CHEM 213 FALL 2016 MIDTERM EXAM 2 - VERSION A

Transcription

1 CHEM 213 FALL 2016 MIDTERM EXAM 2 - VERSIN A Answer multiple choice questions on the green computer sheet provided with a PENCIL. Be sure to encode both your NAME and Registration Number (V#). You will draw the structures of Molecules AA-AB on the Separate Double-Sided STRUCTURE ANSWER SHEET. You will also enter your selection for Molecule T (bonus question) on that sheet. Be sure to put your NAME on that sheet as well. There should be 8 pages (double-sided) in this examination AND you should have a green Scantron form, PLUS a STRUCTURE ANSWER SHEET (double-sided). There are 14 graded multiple choice questions worth 21 marks and two structure solutions worth 24 marks for a TTAL of 45 MARKS. There is also a BNUS QUESTIN (molecule T) on the last page worth 5 extra marks. There are 50 minutes available for this examination so ration your time accordingly. YU MAY NLY USE A Non-Programmable CALCULATR. Substituent constants for 13 C and 1 H chemical shift prediction: δ aromatic C = Δ ipso + Δ ortho + Δ meta + Δ para δ arom H = Δ ortho + Δ meta + Δ para R Δ ipso Δ ortho Δ meta Δ para Δ ortho Δ meta Δ para H F NHCCH CH=CH N(CH 3 ) CH 2 CH

2 CHEM 213 Midterm 2 Version A November 22, 2016 Page 2 of 8 1. This is exam VERSIN A, mark A on the computer sheet as the answer to question 1 Consider Molecule R when answering Questions 2-8; hydrogens are numbered and carbons are lettered. 2. How many unique 13 C signals will Molecule R show in the 13 C DEPT-135 spectrum? (a) 3 (b) 4 (c) 5 (d) 6 (e) 7 (f) 8 (g) 9 (h) 10 (i) 11 (j) Which of the following best matches the appearance of the carbon C in the 13 C DEPT-135 spectrum of R? (a) 128 (b) 123 (c) 114 (d) 114 (e) 30 (f) 42 (g) 42 (h) 65 (i) 65 (j) absent 4. Which of the following statements correctly reflects the relationship between H8 and H9 in the 1 H NMR spectrum of R? (assume couplings greater than 3 J are zero) (a) chemically and magnetically equivalent (b) chemically and magnetically nonequivalent (c) diastereotopic (d) chemically equivalent and magnetically nonequivalent (e) chemically nonequivalent and magnetically equivalent

3 CHEM 213 Midterm 2 Version A November 22, 2016 Page 3 of 8 5. Which choice represents ALL the carbons to which H10 shows long range HMQC (J = 10 Hz) for molecule R? (a) G (b) H (c) I (d) K (e) L (f) M (g) N (h) H and M (i) H and L (j) K and M 6. What is the predicted chemical shift of carbon-g in the 13 C NMR of R (using the data on page 1)? (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) What pattern is possible for H14 in the low temperature 1 H NMR spectrum of R? (a) s (b) d (c) t (d) q (e) pentet (f) sextet (g) dd (h) tt (i) d of pentet (j) dq 8. What is the chemical shift of H7 in the 1 H NMR of R? (using the data on page 1). (a) 8.47 (b) 7.94 (c) 7.89 (d) 7.49 (e) 7.37 (f) 6.35 (g) 6.55 (h) 6.65 (i) 7.17 (j) 7.27

4 CHEM 213 Midterm 2 Version A November 22, 2016 Page 4 of 8 Consider Molecule S when answering Questions Assume 4 J HF coupling is resolvable at about 3 Hz. 9. How many lines in total would you expect to observe in the 13 C DEPT-135 spectrum of S? (note, for example that a doublet is 2 lines in total while two doublets would be 4 lines in total). (a) 0 (b) 1 (c) 2 (d) 3 (e) 6 (f) 9 (g) 12 (h) 18 (i) 27 (j) What pattern(s) would you expect to see in the 19 F NMR spectrum of Molecule S at room temperature? (a) s (b) d (c) t (d) dd (e) ddd (f) two d (g) two dd (h) two t (i) four s (j) dddd 11. What is the appropriate spin system label for the coupled spins in Molecule S (ignore the H group in answering this)? (a) A 2 X 4 (b) A 2 B 4 (c) A 2 B 2 B 2 (d) AA B 2 B 2 (e) AA X 2 X 2 (f) AA X 4 (g) AA BB B B (h) AA MM XX

5 CHEM 213 Midterm 2 Version A November 22, 2016 Page 5 of 8 For EACH STRUCTURE below, DRAW your answer on the separate structure sheet. Compound AA C 11 H 15 N IR: 3390, 2738, 1708, 811 cm -1 [10 pts] 12. ne of these functional groups is present in Compound AA; which one is it? (note: there could be other unlisted functional groups present) (a) terminal alkyne (b) conjugated ketone (c) primary amide (d) secondary amide (e) secondary amine (g) meta-substituted aromatic 13. How many double bond equivalents are there in Compound AA? (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 (i) 8 (j) 9 1 H NMR: Note: the s at δ 3.9 becomes a triplet at low T 13 C NMR: DEPT-135 phasings shown Selected 1 H- 1 H CSY: δ 2.6 ppm with δ 9.75 and 2.8 ppm NTE: the H at δ 1.25 ppm does not show ANY long range HMQC correlations.

6 CHEM 213 Midterm 2 Version A November 22, 2016 Page 6 of 8 Compound AB C 10 H 16 2 [14 pts] IR: 1735 cm How many double bond equivalents are there in Compound AB? (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 (f) 5 (g) 6 (h) 7 (i) 8 (j) What functional group could be present in Compound AB from all the information given? (a) alkyne (b) ketone (c) aldehyde (d) ester (e) acid (f) alcohol (g) aromatic ring (h) trans-alkene 1 H NMR: 13 C{ 1 H} and DEPT-135

7 CHEM 213 Midterm 2 Version A November 22, 2016 Page 7 of 8 Short range HMQC (J = 135 Hz): 6.1 s (+) 4.3 t (-) 2.7 septet (+) 2.65 t (-) 2.5 t (-) 2.3 t (-) 1.15 d (+) Long range HMQC (J = 10 Hz): 6.1 s (-), 33.0(-), 24.3(-) 4.3 t (+), 122.6(x) 2.7 septet (-) 2.65 t (x), 40.4(+) 2.5 t (+), 24.3(-) 2.3 t (x), 147.9(+), 33.0(-) 1.15 d (x), 20.3(+) Don t forget to enter your structures for AA and AB on the separate structure sheets! THIS IS A BNUS QUESTIN: 1 H, 13 C{ 1 H and DEPT NMR data to select the correct structure for Molecule T and Enter your selection in the space provided on the separate structure answer sheet. [5 pts] 1 H NMR (300 MHz):

8 CHEM 213 Midterm 2 Version A November 22, 2016 Page 8 of 8 13 C{ 1 H} NMR with DEPT-135 phasing: Choices: A B C D E F G H I J K L Don t forget to enter your selection on the separate structure sheet! END