UNIVERSITY OF VICTORIA FINAL EXAMINATION, DECEMBER 2008 CHEMISTRY A01 PRACTICAL SPECTROSCOPY

Transcription

1 UNIVERSITY OF VICTORIA FINAL EXAMINATION, DECEMBER 2008 CEMISTRY A01 PRACTICAL SPECTROSCOPY TIME: 3 OURS INSTRUCTOR: Dr Reg Mitchell IN TIS EXAM TERE SOULD BE 26 WITE PAGES (check this) (which includes TIS COVER SEET) [NOTE: PAGES ARE PRINTED BOT SIDES] + A BLUE SIGNATURE SEET YOU ALSO SOULD AVE A GREEN COMPUTER SEET A YELLOW ANSWER SEET PACK (2 sheets, 4 sides) A PINK DATA SEET PACK (3 sheets, 6 sides) Report to the invigilator if any of these are missing now ANSWER QUESTIONS 1-60 [1.2 marks each] ON TE GREEN COMPUTER SEET WIT A PENCIL = 78 marks; ANSWERS TAT REQUIRE YOU TO DRAW A STRUCTURE, GIVE A FORMULA, ETC, AVE LETTERS AS QUESTION # S. ANSWER TESE ON TE YELLOW SEETS PROVIDED. USE A PEN OR PENCIL, BUT MAKE SURE YOUR ANSWER IS READABLE = 82 marks. Total Marks = 160; Total minutes = 180! MAKE SURE YOUR NAME (LAST(FAMILY) ; NAME FIRST) AND REGISTRATION NUMBER V enter only the last 7 digits ARE ON BOT TE GREEN COMPUTER SEET AND TE YELLOW ANSWER SEETS - DO TIS NOW, AND ALSO SIGN TE BLUE SEET PLACE YOUR STUDENT ID ON TE TOP RIGT CORNER OF TE TABLE ELECTRONIC CALCULATORS ARE PERMITTED, BUT MUST NOT CONTAIN STORED PROGRAMS OR FORMULAE

2 CEM Final Exam Page 2 NUMBERED QUESTIONS: ANSWER ON TE GREEN COMPUTER SEET PROVIDED USING A PENCIL; COICES MAY BE USED MORE TAN ONCE. SOME QUESTIONS MAY REQUIRE DATA SUPPLIED ON TE PINK SEETS! Four IR spectra (Q1-4) and ten compounds (a - j) are shown below. Assign each spectrum to a compound 's cm -1 Q1 Q2 Q3 Q 's cm -1

3 CEM Final Exam Page 3 Compounds a - j for Q 1-4 C 2 C 2 O C 2 COO C 2 CO COC 3 C C (a) (b) (c) (d) (e) CO COO C 3 C2 O NC 3 C N C 3 (f) (g) (h) (i) (j) Compound A is aromatic and contains normal functional groups, and shows the following ir spectrum Scale cm -1 In its mass spectrum, A showed an M + at 154 and an M+2 peak at 156 in a 3:1 ratio. As well an 9% (M+1) peak at 155 was seen. igh resolution MS indicated only one oxygen atom to be present in a molecule of A. Strong fragment peaks were seen at m/z 119 and ow many carbon atoms are present in a molecule of A (a) 3 (b) 4 (c) 5 (d) 6 (e) 7 (f) 8 (g) 9 (h) 10 (i) 11 (j) 12 Determine the molecular formula for A and write it on the yellow answer sheet [3 marks] Determine the structure of A and draw it on the yellow answer sheet -show all s [5 marks]

4 CEM Final Exam Page 4 O O O Cl cyproterone The structure of cyproterone, which is an anti-androgen used in the birth control pill Diane-35, is shown above. Using the wavelength choices (nm) (a) (b) (c) (d) (e) (f) and ε choices (a) 15,000 (b) 1,000 (c) 200 (d) 40 (e) 1 6 Where would you expect to find π 3 6 π 3 * for the diene-one chromophore 7 What ε value would this (Q#6) absorption have 8 Where would you expect to find n 6 π 3 * for diene-one chromophore 9 What ε value would this (Q#8) absorption have 10 Where would you expect to find n 6 π* for the methylketone chromophore. 11 Where would you expect to find π 6 π* for the methylketone chromophore Using the choices (a) hypsochromic shift (b) hyperchromic shift (c) bathochromic shift (d) hypochromic shift (e) no shift 12 ow would you expect the wavelength of the absorption for a simple dienone to compare to the chloro-dienone in cyproterone

