1 Chem 2320 Exam 1 January 30, 2006 Name: (Please print) (first) (last) Last 4 digits of I.D. ___ ___ ___ ___ Score I. Multiple Choice ( /20) /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? (a) C7H18Cl2 (b) C9H10Cl (c) C10H16Br2 (d) C11H14Br (e) None of the above2 2. Which molecule could have a strong IR absorption at around 1700 cm-1? OHClOIIIIIIIV (a) I (b) II (c) III (d) IV (e) None of the above How many types of peaks (signals) would you expect to see in the 1H or 13C NMR spectrum for the following compounds from questions 3 to 10? 3. (a) 2 (b) 3 (c) 4 (d) 5 (e) None of the above 4. (a) 3 (b) 4 (c) 5 (d) 6 (e) None of the above 5. (a) 2 (b) 3 (c) 4 (d) 5 (e) None of the above 6. (a) 2 (b) 3 (c) 4 (d) 5 (e) None of the above From 1H NMRBr From 13C NMRBr H ClHHHHHHFrom 1H NMRH HHHHHHClFrom 1H NMR3 7. (a) 3 (b) 4 (c) 5 (d) 6 (e) None of the above 8. (a) 4 (b) 5 (c) 6 (d) 7 (e) None of the above 9. (a) 4 (b) 5 (c) 6 (d) 7 (e) None of the above 10. (a) 3 (b) 4 (c) 5 (d) 6 (e) None of the above Answer questions 11 to 15 according to the 1H NMR of the following compound. H3CHHHHO HCH3H3COHaHdHbHcHe From 1H NMRNO2Cl From 13C NMRClNO2 From 1H NMRBr From 13C NMRBr4 11. From the 1H NMR, what proton dose the signal at 5 ppm (septet) correspond to? (a) Ha (b) Hb (c) Hc (d) Hd (e) He 12. From the 1H NMR, what proton dose the signal around 2.2 ppm (triplet) correspond to? (a) Ha (b) Hb (c) Hc (d) Hd (e) He 13. From the 1H NMR, what proton dose the signal around 1.6 ppm (multiple or sextet) correspond to? (a) Ha (b) Hb (c) Hc (d) Hd (e) He5 14. From the 1H NMR, what proton dose the signal around 1.2 ppm (doublet) correspond to? (a) Ha (b) Hb (c) Hc (d) Hd (e) He 15. From the 1H NMR, what proton dose the signal around 0.9 ppm (triplet) correspond to? (a) Ha (b) Hb (c) Hc (d) Hd (e) He Answer questions 16 to 18 according to the following spectra and compounds. Spectrum A NH2BrNH2NH2BrBrIIIIIIOCH3BrIVOCH3BrV6 Spectrum B Spectrum C 16. Which compound does spectrum A correspond to? (a) I (b) II (c) III (d) IV (e) V7 17. Which compound does spectrum B correspond to? (a) I (b) II (c) III (d) IV (e) V 18. Which compound does spectrum C correspond to? (a) I (b) II (c) III (d) IV (e) V 19. Base on the following enlarged signal from a 400 MHz 1H NMR spectrum, what could be the coupling constant(s) (a) 6.7 Hz and 13.3 Hz (b) 6.7 Hz (c) 13.3 Hz (d) 5 Hz (e) None of the above 20. How will you describe the splitting pattern (diagram) of the following signal (Ha) from 1H NMR? (a) sextet (b) triplet of doublet (c) triplet (d) doublet (e) None of the above Continue to the Next Page 3.2 ppm3.3 ppm15 mm5 mm2.5 mm400 MHz 1H NMRintegral ratio of peaks:1:3:3:1 integral ratio:1 : 2 : 1 : 1 : 2 :1Ha8 II. For the indicated protons (Ha, Hb, and Hc) of the compound below, draw the splitting patterns (diagrams) according to the given coupling constants (J values) from 1H NMR (5 points each, 15 point total). Continue to the Next Page BrHcHbHaJab = 2 HzJac = 15 HzJbc = 7 Hz9 III. Provide your analysis and answers for the following questions based on the given spectroscopic information. Please provide your analysis on 1H and 13C NMR. You may get partial credits even your proposed structure is incorrect. (25 points)10 *From Mass Spec: M+ = 194. *From elemental analysis: C: 68.1%; H: 7.2%. *From 1H NMR: One proton with chemical shift at 12 ppm is not showed in the given 1H 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 Page11 3. Your analysis from 1H NMR. Please write clearly how you interpret the chemical shifts and splitting diagrams. (8 points) Continue to the Next Page12 4. Your analysis from 13C 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