2006Midterm2card001solutions

2006Midterm2card001solutions - Chemistry 266 Midterm Test 2...

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Unformatted text preview: Chemistry 266 Midterm Test 2 November 16, 2006 Instructions: 1. On the computer card, fill in the best choice A, B, C or D to answer each of the 20 questions that follow. Fill in only one answer for each question. 2. There is 1 mark for a correct answer and 0 marks for an incorrect or missing answer. Total marks possible = 20. 3. Under ID number, put your ID number. 4. Under section number, LEAVE BLANK 5. Under card number or test master, put 001. 0. Put your name and course number on the right. 7. Calculators and/or molecular models may be used by individual students but may not be shared around during the examination period. 8. You must return this examination paper with your name and ID number filled in at the end of the exam. 9. Only the answers marked on the computer card will be counted (regardless of what you may have marked on this question paper/exam). (18) (1) Noble IA Gases 1 2 H He 1.008 (2) KEY (13) (14) (15) (16) (17) 4.003 Hydrogen "A lllA IVA VA VIA VlIA Helium Atomic Number SYMBOL 13 Al 26.98 Aluminum 22.99 24.31 Sodium Magnesi (3) (4) (5) (6) (7) (3) (9) (10) (11) (12) 35.45 39.95 IIIB NB VB VIB VIIB VIIIB VIIIB VIIIB IB IIB Chlorine Argon 39.10 Polassrum CaIcrum Scandium a 37 38 39 40 Rb Sr Y Zr 85.47 87.62 88.91 Rubidium Stromiul Yttrium 197.0 2006 Gold Mercury Bismuth Polonium Astan‘ne 105 106 107 108 109 Unp Unh Uns Uno Une (262) (263) (264) (265) (266) Francium Radium 1. For the following compounds, the order of decreasing Bronsted acidity, from most acidic to least acidic, is: OH OH OH Latch h, M g Y n/‘uUU- ) . f) 5 n and r3. . C. 41- . No2 J 1 2 3 :1 fl L :1 f C. ,) L38. ’— ‘ I )krixi") . A 1>2>3 link ‘1 am) it . 1 H \7 B“ 3 > 2 > 1 \/ I L k" <92>1>3 '1'- LL? » 3>1>2 _,..M_ _. b_ , at.) \/ {5 '0 A solution of salicylic acid (1 mole) in one litre of ethanol (CH3CH20H) is treated with 1 mole ol‘NaOH. The major anion in solution after reaction is best described as: as: 0 it s: gut—Nag: ‘ LC/ 0“ H Ll e _ A o . OH \13 COOH / c009 (V g a hag; 5 @COOH \ I - t \ l G) salicylic acid B OCHZCH3 D O A solution of 1 mole of propyne in 1 litre of ethanol is treated with 1 mole of sodium ethoxide and then with 1 mole of 1-bromobutane. The major organic product(s) will be: , ,Qumste ; {out a: tLiz-f-‘ffi“=i“ .57..“ / _ ARV“? “2w ‘ __ NaOCH20H3 WEI. 9 t \L - "T H3C-C:C-H CH CH OH - .k M ' 1 3 2 ' ’ I 13 (Whack A HsC-CEC-CHchzCHZCHe, Elam/W w oat B CH3CHZOCHZC_H2CH2CH3 d l7” 5‘“, 'L C 1-butene La. L, m\/\ D E—2—butene 4. Which of the following molecules would have the lowest heat of hydrogenation? AM /\/\\/\ W M Q B > C, D mo'fl." gob“, - it" Mia-1'7"— \ ) 2 Ought) luwtjl \k‘z‘”+-.6Jb kick! a 5. Reaction ol‘rrans- l -chloro—2-ethylcyclohexane with NaOCHzCH3 gives the following compound as the major product: ” iv - CHZCHS C CHZCH3 OCHzCHg . 63:) CHZCHQ D CHchs III;;/{C! . “I” r\ .i ' l l‘ : : WOCHZCHS i' !\ t " ELLE if"? C'fir‘xcr1r- .1? My“ 6. In a polar, aprotic solvent such as dimethyl sulfoxide, CH38(O)CH3, the order of nucleophilicity for the halide anions from most nucleophilic to least nucleophilic is: ll l? T2 A 1’ > Br‘ > C1' > F' J n a A fiftmlgcl 6” l ® F'>C1'>Br'>1' (“11mm 53 V M ...-.KL€.\"> “ll-1’ ’(l C Br->C1->F->1' -- n ochTWLCL-T/ l)“ L “1 “W D F‘> Br'>c1'>1' l0...LJ-;L.cl3 7. Which of the following alkenes will the major product of acid—catalyzed dehydration of the following alcohol? t {2.3- 5. .; Fem-r ataxia-Mi . § l A C (1-) Oil 1 ‘3}. OH B 6):) {1/ '2’ l "3 ’ 8. The following molecule is treated with sodium thiophenoxide, NaSPh, in ethanol. The relative rates of reaction at the sites shown, from most reactive to least reactive, are: \0 ’wxol‘l' Hatfl‘kp-fi 2 I} 1 Br MIL Br 9. The following molecules are subjected to solvolysis (SNl reaction) in acetic (ethanoic) acid. The expected relative rates of reactions, from most reactive to least reactive, are: CH Br he :1} L_ (ix/lb rc-Jt'mt 2 CHZBr CHZBr 2-H. 5 {Chi};- -.-f1.t-_ .-; i? :3 i) i ‘ l n F: ‘ OCH3 i l l . 