5 CEM Final Exam Page 5 Mercury (group 12/IIb) forms mercuric iodide which is intense scarlet red, but the chloride (mercuric chloride) is white 13 At what wavelength (nm) does gi 2 absorb light: (a) 670 (b) 600 (c) 550 (d) 500 (e) 450 (f) 400 (g) 350 (h) 300 (i) 250 (j) then using the transition choices: (a) π 6 π* (b) π 6 σ* (c) π 6 n* (d) n 6 π* (e) L 6 M CT (f) M 6 L CT (g) d 6 d (h) π 6d (i) d 6 π* (j) π 1 6 d* and ε choices: (a) 4000 (b) 300 (c) What transition causes the red color of gi 2 15 What would its ε value be On the other hand for the copper (group 11/Ib) compounds, both copper (II) iodide and chloride are pale blue 16 What transition would CuCl 2 show (choices above) 17 and what would its ε value be (choices above) 18 and at what wavelength would its absorption be (choices below) (a) 670 (b) 600 (c) 550 (d) 500 (e) 450 (f) 400 (g) 350 (h) 300 (i) 250 (j) Mercuric sulfide as vermillion is also bright red, but when prepared from mercuric chloride and 2 S, it is black - what wavelength of light does black mercuric sulfide absorb (a) 670 (b) 600 (c) 550 (d) 500 (e) 450 (f) 400 (g) 350 (h) 300 (i) 250 (j)

6 CEM Final Exam Page 6 Compound B is often used to detox heavy metals like mercury. It shows an M + at m/z 108 and also peaks at 109 and 110 in a 100:3.3:8.8 ratio, and as well a small peak at 112 (~0.2%). Strong fragment peaks were seen at m/z 107, 106, 75, 74 and 42. [Isotopic data is available on the pink sheets] The 1 NMR spectrum (low temperature) of compound B is shown below: Integration ratios 2 : 1 : 1 Multiplicities q 5 t The peak (triplet) at δ 1.3 exchanges with D 2 O on warming or in the presence of NaOD (base), and becomes a singlet, and then the peak at δ 2.6 becomes a triplet. Determine the structure of compound B and write in the space provided on the yellow answer sheet. [7 marks]

7 CEM Final Exam Page 7 A product C was obtained from a reaction. The NOESY and COSY spectra of the product, compound C, are shown on the next pages. Chemical shifts are approximate. Make use of obvious chemical shifts and NOESY s to decide which of the following 14 isomers of C are possibilities, and confirm your choice with COSY s, and then enter the number of the structure you have chosen on the yellow answer sheet [8 marks] Answer choices: C 3 CO CO C 3 CO CO C 3 C C 3 CO CO C 3 CO CO 2 6 C C 3 CO CO C 3 CO C 3 CO C C CO CO C 3 4 C 3 11

8 CEM Final Exam Page 8 NOESY SPECTRUM OF C (approx chem shifts given) (note COSY correlations have been removed, and each peak is shown as a line) Chemical shift, multiplicity (m) and integral (I) are shown for each peak

9 CEM Final Exam Page 9 COSY SPECTRUM OF C Do not forget to put your answer on the yellow sheet!

10 CEM Final Exam Page 10 For the compound b CO C 3 C 3 a c O Use these choices of chemical shift and the pink data sheets (a) 7.66 (b) 7.55 (c) 7.44 (d) 7.33 (e) 7.22 (f) 7.11 (g) 6.80 (h) 6.70 (i) 6.49 (j) Calculate the chemical shift for a 21 Calculate the chemical shift for b 22 Calculate the chemical shift for c using the choices: (a) ABC (b) AMX (c) A 2 X (d) AA X (e)abx (f) AA B 23 What will be the spin system for the protons a, b and c at 360 Mz 24 In a monosubstituted benzene, which group produces the largest difference in chemical shift between the ipso and ortho carbons. (a) C 3 (b) CO (c) O (d) COO (e) F (f) I (g) OC 3 (h) NO 2 (i) N 2 (j) C(C 3 ) 3 25 What colored Christmas lights would emit photons of energy 198 kj/mole (a) red (b) blue (c) green (d) yellow (e) orange (f) violet (g) white

