THE UNIVERSITY OF CALGARY FACULTY OF SCIENCE FINAL EXAMINATION CHEMISTRY 353

Transcription

1 TE UIVERSITY F ALGARY FAULTY F SIEE FIAL EXAMIATI EMISTRY 353 April 20th, 2006 Time: 3 ours PLEASE WRITE YUR AME, STUDET I.D. UMBER TE MPUTER ASWER SEET AD TE BKLET FR TE WRITTE ASWER QUESTIS. READ TE ISTRUTIS AREFULLY The examination consists of Parts 1-10, each of which should be attempted. ote that some Parts provide you with a choice of questions, e.g. answer 5 out of 6. These will be graded in order the answers appear until the required number have been completed, regardless of whether they are right or wrong. Parts 1-7 will be computer graded, and only Parts 8, 9 and 10 are to be answered in the booklet. Parts 1-7 consist of a series of multiple choice questions numbered 1-58 which are to be answered on your computer answer sheet. Indicate your answer by blackening out the appropriate space, A, B,, D or E on the answer sheet. Use a pencil only and not ink. In some cases it is required that you indicate multiple items for a complete and/or correct answer by blackening out more than one space. In some other cases more than five options are available and some of these also require more than one space to be blackened out. For an example, an option specified as AB requires that you blacken out both space A and space B. Part marks may be awarded in some of the questions. Incorrect answers must be erased cleanly. A periodic table with atomic numbers and atomic weights and tables of spectroscopic data are provided at the end of the examination paper. Molecular models are permitted during the exam; calculators are also permitted, but T programmable calculators. Absolutely no other electronic devices are allowed.

2 hem 353 ont'd Page 2 of 19 12% PART 1: RELATIVE PRPERTIES ASWER AY EIGT (8) F QUESTIS Arrange the items in questions 1-10 in DEREASIG RDER (i.e. greatest, most etc. first) with respect to the indicated property. Use the following code to indicate your answers: A i > ii > iii D ii > iii > i B i > iii > ii E iii > i > ii ii > i > iii AB iii > ii > i 1. The relative reactivity towards lithium aluminum hydride in tetrahydrofuran (TF) of each of the following: 3 3 i ii iii 2. The relative reactivity towards ( 3 ) 3 l / All 3 of each of the following: i ii iii 3. The relative acidity of the most acidic hydrogen in each of the following: i ii iii 4. The relative oxidation state of the atom in each of the following: i ii iii 5. The relative reactivity towards (dark, 2 ) of each of the following : 2 i ii iii TIUED -->

3 hem 353 ont'd Page 3 of 19 Use the following code to indicate your answers: A i > ii > iii D ii > iii > i B i > iii > ii E iii > i > ii ii > i > iii AB iii > ii > i 6. The relative acidity of the most acidic hydrogen in each of the following: + i + ii iii 7. The relative yields of the following products from the reaction of (1) B 3 then (2) aq. a / 2 2 with 1-methylcyclohexene : i ii iii 8. The resonance energies of each of the following: i ii iii 9. The relative reactivity of the following towards benzaldehyde in dry TF: 3 Mg 3 Li 3 i ii iii 10. The relative basicity of the following carbanions : 3 _ i ii iii TIUED -->

4 hem 353 ont'd Page 4 of 19 9% PART 2: LABRATRY ASWER AY SIX (6) F TE QUESTIS The questions 11-13, refer to the answers below: A Water B 5% a 3 (aq.) 5% a (aq.) D 5% l (aq.) E one of the above 11. Select all solvents that would completely dissolve acetophenone. 12. Select all solvents that would completely dissolve aniline. 13. Select all solvents that would completely dissolve phenol. The questions 14-18, refer to the following functional groups: A Alcohol AB Amine B Aldehyde A arboxylic Acid Alkane AD Ester D Alkene AE Ketone E Amide B Phenol 14. A functional group that gives a positive result with Tollen s test. 15. A functional group that gives a positive iodoform test. 16. A functional group that gives a positive ferric chloride test. 17. A functional group that would react with phenyl isocyanate to yield a phenyl urethane. 18. A functional group that would readily react with hydroxylamine to yield an oxime. TIUED -->