1 2 3 t“ W l i _ Q) l > 2 > 3 i l‘. g B 1 > 3 > 2 ‘ I U/ C 3 > 2 > 1 eff g (Reba-“4U t” 3' l1 Li. D 2 > 3 > 1 ‘-. .10, Rank the following molecules in terms of the relative reaction rates of 8N2 reaction, from highest to lowest: Mint is“. rs ‘> iii-i 7 U: CI | Br CI H30 CH3 CH3 H3C I \W'“? “7 1 2 3 4 L\.\ nu. ‘v-Lk A 1 > 4 > 3 > 2 *bhfflf‘m’“ B 4>1>2>3 2 > 3 > 4 > 1 D 3 > 4 > 1 > 2 11. The order of basicity for the following bases, from strongest to weakest, is: \Llflkfl ‘_\ {x a; (\g ' it: t CH35> CHsse (CH3)2Ne H30e m _ K ‘ L. it. ~ ' 5 L3 1 2 L 3 4 1, .- 3 ,3 .3, \ Wais‘b [rm-2" L {(1%)} 2e ' r1 _'; a p 3>4>1>2 /. , (g 4>3>1>2 L‘iipn 4-H;- 4 > 2 > 3 > 1 " l2. Which of the following statements is FALSE for an SNl mechanism? L _, j" A The reaction rate depends on the nucleophilicity of the attacking reagent. 1' rlL ‘I’ I ‘1: J may»: "T , L i 1' B The reaction intermediate is a carbocation. “\ih‘it r J; L; elf-l"- L“ C Tertiary alkyl halides react much faster than secondary alkyl halides. T ( L). .U Jojo»,- D Increasrng the polarity of the solvent by increasmg the H20 content speeds up the reaction. I ) T. 4 13. The stereochemieally pure alkyl halide shown is added to methanol (CHgOH). Possible (major and minor) rcaction products are: H3OE Q$01 i' 1 2 . A My _ \ X cf? B 1 and 2 only / kit-H a“ I (K;- m,-.i_ tlx E C 2 only ./’ all are possible H30; §OCH3H3COE $0M CH3 CH3 cagon <~ \ Ev, , .w OCH3 OCH; 3 4 l4. Predict the reaction types for the following reactions: H \Br w 1 m )‘V + —~ is?» Br CH3 I I (b) O + HZNCHg —> 591.. H H I A (a): 8N1; (b): sNi \_ I t_ w __ H K HEW. B (a): 8N2; (b): E2 l h b to at,» K C (a): E2; (b): E1 \pa :3“ (a): 8N2; (b): SN2 15‘ The fonowmg almth dEhydrate to give the corresponding alkenes in the presence of H2804. Rank their reactivities in the dehydration reactions (from highest to lowest), CHZOH OH t: ®”C§®C©‘ 4 . C cw" by t: c Ell—i if-x @}1>4>2>3 vie _ B 4 > 1 > 2 > 3 a mum; fl C 1 > 4 > 3.> 2 Lfflbl, l’x 7L _, D 3>2>l>4 16. What is the expected major product in the following reaction? <3 ‘l‘fiunfi bib- ‘3'“: NaOCH}, é >—B % >7 F: r CHBOH Na OCH3 Br A B Ir- ). C _ a 7 l,\ db. cL-{fl L” 5 l7. Which of the following statements is FALSE? A When 2-bromobutane is subjected to an E2 reaction, 3 possible alkenes may be formed. —_ ("f- SNl reactions of 2° halides usually occur with exclusive inversion of configuration. 1f- / FAQ: and C in an El reaction, if more than one al‘kene can be formed, the most stable alkene usually ‘5 “"‘M‘ predominates. D If (R)—2-bromobutane undergoes an 8N2 reaction with sodium thiophenoxide (NaSPh), the substitution product will have (S)-configuration. V. 18. A two—step reaction wherein substance A is converted to substance C is represented in the following energy profile. Which one of the following statements is TRUE? Energy I t [3) Reaction Coordinate _ .I Km x . . . . iv- e‘ {A ,1 The rate-determining step IS from B to C. 'T \I __ V kw HE. B The overall reaction is endothermic. "? — A in 1‘33) ""“"" ' _ " C There is only one transition state in the reaction from A to C. F I. f .3' “:5 D A is the most unstable spec1es 1n the react10n. 1-: f I b, 3 5‘ £3) UL )- 5 _r*_..,__-\., 19. Which set of the reagents can accomplish the following conversion? (You may or may not need several steps.) fix ea _‘ cis-2-pentene trans-Z-Pentene Br I. A Na, NH3 '— no ‘31 B Brz; then excess NaNHg, NH3 F4?» -/- “(if Brz; then excess NaNHZ, NH3; then Li, NH3 \. a. a' .: H - D Brz; then Li, NH3 mu. a t; it it, 20. For the following compounds, the order of decreasing Brensted acidity, from most acidic to least acidic, is: L, _::-u_. , I q I b F, A CH3CH20H > CF3CH20H > (CH3)3COH .4 (7 e: L— H 5" L. *3 <1 its uln- \g a '13 (CH3)3COH> CF3CH20H> CH3CH20H " 3 ' a I J I r I CF3CH20H > CH3CH20H > (CH3)3COH g {melt-,1: {gait l: C its L Hg LL-l-t (t, (CH3)3COH > CH3CH20H > CF3CH20H ' _ i5 _ ,_ j k (I I -— .. r >~w K -— like em I: Db ...
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2006Midterm2card001solutions - Chemistry 266 Midterm Test 2...

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