Deck 10: Determining the Structure of Organic Compounds

Question 1

Which of the following solvents is the best one to use when taking an IR spectrum? I. Water, $\mathrm { H } _ { 2 } \mathrm { O }$
II. Carbon tetrachloride, $\mathrm { CCl } _ { 4 }$
III. Methanol, $\mathrm { CH } _ { 3 } \mathrm { OH }$
IV. Ethanol, $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OH }$
V. Benzene,

A) I
B) II
C) III
D) IV
E) V

Answer 1

II

Question 2

Which statements are true about the mass spectrum of 1-bromobutane?

A) Peaks of approximately equal intensity are observed at m/z 136 and 138 .
B) The major fragmentation occurs by cleavage of the C-Br bond.
C) The most intense peak occurs at m/z 43 .
D) both A and B
E) both B and C

Answer 2

both A and B

Question 3

Which compound's mass spectrum shows peaks at M, M+2 , and M+4 with abundances in a ratio of 1:2:1?

A) cyclohexanol
B) chlorocyclohexane
C) 1,2 -dichlorocyclohexane
D) 1-bromopentane
E) 1,5 -dibromopentane

Answer 3

1,5 -dibromopentane

Question 4

Which statement is not true about electromagnetic radiation?

A) Frequency is directly proportional to wavelength.
B) All molecules absorb electromagnetic radiation at some frequency.
C) Frequency is inversely proportional to wavelength.
D) Energy is directly proportional to frequency.
E) Energy is inversely proportional to wavelength.

Question 5

Which of the following m/z values is the least intense in the mass spectrum of 1- chloropropane?

A) 80
B) 79
C) 78
D) 65
E) 63

Question 6

Which statement is true about the base peak in mass spectrometry?

A) Its m/z value is the same as the molecular weight of the compound.
B) Its m/z value corresponds to a very stable carbanion.
C) It is the tallest peak in the spectrum.
D) It has the largest m/z value of all the peaks in the spectrum.
E) The base peak is assigned a relative abundance equal to that of the parent ion.

Question 7

In the mass spectrum of 2-chloropropane, what is the m/z value of the molecular ion ?

A) 63
B) 76
C) 78
D) 80
E) 82

Question 8

What region of the electromagnetic spectrum has the greatest energy per photon?

A) visible
B) microwave
C) radio
D) ultraviolet
E) infrared

Question 9

Which of the following m/z values is that for the molecular ion of the following compound?

A) 15
B) 29
C) 43
D) 57
E) 72

Question 10

What is the m/z value of the base peak of the following compound?

A) 77
B) 92
C) 15
D) 57
E) 43

Question 11

Which of the following will have a base peak of 43 in its mass spectrum?

A)
B) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 }$
C)
D)
E) none of the above

Question 12

Which molecular change is necessary for mass spectrometry?

A) excitation of an electron from the ground state to higher energy state
B) change of alignment of an electron in a magnetic field
C) change of alignment of a proton in a magnetic field
D) loss of an electron
E) molecular vibration

Question 13

Which of the following is not a major peak in the mass spectrum of isopentane?

A) 29
B) 43
C) 57
D) 60
E) 72

Question 14

Which statement describes the following species?
$\left[ \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 } \right] \cdot +$

A) It is the molecular ion of propane.
B) It represents propane after it has lost an electron.
C) It is the radical cation of propane.
D) The m/z value is 44 .
E) All of the above

Question 15

In the mass spectrum of 1,2-dichloroethane, what is the m/z value of the molecular ion ?

A) 94
B) 96
C) 98
D) 100
E) 102

Question 16

Which statement explains the information we can gain from mass spectrometry?

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.
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 presence and nature of a carbocation in the compound.
E) It allows us to determine the presence and nature of a free radical in the compound.

Question 17

Which statement about a molecular ion is true?

A) It is a compound that lost a pair of electrons.
B) It is a compound that gained a pair of electrons.
C) It is a compound that gained one electron.
D) It is a compound that lost one electron.
E) It is a compound that carries a free radical and a negative charge.