5 hem 353 ont'd Page 5 of % PART 3: STRUTURE AD PRPERTIES ASWER AY TE (10) F TE QUESTIS In some cases more than one answer may be correct and all compounds that apply must be selected for full credit. SET 1: ( 3 ) 3 ( 3 ) 3 ( 3 ) 3 ( 3 ) 3 ( 3 ) 3 A B D E Answer questions by selecting the compounds from SET 1 above. 19. Which compound (in its most stable conformation) would react the fastest with K t Bu 20. Select two compounds that represent a pair of enantiomers 21. Select two compounds that are conformational isomers 22. Select a compound with an (S,S) configuration SET 2: A B D E Answer questions by selecting the compounds from SET 2 above. 23. Which compound most readily forms an acetal when reacted with ethylene glycol in the presence of a catalytic amount of an acid 24. Which compound(s) has (have) enolisable hydrogens 25. Which compound is not readily reduced by LiAl Which compound would react with a Schiffs reagent to give a magenta colour TIUED -->

6 hem 353 ont'd Page 6 of 19 SET 3 S B A B D E Answer questions by selecting the compounds from SET 3 above. 27. Which structure(s) is (are) aromatic as drawn 28. Which aromatic structure(s) has (have) an aromatic conjugate acid 29. Which structure(s) is (are) non-aromatic as drawn, but has (have) an important aromatic resonance structure TIUED -->

7 hem 353 ont'd Page 7 of 19 9% PART 4: PRDUTS F SYTESIS ASWER AY SIX (6) F QUESTIS For each of the questions identify the major product obtained from each of the reaction sequences shown by selecting from the list of possible products provided Fe 3, 2 2. Sn, l 3. K A B D E ( 2 ) 2 -, + 2. Excess Mg, then , 2 A B D E LiAl 4, then a, I A B D E TIUED -->

8 hem 353 ont'd Page 8 of a, A B D E ab 4, 2. Tsl, Pyridine 3. a A Ts B D E Mg, Ether 2. Et 3. atalytic +, 2 Et Et A B D E Sl thylaniline 3. LiAl 4 then A B D E 3 TIUED -->

9 hem 353 ont'd Page 9 of 19 9% PART 5: STARTIG MATERIALS FR SYTESIS ASWER AY SIX (6) F QUESTIS For each of the questions 37-43, choose the starting material from the selection provided that gives the product indicated via the transformations shown then Zn in ab 4 3. Excess P 3 4. Excess K 5. +, 2, eat A B D E yclopentadiene, eat 2. s 4 then 3. I Et Et 3 A B D 3 3 E , atalytic + 2. Mg, TF then 2 = then , heat 3 3 A B D E 3 TIUED -->

10 hem 353 ont'd Page 10 of A atalytic + eat B D E Ph 3 P then n-buli 2. yclohexanone 3. 2 I 2, Zn-u 2 3 A B D E 42. Mg-( 2 ) 4 -Mg then 3 + Et A B D E (50:50 of these enantiomers) A B D E TIUED -->

11 hem 353 ont'd Page 11 of 19 9% PART 6: REAGETS FR SYTESIS ASWER ALL F TE QUESTIS The following synthesis shows a possible synthesis of Gleevec, which is a drug produced by ovartis and used for cancer treatment. From the list of reagents provided in the table below, select the best reagent combination to carry out each of the reactions required at each numbered step % yield A B 2 A + B a, i-pr l 52 A. 3 / 2 S 4, heat B. aet / Et. 3 a / 3 D. ( 3 ) 2. toluene, then 3 2 E. Fe / l AB. 1. Sn / l 2. a A. conc. 2 S 4 AD. B 3 then aq. a / 2 2 AE. 2 / 2, heat B. pyridine, room temperature BD. excess 3 MgI then 3 + BE. formaldehyde, (), heat. D. S or l 2 E. LiAl 4 then 3 + DE. ab 4 AB. Ph 3 P= 2 ABD. LDA, Li(i-Pr) 2 ABE. P, 2 l 2 BD. 2 / gs 4 / 2 S 4 TIUED -->

