St. John’s University Department of ChemistryChemistry 2240 2/25/03Departmental Examination #1 Version 1

NAME _________________________ Last 4 digits, StormCard #__________

I DO DO NOT WANT MY GRADE POSTED

INSTRUCTOR'S NAME (Circle one): Cesare Graham Kalas

THERE ARE TWELVE (12) PAGES TO THIS EXAM

INSTRUCTIONS

1. Write your name and the last 4 digits of your StormCard on this page and on the answer (scantron) sheet.

2. Use the examination pages and the blank scrap page to work out your answers.3. For each of the 25 questions, indicate the correct answer on the scantron with a # 2

pencil. Each question is worth four points.4. You may use your molecular model set. NO OTHER MATERIALS ARE PERMITTED.5. Hand in the examination questions and the scantron sheet.6. You will have 90 minutes to complete the exam.

Remember: There is only ONE answer that BEST answers the question.

PROPER CONDUCT DURING EXAMS:

1. Communication between students by any means is prohibited.2. Possession of any unauthorized papers is prohibited.3. No paging devices or cell phones are allowed.

MAKE SURE THEY ARE TURNED OFF AND PUT AWAY4. All books, papers, and jackets should be placed in the front/sides of the room.5. Violation of any of the above rules will result in a grade of zero.

1) Which of the following m/z values corresponds to the molecular ion for benzyl alcohol?

a) 17 b) 52c) 91 d) 108

2) Which of the following compounds would have three signals in its 1H NMR spectrum?

3) What diene and dienophile would be used to synthesize the Diels/Alder product shown on the right?

4) Which of the following compounds represents a phenol?

5) What can we say regarding the intensity of the M+2 ion in the mass spectrum of ethyl chloride, CH3CH2Cl? (the two isotopes of Cl are 35Cl and 37Cl)

a) The M+2 ion will occur at m/z = 66 and will be one-third the intensity of the ion at m/z = 64.b) The M+2 ion will occur at m/z = 64 and will be as intense as the ion at m/z = 64.c) The M+2 ion will occur at m/z = 66 and will be three times as intense as the ion at m/z = 64.d) Ethyl chloride would not show an M+2 ion.

6) What splitting pattern is observed in the proton NMR spectrum for the indicated hydrogens?

a) Singlet b) Doubletc) Triplet d) Quartet

7) A diene of unknown structure reacts with HBr to give two products, A and B. At 40 oC, compound A is the major product and at –80 oC compound B is the major product. Thermodynamic data shows that compound A is the more stable product. We can say…

a) We can only say that A is the kinetic product.b) We can only say that B is the thermodynamic product.c) We can say that A is the thermodynamic product and that B is the kinetic product.d) We can say that A is the kinetic product and that B is the thermodynamic product.

8) What is the correct name for the following compound?

a) o-Nitro-m-bromotolueneb) 3-Bromo-6-nitrotoluenec) p-Bromo-o-nitrotoluened) 5-Bromo-2-nitrotoluene

9) You observe a molecular ion at m/z = 98 in the mass spectrum of an unknown compound. What is a possible molecular formula?

a) C6H10O b) C7H12Oc) C7H12 d) CH3Br

10) How many signals would you see in principle in the 13C NMR spectrum of toluene?

a) 2 b) 3c) 4 d) 5

11) What are the two major products for the reaction shown at right?

a) W and X b) Y and Zc) X and Z d) W and Y

12) Which of the following molecules or ions are aromatic?

a) all of them b) W, X, Y, and Zc) only Z d) only V

13) Which compound would be expected to show IR absorption at 2250 cm-1?

14) Which of the following spectroscopic clues is evidence for the acyl group, CH3CO– ?

a) a peak at approximately 1710 cm-1 in an IR spectrum.b) a signal at approximately = 180 ppm in a 13C NMR spectrum.c) a signal in a 1H NMR spectrum at approximately = 2.1 ppm that

integrates to 3H.d) They are all clues to the presence of an acyl group.

15) Which of the dienes shown below would be an especially poor diene to use in a Diels/Alder reaction?

16) An unknown compound has the formula C3H5Cl3. Its proton NMR spectrum consists of a singlet at = 2.2 ppm and a singlet at = 4.0 ppm. What is the structure of this unknown compound?

a) CCl3CH2CH3 b) CHCl2CHClCH3

c) CHCl2COCH2Cl d) CH2ClCCl2CH3

17) Which of the molecules shown below would show only singlets in its 1H NMR spectrum?

a) only W. b) only X.c) only Y and Z. d) only W and X.

18) Which statement concerning the dienes shown below is true?

a) all three dienes are conjugated dienes.b) all three dienes are isolated dienes.c) X and Z are isolated dienes and Y is a conjugated diene.d) X and Z are conjugated dienes and Y is a isolated diene.

19) Which nitrogen is the LEAST basic in the purine derivative shown on the right?

a) N1 b) N3

c) N7 d) N9

20) Which of the following statements best explains the information we can gain from infrared spectroscopy?

a) It allows us to determine the number of protons in a compound.b) It allows us to determine the kinds of functional groups in a compound, based on the

frequency at which bonds stretch or bend.c) It allows us to determine the molecular weight and the mass of some fragments of a

compound.d) It allows us to determine the number of carbons in a compound.

21) Which of the following spectroscopic clues is evidence for an alcohol hydroxyl group, R–OH?

a) a signal in a 1H NMR spectrum that disappears when D2O is added.b) a molecular ion:M+2 (M:M+2) ratio of approximately 1:1 in a mass spectrum.c) a peak at approximately 3000 cm-1 in an IR spectrum.d) They are all clues to the presence of an alcohol –OH group.

22) Which of the following would NOT be a product in the reaction shown below?

23) Which of the following statements concerning benzene are true?

a) All the carbon-carbon bonds in benzene are the same length, and are shorter than carbon-carbon single bonds but longer than carbon-carbon double bonds.

b) When benzene is hydrogenated to cyclohexane, the amount of heat given off is approximately three times as much as when cyclohexene is hydrogenated to cyclohexane.

c) It exists as a rapidly equilibrating mixture of the two compounds shown below.

d) All of the above are true.

24) Determine the structure of the organic compound (C7H14O) that gave the MS, IR, and 1H NMR spectra shown below. In addition, the 13C NMR spectrum had the following signals: = 214.4, 40.2, and 17.3 ppm.

25) What is the structure of the compound whose IR and 1H NMR spectra are given below?