Chem 2320 Exam 1 January 30, 2006 Name: (first) (last) (Please print) Last 4 digits of I.D. I. Multiple Choice ( /20) Score /60 II /15 III /25 Total score /100 I. Multiple choice questions. (3 points each). Please put your answers on Scantron sheet. Your score will be graded based only on your answers from Scantron sheet. 1. Which molecular formula has molecular ions ration as: M + /[M+2] + =1/1? C 7 18 Cl 2 C 9 10 Cl C 10 16 2 C 11 14 1
2. Which molecule could have a strong IR absorption at around 1700 cm -1? Cl I O O II III IV I II III IV None of the above ow many types of peaks (signals) would you expect to see in the 1 or 13 C NMR spectrum for the following compounds from questions 3 to 10? 3. From 1 NMR Cl 2 3 4 5 4. Cl From 1 NMR 3 4 5 6 5. From 1 NMR 6. 2 3 4 5 From 13 C NMR 2 3 4 5 2
7. Cl NO 2 From 1 NMR 3 4 5 6 8. NO 2 Cl From 13 C NMR 4 5 6 7 9. From 1 NMR 4 5 6 7 10. From 13 C NMR 3 4 5 6 Answer questions 11 to 15 according to the 1 NMR of the following compound. c a 3 C O e O 3 C C 3 b d 3
11. From the 1 NMR, what proton dose the signal at 5 ppm (septet) correspond to? a b c d e 12. From the 1 NMR, what proton dose the signal around 2.2 ppm (triplet) correspond to? a b c d e 13. From the 1 NMR, what proton dose the signal around 1.6 ppm (multiple or sextet) correspond to? a b c d e 4
14. From the 1 NMR, what proton dose the signal around 1.2 ppm (doublet) correspond to? a b c d e 15. From the 1 NMR, what proton dose the signal around 0.9 ppm (triplet) correspond to? a b c d e Answer questions 16 to 18 according to the following spectra and compounds. N 2 I II III OC 3 N 2 N 2 IV OC 3 V Spectrum A 5
Spectrum B Spectrum C 16. Which compound does spectrum A correspond to? I II III IV V 6
17. Which compound does spectrum B correspond to? I II III IV V 18. Which compound does spectrum C correspond to? I II III IV V 19. Base on the following enlarged signal from a 400 Mz 1 NMR spectrum, what could be the coupling constant(s) 2.5 mm 5 mm 400 Mz 1 NMR integral ratio of peaks: 1:3:3:1 6.7 z and 13.3 z 6.7 z 13.3 z 5 z None of the above 3.3 ppm 15 mm 3.2 ppm 20. ow will you describe the splitting pattern (diagram) of the following signal ( a ) from 1 NMR? a sextet triplet of doublet triplet doublet None of the above integral ratio: 1 : 2 : 1 : 1 : 2 :1 Continue to the Next Page 7
II. For the indicated protons ( a, b, and c ) of the compound below, draw the splitting patterns (diagrams) according to the given coupling constants (J values) from 1 NMR (5 points each, 15 point total). a b c Jab = 2 z J ac = 15 z J bc = 7 z Continue to the Next Page 8
III. Provide your analysis and answers for the following questions based on the given spectroscopic information. Please provide your analysis on 1 and 13 C NMR. You may get partial credits even your proposed structure is incorrect. (25 points) 9
*From Mass Spec: M + = 194. *From elemental analysis: C: 68.1%; : 7.2%. *From 1 NMR: One proton with chemical shift at 12 ppm is not showed in the given 1 NMR. 1. What is the molecular formula? (3 points) 2. From the IR spectrum, is there a carbonyl group (C=O)? (2 points) Continue to the Next Page 10
3. Your analysis from 1 NMR. Please write clearly how you interpret the chemical shifts and splitting diagrams. (8 points) Continue to the Next Page 11
4. Your analysis from 13 C NMR. (4 points) 5. Your proposed structure (4 points) 6. If your proposed structure contains a carbon-carbon double bond (C=C), please show your calculation of coupling constant (J value), and explain your assignment of cis and trans isomer. (4 points) 12