11 CEM Final Exam Page 11 For the molecule 3 N, the N stretch appears at 3400 cm At what wave number (cm -1 ) would you expect to find the N-T stretch [ 3 = Tritium, which has mass =3] (a) 2404 (b) 2090 (c) 1867 (d) 1700 (e) 1133 (f) 5532 (g) 4810 (h) 3500 (i) 3300 (j) 2560 Using: (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 (i) 12 (j) ow many ir active stretches would you expect to see in 2 NT 28 ow many fundamental vibrations are possible and using (cm -1 ) : (a) 3300 (b) 2200 (c) 1700 (d) 1300 (e) 800 (f) When 3 N is oxidized, N 2 is formed; at which fundamental frequency would the nitrogen-nitrogen stretch be Carbon disulfide, CS 2 shows 3 fundamental frequencies (bands), which are at 1510, 657 and 397 cm -1 Using (a) none (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) linear (i) bent 30 Based on electron count, is CS 2 linear or bent? 31 Then, how many fundamental bands would you expect 32 ow many active ir bands would you see Using (a) P (b) Q (c) R (d) P, Q (e) P, R (f) Q, R (g) P, Q, R 33 Which branches should the 1510 cm -1 band show 34 Which branches should the 397 cm -1 band show

12 CEM Final Exam Page 12 The 1510 cm -1 fundamental frequency for CS 2 also shows a band at 1490 cm -1, corresponding to a transition from v=0;j=4 to v=1;j=3 35 Would the 1490 cm -1 line appear in the (a) P branch (b) Q branch (c) R branch (d) P and R branches (e) all branches (f) none of the branches 36 What is the rotational constant B (in cm -1 ) (a) 2.0 (b) 1.67 (c) 1.43 (d) 1.25 (e) 1.0 (f) 20.0 (g) 10.0 (h) 5.0 (i) 3.33 (j) Where would the first hotline be found (cm -1 ) (a) 1520 (b) 1510 (c) 1500 (d) 3040 (e) 3020 (f) 3000 (g) 760 (h) 755 (i) 750 (j) In a real molecule, as you increase energy, does the spacing of the lines in the rotational spectrum get (a) closer together (b) further apart (c) remain the same 39 ow will the 13 C NMR spectrum of C 3 OD appear at low temperature (no decoupling) (a) 1:2:1 triplet of 1:3:3:1 quartets (b) 1:1:1 triplet of 1:3:3:1 quartets (c) 1:3:1 triplet of 1:3:3:1 quartets (d) 1:1 doublet of 1:3:3:1 quartets (e) 1:1:1:1:1 pentet (f) 1:1:1 triplet of 1:2:2:1 quartets (g) 1:1:1:1 quartet of 1:1:1 triplets (h) 1:1:1:1 quartet of 1:2:1 triplets (i) 1:3:3:1 quartet of 1:2:1 triplets (j) 1:3:3:1 quartet of 1:1:1 triplets 40 At UVIC, we use the 360Mz proton magnet to observe 2 D spectra. What frequency (Mz) will the probe operate at to observe 2 D (pink data sheet) (a) 90 (b) 53.3 (c) 2430 (d) 1440 (e) 14.4 (f) 1080 (g) 11 (h) 338 (i) 27 (j) 4

13 CEM Final Exam Page 13 For the molecule D: P Cl Pt F P 3 Assume 1 J Pt,F = 600 z, 1 J Pt,P = 300 z, 2 J Pt, = 100 z, 1 J P, = 200 z, trans- 2 J P,F = 80 z, cis- 2 J P,F = 50 z, and that the benzene ring protons do not couple to P, Pt, F. Assume normal other couplings and that for 3 J couplings, -F > -P. using: (a) dtq (b) dddq (c) tdq (d) dt (e) ddq (f) qdd (g) dqdd (h) dqt (i) tq (j) qt 41 ow will the 195 Pt spectrum appear 42 ow will the 19 F spectrum appear for a molecule that does not contain 195 Pt 43 ow will the 19 F spectrum appear for a molecule that only contains 195 Pt 44 ow will the 31 P spectrum of the P 3 appear for a molecule that does not contain 195 Pt ow will the P spectrum of the P 3 appear for a molecule that only contains 195 Pt 46 What will be the width (z) of the 195 Pt spectrum (Q41)(i.e. distance in z between far left hand and far right hand lines) (a) 150 (b) 450 (c) 600 (d) 750 (e) 900 (f) 1050 (g) 1200 (h) 1350 (i) 1500 (j) What is the spin system for this compound with a NON spin active Pt (ignore benzene protons) (a) ABCD (b) ABB D 3 (c) ABMX 3 (d) ABCD 3 (e) ABMXX X (f) AMM X 3 (g) AMX (h) A 2 MX (i) AMM XX X (j) ABB X 3