12 hem 353 ont'd Page 12 of 19 9% PART 7: EXPLAATI F PEMEA ASWER ALL F TE QUESTIS SE TE SIGLE EXPLAATI TAT BEST RATIALISES TE PEME IDIATED. 53. The 1 -MR spectrum of,-dimethyl acetamide (DMA, the methyl groups attached to the nitrogen. This is because: ) shows two peaks for A The atom has a lone pair and is more electronegative than. B The lone pairs on and participate in ydrogen bonding. The bond between and the carbonyl has some double bond character. D There is a tautomeric form of DMA where the methyl groups are not equivalent. E The is sp 3 hybridized. 54. Which side of the following equilibrium is favoured and why + 2 A The aldehyde because = bond is stronger than - bond. B The aldehyde because formaldehyde is not soluble in 2. The hydrate because there is generally less steric hindrance in an sp 3 hybrid. D The hydrate because it is the entropically favoured product. E The hydrate because the formaldehyde carbon is electrophilic. 55. In the following unsuccessful imine reaction, why does the reaction not go to completion p no imine formed. A B D E At p 10, the ketone will be protonated and the amine cannot attack the carbonyl. At p 10, the ketone will form the enolate ion. At p 10, the tetrahedral intermediate is protonated and 2 leaves. At p 10, the amine is ionic and the tetrahedral intermediate is deprotonated. At p 10, the amine will be neutral and the tetrahedral intermediate cannot lose For the rate of the saponification of the following lactones: TIUED -->

13 hem 353 ont'd Page 13 of 19 I II A. I reacts the fastest because the carbonyl is less stabilized B. I reacts the fastest because the tetrahedral reaction intermediate is more stable due to staggered bonds. II reacts the fastest because the five membered ring has more strain D. II reacts the fastest tetrahedral reaction intermediate is more stable due to eclipsed bonds E. Both I and II do not react under these reaction conditions due to the enhanced stability of a cyclic ester 57. For the following reaction: Ph Ph K Ph + eat Ph III Ph IV Ph A. An approximately 50:50 mixture of III and IV are obtained under these conditions B. A greater amount of III would be produced because it is formed the fastest (the kinetic product). A greater amount of III would be produced because it is more stable (the thermodynamic product) D. A greater amount of IV would be produced because it is formed the fastest (the kinetic product) E. The reaction would not proceed because K is not a strong enough base 58. When added to water, hexachloroacetone A. Forms a biphasic mixture with water as the lower layer B. Forms a biphasic mixture with water as the upper layer. Is rapidly hydrolysed to form two equivalents of acetic acid and l D. Rapidly forms a hydrate E. Rapidly forms an enol TIUED -->

14 hem 353 ont'd Page 14 of 19 10% PART 8: MEAISM ASWER TW(2) QUESTIS, E FRM PART A AD E FRM PART B. WRITE YUR ASWERS I TE BKLET PRVIDED. REAGETS TER TA TSE ALREADY SW ARE REQUIRED FR TESE QUESTIS. (4) PART A: Use a curly arrow mechanism to explain E of the following transformations : i ii S 4 iii Excess Mg then (6) PART B : Use a curly arrow mechanism to answer E of the following : i. Provide a detailed mechanism showing all the steps for the following: Et 2 Et K 2 3 Et ii. Provide a detailed mechanism showing all the steps for the following: 2 atalytic + TIUED -->

15 hem 353 ont'd Page 15 of 19 12% PART 9: TTAL SYTESIS WRITE YUR ASWERS I TE BKLET PRVIDED Design an efficient synthesis for any TREE (3) of the following target molecules using any of the starting materials and reagents given in the accompanying list. Show the product of each step and clearly identify the required reagents. D T SW MEAISMS F Permitted Starting Materials and Reagents* - Any inorganic materials - Any organic compounds with no more than FUR carbons - triphenyl phosphine - MPBA - Either of the following: * any materials that contribute carbon atoms to the target must come from this allowed list. TIUED -->

