CHEM 242 UV-VIS SPECTROSCOPY, IR SPECTROSCOPY, CHAP 13A ASSIGN AND MASS SPECTROMETRY C 8 H 17 A B C

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1 CEM 242 UV-VIS SPECTRSCPY, IR SPECTRSCPY, CAP 13A ASSIGN AND MASS SPECTRMETRY 1. Which choice matches the max of each steroid in the order given? C 8 17 C 8 17 C 8 17 A B C A. 209 nm 241 nm 284 nm B. 241 nm 284 nm 206 nm C. 284 nm 241 nm 206 nm D. 284 nm 206 nm 241 nm 2. Select the most energetically favorable UV transition for 1,3-butadiene. A. n * B. n * C. 2 3* D. * E. 1 4* 3. The IR stretching frequency occurs at the lowest frequency for which of these bonds? A. B B. - C. N- D. S- E. Difficult to predict 4. An oxygen-containing compound shows strong IR absorption at cm -1 and cm -1. What type of compound is it likely to be? A. An alcohol B. A carboxylic acid C. An ether D. A ketone E. An aldehyde 5. A split peak for the IR absorption due to bond stretching is observed for the carbonyl group in which of these compounds? A. C 3C 2 C 2 C B. C 3C 2 CCl C. C 3C 2 CN 2 D. C 3C 2 CC 2 C 3 E. C 3C 2 CCC 2 C 3 6. The IR stretching frequency can be predicted to occur at the highest frequency for which of these bonds? A. C B. C F C. C Cl D. C Br E. C I 7. An anticipated IR absorption band may not be observed because: A. it occurs outside the range of the instrument used. B. no change occurs in the dipole moment during the vibration. C. the absorption band is eclipsed by another. D. the intensity is so weak that it cannot be differentiated from instrument noise. E. All of these 1

2 8. IR evidence for the presence of the C=C would be most difficult to detect in the case of which of these alkenes? A B C D E 9. The IR absorption due to the stretching of which of these carbon-hydrogen bonds occurs at the highest frequency? A. I B. II C. III D. IV E. V I II III IV V 10. The IR spectrum of which type of compound generally exhibits evidence of hydrogen bonding? A. Aldehyde B. Carboxylic acid C. Alkene D. Ester E. Ketone 11. Which of the following molecules most likely generated this IR spectral data? Wavenumber (cm -1 ) 3300 (broad), 3000, 2200, 2100, 1700 Note: This only includes selected peaks. A. B. C. D. E. 12. Which compound would be expected to show intense IR absorption at 2820, 2710 and 1705 cm-1? A. C3CC2C3 B. PhCC3 C. PhC D. C2=CCC3 13. Which compound would be expected to show intense IR absorption at 2250 cm-1? A. C3C2C2C2 B. (C3)2CC2 C. (C3)2CCN D. C3C2C2CN2 14. Which compound would be expected to show intense IR absorption at 1746 cm-1? A. C3C2C2C3 B. C3C2CN C. C3C2C2C3 D. C3C2SC3 2

3 15. Which compound would be expected to show intense IR absorption at 1680 cm- 16. Ethyne (C C) does not show IR absorption in the region cm-1 because: A. C stretches occur at lower energies. B. C C stretches occur at about 1640 cm-1. C. there is no change in the dipole moment when the C C bond in ethyne stretches. D. there is a change in the dipole moment when the C C bond in ethyne stretches. 17. Which of the following would not have a C stretch at about 3050 cm-1? A. 1-pentene B. 2-pentene C. 2-methyl-2-pentene D. 2,3-dimethyl-2-pentene E. 2,4-dimethyl-2-pentene 18. Which of the following stretches tends to be the least intense? A. (alcohol) B. (carboxylic acid) C. C D. C= E. C=C 19. Which of the following does not have a broad absorption with one or more spikes that is centered about 3300 cm-1 in the IR? A. (C3C2C2)3N B. (C3C2C2)2N C. C3C2C2N2 D. (C3)3CN2 E. (C2=CC2)2N 20. Which compound would be expected to show intense IR absorption at 3367, 3282 cm-1? A. but-1-ene B. PhC2 C. C3C2C3 D. PhC2N2 21. Which compound would be expected to show intense IR absorption at 1640 cm-1? A. hex-1-ene B. 2-methylheptane C. C3C2C2 D. C3C2CC3 22. The frequency of the stretching vibration of a bond in IR spectroscopy depends on what two quantities? A. the stiffness of the bond and the electronegativity of the atoms B. the electronegativity of the atoms and the nuclear charges of the atoms C. the masses of the atoms and the stiffness of the bond D. the nuclear charges of the atoms and the atomic radii E. the electronegativity of the atoms and the masses of the atoms 23. Which of the following has a C stretch that occurs at the highest stretching frequency? A. hexane B. hex-1-ene C. (E)-hex-2-ene D. hex-1-yne E. hex-2-yne 24. Which compound would show a larger than usual M+2 peak in the mass spectrum? A. C3C2SC3 B. (C3)2CN2 C. C3C2C2 D. C3(C2)2C3 3

4 25. Which of the following structures is consistent with the IR spectra shown below? A. B. C. D. E. 26. When a high energy electron impacts molecule M in the ionization chamber, what type of species is initially produced? A. cation B. anion C. radical D. radical cation E. radical anion 27. The mass spectrum of alcohols often fail to exhibit detectable M peaks but instead show relatively large peaks. A. M+1 B. M+2 C. M-16 D. M-17 E. M The two most abundant isotopes of boron are 10B and 11B, with 11B being about 4 times more abundant. In the mass spectrum of trimethylborate [(C3)3B],. A. the peaks at m/z 103 and m/z 104 have equivalent intensities B. the peak at m/z 103 has an intensity which is 4 times that of the m/z 104 peak C. the peak at m/z 103 has an intensity which is 1/4 the intensity of the peak at m/z 104 D. none of the above 29. What m/z characterizes a strong peak in the mass spectrum of cyclopentanol? A. 86 B. 85 C. 84 D. 70 E Which is the base peak? A. 15 B. 29 C. 44 D. 45 E. 100 Use the following to answer questions Which is the likely molecular ion (M )? A. 15 B. 29 C. 44 D. 45 E Select the structure of a compound C 6 14 with a base peak at m/z 43. A. C 3C 2C 2C 2C 2C 3 B. (C 3C 2) 2CC 3 C. (C 3) 3CC 2C 3 D. (C 3) 2CC(C 3) 2 E. None of these 4

5 33. Which of the following structures is consistent with the mass spectrum shown below? A) B) C) D) E) 34. What is the molecular formula of this compound? m/z intensity 84 M A. C 5 10 B. C 5 8 C. C 5 24 D. C 6 12 E. C EXTRA CREDIT 35. Which of the following compounds has the lowest carbonyl stretching frequency? A B C D 36. Which of the following fragment peaks would not be present in the mass spectrum of n-hexane? A. 87 B. 71 C. 57 D. 43 E Predict the base peak for 2-chloro-2-methylpropane A. m/z 15 B. m/z 92 C. m/z 43 D. m/z 57 E. m/z 77 5

6 NAME DATE ANSWER SEET CEM 242 CAP 13A ASSIGN SP