14 CEM Final Exam Page For the compound FC 2 -PtCl 3, if 2 J Pt, = 100 z, 2 J Pt,F =150z and 2 J,F = 50 z, and if the platinum spectrum shows the most shielded line is 2047 z downfield from the reference signal, what is the chemical shift of this Pt. The spectrum was run on a 500 Mz proton spectrometer (pink pages) (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) For the hydrogen signal of the compound referred to in Q48, what would be the intensities of the lines in the real hydrogen spectrum of a sample that contains natural abundance platinum- write your answer using the format 1:1:2:1 etc on the yellow answer sheet [3 marks] int: you might want first to draw to scale the positions of the lines of the spectrum, space below

15 CEM Final Exam Page 15 TE OBJECTIVE IN TE FOLLOWING QUESTIONS IS TO SOLVE TE STRUCTURES. TERE ARE SOME QUESTIONS TO ANSWER ON TE GREEN COMPUTER SEETS; YOU WILL DRAW YOUR SOLUTION TO EAC STRUCTURE ON TE YELLOW SEETS. WORK SPACE IS PROVIDED AFTER EAC QUESTION, TIS WILL NOT BE MARKED; ONLY GIVE YOUR FINAL ANSWER ON TE YELLOW SEETS, giving more than one answer leads to penalties. ALL Proton spectra are 300 Mz COMPOUND E, C 7 12 O 2 49 ow many DBE has compound E (a) 0 (b) 0.5 (c) 1 (d) 1.5 (e) 2 (f) 2.5 (g) 3 (h) 3.5 (i) 4 (j) 4.5 The IR spectrum: 1735 cm What functional group is present in compound E (a) alcohol (b) aldehyde (c) acid (d) alcohol-ketone (e) ether (f) ester (g) alcohol-aldehyde (h) ketone (i) ether-aldehyde (j) anhydride 13 C NMR: 171s 139s 119d 62t 26q 21q 19q

16 CEM Final Exam Page 16 1 NMR Spectrum The peak at δ 5.3 is a triplet (split again by small couplings), and at δ 4.6 is a doublet. 51 ow many chemically different hydrogens are there (a) 1 (b) 2 (c) 3 (d) 4 (e) 5 (f) 6 (g) 7 (h) 8 (i) 10 (j) 12 Write your proton integration values on the yellow answer sheet in the place provided in the form a:b:c:etc [2 marks] Draw your structure for compound E on the yellow answer sheet in the place provided [7 marks]

17 CEM Final Exam Page 17 Compound F gave a low resolution mass spectrum M + at m/z 222. A high resolution mass spectrum on the CON containing fragment of the molecule gave m/z = (±0.004) and as well, compound F contains four atoms of another element E with spin = 1/2. Formula m/z C N O C N O m/z Determine the molecular formula for compound F and enter it on the yellow answer sheet in the space provided. [4 marks] 52 ow many DBE are in compound F (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 5.5 (h) 6 (i) 6.5 (j) 7 The infra red spectrum of F is shown below:

18 CEM Final Exam Page Which functional group is present in F (a) alcohol (b) aldehyde (c) ketone (d) acid (e) ester (f) acetylene (g) alcohol-aldehyde (h) alcohol-ketone (i) aldehyde-ketone (j) acid chloride The 13 C NMR and DEPT135 data are given below: [* only 1 J shown] 13 C{ 1 } t* 108t* DEPT +ve a a +ve +ve +ve +ve a +ve [a=absent] When both 1 and element E were decoupled, the peaks at 117 and 108 were singlets Using (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 54 ow many protons are on the carbon at δ ow many protons are on the carbon at δ ow many element E s are on the carbon at δ NMR Spectrum [300Mz] Integrations 1: (impurity) 1:1:1:1 : 1 main multiplicity (note some small long range coupling also is present): s d s t d tt

19 CEM Final Exam Page 19 Draw your structure for compound F on the yellow answer sheet in the place provided [8 marks] work space:

20 CEM Final Exam Page 20 Compound G: C O 2 57 ow many DBE in G (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 The IR Spectrum showed a strong broad peak at 3400 cm -1 and a peak at 970 cm -1 1 NMR Spectrum [300Mz]: Integrations: 1 : 1:1:1:1:1 : 2 : 3 : 3 Multiplicities s s, d, d, d, dq q d t The peak at δ 8.5 exchanges with D 2 O 13 C NMR 147(s) 146(s) 131(s) 130(d) 123(d) 117(d) 113(d) 112(d) 64(t) 18(q) 14(q) From this data, you should be able to solve the general structure for G, but not which isomer. At low temperature, the peak at δ 8.5 shows an MQC (J=10) correlation to the carbon at δ 113 (that is attached to the proton that is a singlet at δ 6.8) and to the carbon at δ 146. The proton at δ 4.0 also only shows a correlation to this carbon at δ 146. You should now be able to decide the structure of G, but see next page

