkyne can not bond to the metal surface C. cation formation is limited to unstable 10 carbocations D. skeletal rearrangement is more likely E. alkyne hydrogens are more acidic Cycloheptyne has been observed at low temperature, but decomposes upon warming to room temperature because A. torsional strain is large 6) angle strain is large 3 C. the dipole moment decreases D. sp2 carbons are never stable at room temperature E. cycloalkynes are not stable regardless of size The basis of the Hofmann rule is A. formation of the more stable alkene B. formation of the least strained ring C. formation of the most stable carbocation D. planar molecules or ions will be attacked with equal frequency fiom either side (5 steric bulk directs reactants The basis of the Markovnikov rule is A. formation of the more stable alkene B. formation of the least strained ring © formation of the most stable carbocation D. planar molecules or ions will be attacked with equal frequency from either side E. steric bulk directs reactants 1 0 . 2,3-dimethyl-2-butene is more stable than propene because of _ A. acidity B. sterics © electronics D. ionics E. covalance 1 1 Alkanide migrations will occur. A. in strained alkynes B. only in newman' projections C. in gem-dihalides CD to create a more stable carbocation E. in vic-dihalides 1 2 . Catalysts work by (19 decreasing the free energy of activation (AG‘) B. lowering the free energy of the reactants (G°,eac,m) H C. lowering the free energy of the products (G°pmdm) D. decreasing the free energy difference between the products and reactants (AG°) E. inverting every other stereocenter Consider the plot for an SN2 reaction on the right for questions 13 and 14 The activation energy for this SN2 reaction is . ® 2 kcal/mol B. 6 kcal/mol C. 9 kcal/mol D. 13 kcal/mol 1 4 . The transition state is labeled by A. x Q 1 reaction conrdi -.-- D. It is not labeled in this plot l l 9 'I" 5 3 2 D .-I C 2 M U Ad. v Q U E E) F.) U . I.—.. 4.. |—| Check out the weird-wild reaction sequence below for questions 15 - l7. H C 1)Na(s)inNH3(1) H2 1) 03 TC——-——————> 15 —- 16 ___> 17 C HBr i ) 3 Pal/Cams 2) Zn/HZO CH3 1 5 . Compound 15 is most likely. Br Br I | H H H—c—c—H \ _ / I l CH3—CEC— CH3 CH3—CE C—NH2 /C— C\ CH3 H CH3 H 1 6 . Compound 16 is most likely & >C=C\‘ /c=c\ H/C\ /C\H CH3 H CH3 ens CH3 H /C=C\ A G) C CH3 D CH3 1 Compound 17 is most likely. o H H H H ll: \C/ \C/ \C/O\C/ TH (|)H / \ — CH H / \ A, 3 CH3/ \H CH3 \H H/ CH3 CH3 C=C—CH3 A B c D 1 8 . The major product of the reaction below is _. CH< /“ HBS /"=C\ H H 63 1 9 . The major product of the reaction below is _. _ lH HBr / perox1des H H ll 2 0 . The major product of the reaction below is _. CH3 C 1) 0804 k :2) NaHSO3 21 . The major product of the reaction below is _. CH3 H \ , KMnO4 H/C—C\ Cold,di1 ' H C 2 2 . The major product of the reaction below is _. 1) O3 2) H20 CH3— CE 0" CH3 5 D A “F3 I? 0513 H (,3— H—c—c—H H Br llgr 1'1 C CIiI3 IiI D CH3 ]l[ H—c r]:- H—fiI—(f—I Br Br H H (‘9 at ‘F 3' Cfih 1? H— ?“ (E‘H H——- C— (ID—H H Br 1'31. H C‘ “F3 1.1 D Cab It H—$—C— I-I— —— -—H l f 0—0 H H Hf]?3 l1 H B. CH; H _ H _ C_ 1i anH (4/ \0 CC) ell-[3 Iil D. (Huh ’1‘ H_?_?_H EFT-VII OH OH H H A fifth t H 3- cal H __ __ C_ IE 13:41.04 6/ \0 C. . Q C 3 D‘ C 3 1: H—-—$—-$—H H—j‘: + + H20 OH OH 0 {5 A. CH3 H3 B- | $ CH CH H—‘f—‘f—H ‘c—c’ 3 0—0 0” \\O c. C513 $H3 if CH3/K OH OH Consider the reaction of butylbromide with F‘ ion in dimethylamine for questions 23 - 24 CH3CH2CH2CH2Br + F' ------ --> CH3CH2CH2CH2F + Br“ (reaction 1) 2 3 . What effect on the rate would result fi'om doubling the concentrations of F‘ ion ? A. no effect (33 rate would double C. t uld lid 1 g D. it: aguld ingrgase by a factor of 4 («in f; )2, CNK 3 E. rate would increase by a factor of 6 24 . What effect on the rate of reaction 1 would result from switching from dimethylamine to dimethylformamide as solvent ? (M if A. no effect f n 3(\L 0‘ Cris N é rate would decrease / H / rate would increase / o C/ D. impossible to predict; must be determined by experiment \C/ \CHa /N\ / H3C CH3 H ._ dimethylamine dimethylfonInamide Consider the reaction sequences below. Identify compounds 30 - 31 for questions 25 - 26. CH3—CEC—H m 25 IHB‘, 26 peroxides 2 5 . Compound 25 is C In] l|3r CH3—bC—H I CH3— «3— C—H CH 3— C:' '—-H 11 B _ C_ _ , I r CH3 C H Br H CH3—C:C3 BI‘ q A B C D E 2 6 . Compound 26 is D H Br CH3—C=C—I-][ I l ll I CH 3— C— C—H CH3— F j:-_H Br CH 3— C: C—H LL B c ® E 2 7 . SN2 reactions are most likely to occur when A. bulky bases are used B. high temperatures are used C. concentrated sulfuric acid AND high temperatures are used Q.) primary alkylhalide substrates are used E. tertiary alkylhalide substrates are used 2 8 . SN2 rates are in aprotic solvents because the A. faster nucleophile is charged ® faster nucleophile is not caged A. slower nucleophile precipitates B. slower nucleophile is protonated E. unchanged nature of the solvent is unimportant in SN2 reactions 29 . SNl reactions can lead to racemic products because A. polar solvents are used B. protic solvents are used , C. tertiary alkylhalide substrates are used P D. high temperatures are used / @ a carbocation is formed 30 . Good leaving groups have A. conjugate acids with a large pKa B. lots of lone pairs / x5 6,) 2. l Lax/(k7 j fa ap a C) conjugate acids with a small pKa "‘ as J, l 7 _/ D. no lone pairs r“ V E. at least one SIllfilI atom F K“ O E L— l 5 3 1 . Which of the following statements is most accurate ? A. nucleophilicity never tracks basicity X Y B. SNl reaction rated depend on the concentration of the nucleophile X C. SN2 reactions lead to scalemic products K 3 (E intermediates live longer than transition states I/ E. hydrogenated oils are good for you x ...
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Fall 2001 Test 3 - Chem 227 Fall EUR]! Test 3 Dr. Wells...

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