16 hem 353 ont'd Page 16 of 19 10% PART 10: STRUTURE DETERMIATI WRITE YUR ASWERS I TE BKLET PRVIDED ompound A was found to be 88.16% and 11.84% (from standard elemental analysis for ) and had a strong IR absorption at about 1600cm -1 and 13 nmr spectra peaks at 18, 114, 117, 140 and 142ppm. When A was heated in a sealed tube with ethene at 200 o it gave compound B which reacted rapidly with 2 / l 3 to give a colourless solution. When B was reacted with B 3 and then 2 2 / aq. a, compound was formed, IR absorption near 3000cm -1 (broad). When was reacted with acidic K 2 r 2 7 or P / 2 l 2 compound D, 7 12 was produced. The 13 nmr spectra of D had 7 peaks, one at 213ppm and the rest were below 50ppm. The IR spectra of D had a strong absorption at 1712cm -1. Reaction of D with 3 3 gave compound E, whose 13 nmr spectra also had 7 peaks : 175, 70ppm and the rest below 50ppm. Reaction of E with LiAl 4 / TF followed by a normal work-up gave racemic heptan-1,6- diol. When B was reacted with 3 followed with a 2 2 work-up it gave compound F, The IR spectra of F had strong absorptions near 3000 (broad) and 1710cm -1. Subsequent reaction of F with ab 4 / aq. Et followed by a normal work-up gave E again whereas reaction of F with LiAl 4 / TF followed by a normal work-up gave racemic heptan-1,6-diol. When B was reacted with 3 followed with Zn / acid work-up it gave compound G, The IR spectra of G had a strong absorption at 1725cm -1. Subsequent reaction of G with hot a / Et gave 1-cyclopent-1-en-1-ylethanone. ompounds, D and E were formed as a pair of enantiomers. Identify the compounds A, B,, D, E, F and G (structures are sufficient) IR / A / TS W2006 TE ED

17 hem 353 ont'd Page 17 of 19 Schematic diagrams of MR chemical shift data for and 13 MR 1 MR ppm 2 -Ar 3 2 -X 2-2 -S 2 R 2 R Ar- =- 2-2 = 2 = 0 13 MR = - = X Ar ppm 0

18 hem 353 ont'd Page 18 of 19 A orrelation Table of Infra-Red Group Absorption Frequencies TYPE F VIBRATI FREQUEY (cm -1 ) WAVELEGT (µ) ITESITY - Alkanes (stretch) s - 3 (bend) 1450 and and 7.27 m - 2 -(bend) m Alkenes (stretch) m (bend) s Aromatics (stretch) s (out-of-plane bend) s Alkyne (stretch) ca ca.3.03 s Aldehyde w w - Alkane not interpretatively useful = Alkene m-w Aromatic m-w Alkyne m-w = Aldehyde s Ketone s arboxylic acid s Ester s Amide s Anhydride ca ca s ca ca s - - Alcohols, Ethers, Esters, arboxylic acids s Alcohols, Phenols Free m -Bonded m arboxylic acids* m - Primary and secondary amines ca ca m itriles m = itro (R- 2 ) s s -X Fluoride s hloride s omide, Iodide <600 >16.7 s (* note that the - absorption of carboxylic acids which are solids and run as a nujol mull can be difficult to see as they maybe very broad)

19 hem 353 ont'd Page 19 of 19 PERIDI TABLE 1 1A 18 8A A 13 3A 14 4A 15 5A 16 6A 17 7A 2 e Li Be B F e a Mg Al Si P S l Ar K a Sc Ti V r Mn Fe o i u Zn Ga Ge As Se Kr Rb Sr Y Zr b Mo Tc (98) 44 Ru Rh Pd Ag d In Sn Sb Te I Xe s Ba * La f Ta W Re s Ir Pt Au g Tl Pb Bi Po (209) 85 At (210) 86 Rn (222) 87 Fr (223) 88 Ra ** Ac (227) 104 Rf (261) 105 a (262) 106 Sg (263) 107 s (262) 108 s (265) 109 Mt (266) 110 Uun (269) 111 Uuu (272) Lanthanides * 58 e Pr d Pm (145) 62 Sm Eu Gd Tb Dy o Er Tm Yb Lu Actinides ** 90 Th Pa U p Pu (244) 95 Am (243) 96 m (247) 97 Bk (247) 98 f (251) 99 Es (252) 100 Fm (257) 101 Md (258) 102 o (259) 103 Lr (260)