Question 18

Which of the following is characteristic of the mass spectrum of an alkyl chloride?

A) an intense M+1 peak
B) an intense M+2 peak
C) base peak
D) parent peak
E) none of the above

Question 19

In the electromagnetic spectrum, ________ frequencies, ________ wavenumbers, and ________ wavelengths are associated with high energy.

A) high; small; long
B) low; large; short
C) low; small; short
D) high; large; short
E) high; small; short

Question 20

Which statement explains how a hydrocarbon can show a M+2 peak?

A) from ¹³C and ¹ H
B) from ¹²C and ²H
C) from a single ¹³C
D) from a single ³H
E) from two ¹³C's

Question 21

Which compound shows the highest carbonyl absorption frequency?

A) amide
B) ester
C) ketone
D) aldehyde
E) ether

Question 22

Which of the following shows a broad absorption at 3200-3500 cm^-1 in its IR spectrum?

A) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CN }$
B) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm {~N} \left( \mathrm { CH } _ { 3 } \right) _ { 2 }$
C) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CO } _ { 2 } \mathrm { CH } _ { 3 }$
D) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { OH }$
E) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OCH } _ { 3 }$

Question 23

Which of the following $\mathrm { C } - \mathrm { H }$ bonds shows IR absorption at the lowest wavenumber? I.
II.

III. $\mathrm { C } - \mathrm { C } - \mathrm { H }$
IV. $\mathrm { C } = \mathrm { C } - \mathrm { H }$
V. $\mathrm { C } \equiv \mathrm { C } - \mathrm { H }$

A) I
B) II
C) III
D) IV
E) V

Question 24

At what wavenumber does a C-H stretch occur when the carbon is sp hybridized?

A) 2700 cm^-1
B) 2900 cm^-1
C) 3100cm^-1
D) 3300cm^-1
E) 3500 cm^-1

Question 25

Which statement 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.
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 presence of a carbocation in the compound.
E) It allows us to determine the presence of a radical in the compound.

Question 26

Which compound shows the lowest carbonyl absorption frequency?

A) ester
B) ketone
C) amide
D) aldehyde
E) carboxylic acid

Question 27

Which of the following compounds has a significant IR absorption band at 3400 cm^-1?

A) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { OH }$
B) $\mathrm { CH } _ { 3 } \mathrm { C } \equiv \mathrm { CCH } _ { 2 } \mathrm { CH } _ { 3 }$
C) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } \left( \mathrm { NH } _ { 2 } \right) \mathrm { CH } _ { 3 }$
D) $\left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm {~N}$
E) $\mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 }$

Question 28

Which compound shows an intense absorption at $2250 \mathrm {~cm} ^ { - 1 }$ ?

A) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CO } _ { 2 } \mathrm { H }$
B) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CN }$
C) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { OH }$
D) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CONH } _ { 2 }$

Question 29

The absorption of a C=C bond occurs at

A) 1650 cm^-1
B) 2100 cm^-1
C) 1100 cm^-1
D) 3300 cm^-1
E) 2850 cm^-1

Question 30

Which of the following compounds has an intense IR absorption band at 1715 cm^-1?

A) CH₃CH₂CO₂H
B) 1-hexene
C) 2-methylhexane
D) CH₃CH₂CH₂NH₂

Question 31

Which of the following compounds has a significant IR absorption band at 2220cm^-1?

A) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { OH }$
B) $\mathrm { CH } _ { 3 } \mathrm { C } \equiv \mathrm { CCH } _ { 2 } \mathrm { CH } _ { 3 }$
C) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } \left( \mathrm { NH } _ { 2 } \right) \mathrm { CH } _ { 3 }$
D) $\left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm {~N}$
E) $\mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 }$

Question 32

Which of the following compounds has an intense IR absorption band at 1746 cm^-1?

A) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { OCH } _ { 2 } \mathrm { CH } _ { 3 }$
B) $\mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } \mathrm { CH } _ { 3 }$
C) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CCH }$
D) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { SCH } _ { 3 }$

Question 33

Which compound's carbonyl stretch occurs at the greatest wavenumber?

A) CH₃CH₂CH₂CHO
B) CH₃COCH₂CH₃
C) CH₃CH₂CONH₂
D) CH₃CH₂CO₂CH₃
E) CH₃CH₂COCH₂CH₃

Question 34

Which compound shows an intense absorption at 2710 and 1705 cm^-1?

A) $\mathrm { CH } _ { 3 } \mathrm { COCH } _ { 2 } \mathrm { CH } _ { 3 }$
B) $\mathrm { PhCOCH } _ { 3 }$
C) $\mathrm { PhCHO }$
D) $\mathrm { CH } _ { 2 } = \mathrm { CHCOCH } _ { 3 }$

Question 35

Which of the following compounds has a significant absorption band in the 1720 - 1780 cm^-1 range of its IR spectrum?

A) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { OH }$
B) $\mathrm { CH } _ { 3 } \mathrm { C } \equiv \mathrm { CCH } _ { 2 } \mathrm { CH } _ { 3 }$
C) $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } \left( \mathrm { NH } _ { 2 } \right) \mathrm { CH } _ { 3 }$
D) $\left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm {~N}$
E) $\mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 }$

Question 36

Which of the following has an absorption band at 1250 cm^-1 in its IR spectrum?

A) CH₃CH₂CN
B) CH₃CH₂N(CH₃)₂
C)CH₃CH₂CO₂CH₃
D) CH₃CH₂CH₂OH
E) CH₃CH₂OCH₃

Question 37

Which of the following bonds shows absorption at the lowest wavenumber?

A) C=O
B) C-O
C) O-H in alcohol
D) N-H
E) C=N

Question 38

Which compound's carbonyl stretch occurs at the lowest wavenumber?

A) CH₃CH₂CH₂CHO
B) CH₃COCH₂CH₃
C) CH₃CH₂CONH₂
D) CH₃CH₂CO₂CH₃
E) CH₃CH₂COCH₂CH₃

Question 39

Which of the following compounds exhibits no IR absorption at 1630-1780 cm^-1 or at 3200-3550 cm^-1?

A) an alcohol
B) an amide
C) a ketone
D) an aldehyde
E) an ether

Question 40

Which of the following carbonyl groups exhibits an absorption band at the highest wavenumber?

A) I
B) II
C) III
D) IV
E) V

Question 41

Which of the following compounds has the greatest λ_max ?

A) benzene
B) phenol
C) phenolate ion
D) aniline
E) anilinium ion

Question 42

Which of the following compounds has the greatest λ_max ?

A) 1-decene
B) 1,3-decadiene
C) 1,3,5 -decatriene
D) 1,4 -decadiene
E) 1,3 ,5,7 -decatetraene

Question 43

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 44

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 45

Which of the following spectroscopic techniques uses the lowest energy of the electromagnetic spectrum?

A) UV
B) visible
C) IR
D) X-ray
E) NMR

Question 46

Which of the following compounds give an absorption band at 1720 cm^-1 and none at 2720 - 2830 or 3400 cm^-1?

A) 2-butanone
B) butanal
C) cis-2-butene
D) trans-2-butene
E) 1-butanol

Question 47

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 2
B) 4
C) 3
D) 5
E) 6

Question 48

Which of the following compounds exhibits the highest $\lambda _ { \max }$ in its UV spectrum? I.

II.
11ee0445_2138_a9f9_854b_6d15d16f4d84_TB1829_11
III.

IV.

V.

A) I
B) II
C) III
D) IV
E) V

Question 49

1H nuclei located near electronegative atoms tend to be ________ relative to ¹H nuclei that are not.