21 CEM Final Exam Page 21 You could (time permitting) confirm your choice with the information that the proton (widely spaced doublet) at δ 6.2 correlates to the carbons at δ 113, 117 and 18, and the fact that the proton (doublet) at δ 6.6 correlates with the carbons at δ 147 and 131. Draw your structure for compound G on the yellow answer sheet in the place provided [13 marks] work space

22 CEM Final Exam Page 22 COMPOUND, C 6 16 N 2 58 ow many DBE are present in compound (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 (i) 8 (j) 9 The IR spectrum : 3400, 3300, 3200 cm -1 The 1 NMR spectrum [300Mz]: Integrations: 2:2:2 :2:2 : 3:3 Multiplicities t t t 5 6 s t The 3 peak at δ 1.1 is exchanging and also exchanges with D 2 O

23 CEM Final Exam Page 23 The 13 C NMR spectrum: 52(t) 48(t) 41(t) 34(t) 23(t) 14(q) Draw your structure for compound on the yellow answer sheet in the place provided [10 marks] work space

24 CEM Final Exam Page 24 COMPOUND I, C 8 6 ClN 59 ow many DBE are in compound I (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 (i) 8 (j)9 The IR spectrum of compound I: 2220 cm What is the main functional group present in compound I (a) 1 o amine (b) 2 o amine (c) 3 o amine (d) terminal alkyne (e) non-terminal alkyne (f) nitrile (g) acid chloride (h) amide The 13 C NMR spectrum of I: 142(s) 135(s) 132(d) 131(d) 130(d) 118(s) 111(s) 20(q) The proton spectrum of I is on the next page:

25 CEM Final Exam Page 25 The proton spectrum of I: MQC (J=135) Short range hetcor Proton spectrum Carbon Spectrum

26 CEM Final Exam Page 26 MQC (J=10) [Long range etcor] Proton spectrum Carbon spectrum Draw the structure of compound I on the yellow answer sheet [12 marks] work space -END-

27 FINAL EXAMINATION, DECEMBER 2008 YELLOW ANSWER SEETS CEMISTRY A01 PRACTICAL SPECTROSCOPY LAST NAME: FIRST NAME AND INITIAL: REGISTRATION NUMBER: V0-0 ALSO PUT YOUR NAME ON SEET TWO (Side 3). GIVE ONLY YOUR FINAL STRUCTURES ON TIS SEET, SPACE FOR ROUG WORK IS PROVIDED ON TE QUESTION SEET. Part marks will be given for partial structures or partly correct structures; do NOT give ANY of the detail as to how you derived the structure. TESE PAGES ARE PRINTED BOT SIDES! MAKE SURE YOU SOW ALL ATOMS INCLUDING YDROGENS IN YOUR FINAL STRUCTURES MARKS FROM TIS SEET [/82] = {Page 3} FORMULA FOR COMPOUND A [3 MARKS] = {Page 3} STRUCTURE FOR COMPOUND A [ 5 MARKS]

28 Yellow Answer Sheet 1, page Final 2008 {Page 6} STRUCTURE FOR COMPOUND B [7 marks] = {Page 7} STRUCTURE FOR COMPOUND C [8 marks] = [a number from 1-12 is required] {Page 14} Relative intensities of the hydrogen lines for compound of question 48 [3 marks] [format required = 1:b:c: etc] = {Page 16} COMPOUND E: Proton Integration values [a:b:c: etc][2 marks]= {Page 16} STRUCTURE FOR COMPOUND E (show all s) [7 marks]

29 Yellow Answer Sheet 2, page Final 2008 LAST NAME FIRST NAME {Page 17} MOLECULAR FORMULA FOR COMPOUND F [4 marks] {Page 19} STRUCTURE FOR COMPOUND F (show all s) [8 marks] {Page 21} STRUCTURE FOR COMPOUND G (show all s) [13 marks]

30 Yellow Answer Sheet 2, page Final 2008 {Page 23} Structure FOR COMPOUND (show all s) [10 marks] {Page 26} STRUCTURE FOR COMPOUND I (show all s) [12 marks]