A) shielded
B) deshielded
C) resonanced
D) split
E) none of the above

Question 50

Which compound has an absorption band at 3300 cm^-1?

A) 1-pentene
B) cyclohexane
C) 2-heptyne
D) 1-pentyne
E) diethyl ether

Question 51

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 2
B) 5
C) 1
D) 4
E) 3

Question 52

The pKa of a compound whose acidic or basic form absorbs UV or visible light can be determined spectroscopically because ________.

A) λ_max always decreases as the acidic form is converted to the basic form
B) the pKa is the same as the pH at which half of the total absorbance increase occurs
C) absorbance of the basic form is always twice that of the acidic form
D) absorbance of the acidic form is always twice that of the basic form
E) delocalization always leads to a decrease in acidity

Question 53

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 6
B) 3
C) 5
D) 4
E) 2

Question 54

How many signals would you expect to see in the ¹H NMR spectrum of the following compound? CH₃CH₂CH₂CH₃

A) 1
B) 3
C) 2
D) 4
E) 6

Question 55

Which of the following compounds absorbs the longest wavelength of UV visible light?

A) (E) -2-butene
B) (Z) -2-butene
C) 1-hexene
D) (Z)-1,3 -hexadiene
E) (E)-1,3,5 -hexatriene

Question 56

Which compound has absorption bands at 2720 cm^-1 and 2820 cm^-1?

A) CH₃COCH₂CH
B) CH₃CH₂CO₂CH₃
C)CH₂=CHCH₂CH₃
D)CH₃CH₂CH₂CHO
E)CH₃CH₂CH₂OH

Question 57

Which of the following types of electromagnetic radiation is used in NMR spectroscopy?

A) X-ray
B) infrared
C) visible
D) radio
E) ultraviolet

Question 58

Which compound shows IR absorption at 3300 cm^-1 ?

A) (CH₃)₂CHCCH
B)(CH₃)₂CHN(CH₃)₂
C) (CH₃)₂CHCCCH₃
D) (CH₃)₂CHCH=CH₂
E)(CH₃)₂CHCO₂CH₃

Question 59

Which compound has two absorption bands between 3300-3500 cm^-1 ?

A) (CH₃)₃N
B) CH₃CH₂NHCH₃
C) CH₃CH₂NH₂
D)CH₃CON(CH₃)₂
E)CH₃OCH₂CH₂N(CH₃)₂

Question 60

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 5
B) 4
C) 2
D) 3
E) 1

Question 61

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 7
B) 3
C) 4
D) 2
E) 8

Question 62

Which of the following methyl groups gives the ¹H NMR signal with the highest frequency? $\begin{array} { l l l l } \text { I. } & \mathrm { CH } _ { 3 } \mathrm { NH } _ { 2 } & \text { IV. } & \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 } \end{array}$
II. $\mathrm { CH } _ { 3 } \mathrm { OH }$
III.

V.

A) I
B) II
C) III
D) IV
E) V

Question 63

Which of the following compounds gives the ¹H NMR signal with the highest frequency? I. $\left( \mathrm { CH } _ { 3 } \right) _ { 4 } \mathrm { C }$ .
II. $\left( \mathrm { CH } _ { 3 } \right) _ { 4 } \mathrm { Si }$
III. $\left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { Ni }$
IV.

V.

A) I
B) II
C) III
D) IV
E) V

Question 64

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 1
B) 2
C) 4
D) 5
E) 3

Question 65

Describe the difference between a ketone and an aldehyde in an ¹H NMR spectrum.

A) An aldehyde has a signal at 9.0-10.0 ppm
B) An aldehyde has a signal at 2.1 ppm
C) An aldehyde has a signal at 5.0 ppm
D) An aldehyde has a signal at 3.5 ppm
E) An aldehyde has a signal at 8.0 ppm

Question 66

What is the ratio of the protons in the following compound?

A) 3:3:2
B) 3:2
C) 6:2:1
D) 3:1
E) 3:2:1

Question 67

How many signals does the ¹H NMR spectrum of isopentylamine have?

A) 2
B) 3
C) 4
D) 5
E) 6

Question 68

How many signals does the ¹H NMR spectrum of 4-methyl-1-propylbenzene have?

A) 4
B) 5
C) 6
D) 7
E) 8

Question 69

What splitting pattern is observed in the ¹H NMR spectrum for the indicated hydrogens?

A) singlet
B) doublet
C) triplet
D) quartet
E) septet

Question 70

What is the integration for each proton in the ¹H NMR spectrum of the following compound?

A) $\mathrm { a } = 2 \mathrm { H } ; \mathrm { b } = 3 \mathrm { H } ; \mathrm { c } = 2 \mathrm { H } ; \mathrm { d } = 3 \mathrm { H } ; \mathrm { e } = 2 \mathrm { H }$
B) $\mathrm { a } = 2 \mathrm { H } ; \mathrm { b } = 3 \mathrm { H } ; \mathrm { c } = 2 \mathrm { H } ; \mathrm { d } = 5 \mathrm { H } ; \mathrm { e } = 2 \mathrm { H }$
C) $\mathrm { a } = 5 \mathrm { H } ; \mathrm { b } = 5 \mathrm { H } ; \mathrm { c } = 7 \mathrm { H } ; \mathrm { d } = 7 \mathrm { H } ; \mathrm { e } = 7 \mathrm { H }$
D) $a = 3 H : b = 2 H : c = 2 H : d = 2 H : e = 3 H$
E) $\mathrm { a } = 3 \mathrm { H } ; \mathrm { b } = 2 \mathrm { H } ; \mathrm { c } = 2 \mathrm { H } ; \mathrm { d } = 3 \mathrm { H } ; \mathrm { e } = 2 \mathrm { H }$

Question 71

How many signals would you expect to see in the ¹H NMR spectrum of the following compound? ClCH₂CH₂Cl

A) 5
B) 4
C) 3
D) 2
E) 1

Question 72

What splitting pattern is observed in the ¹H NMR spectrum for the indicated hydrogens?

A) singlet
B) doublet
C) triplet
D) quartet
E) septet

Question 73

What splitting pattern is observed in the ¹H NMR spectrum for the indicated hydrogens?

A) singlet
B) doublet
C) triplet
D) quartet
E) septet

Question 74

What hydrogens give the ¹H NMR signal with the highest frequency? $\mathrm { F } - \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } - \mathrm { Br }$
$\begin{array} { l l l l l } \quad\quad1 & 2 & 3 & 4 & 5 \end{array}$

A) 1
B) 2
C) 3
D) 4
E) 5

Question 75

What hydrogens give the ¹H NMR signal with the highest frequency? $\left( \mathrm { CH } _ { 3 } \right) _ { 2 } \mathrm { CH } - \mathrm { O } - \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 }$
$\begin{array} { l l l l l }\quad 1 & \quad2 &\quad 3 &\quad 4 & 5 \end{array}$

A) 1
B) 2
C) 3
D) 4
E) 5

Question 76

What hydrogens give the ¹H NMR signal with the lowest frequency? $\mathrm { F } - \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } - \mathrm { Br }$
$\begin{array} { l l l l l } \quad\quad1 & 2 & 3 & 4 & 5 \end{array}$

A) 1
B) 2
C) 3
D) 4
E) 5

Question 77

How many signals would you expect to see in the ¹H NMR spectrum of the following compound?

A) 1
B) 2
C) 4
D) 3
E) 6

Question 78

How many singlets will the ¹H NMR spectrum of 2 -bromo- 3 -methyl-2-butene exhibit?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 79

What is the ratio of the protons in the following compound?

A) 3:3:3:2
B) 6:3:2
C) 9:2
D) 3:2
E) 6:2

Question 80

What hydrogens give the ¹H NMR signal with the lowest frequency?

A) 1
B) 2
C) 3
D) 4
E) 5