Deck 11: Alkenes: Infrared Spectroscopy and Mass Spectrometry

Question 1

What would be the proper name of the following?

A) (Z)-3-chloro-2-pentene
B) (Z)-3-chloro-3-pentene
C) (E)-3-chloro-2-pentene
D) (E)-3-chloro-3-pentene
E) cis-3-chloro-3-pentene

Answer 1

(E)-3-chloro-2-pentene

Question 2

What would be the name of the following compound?

A) 2,3-dimethylcyclopentene
B) (R)-1,5-dimethylcyclopentene
C) cis-2,3-dimethylcyclopentene
D) cis-1,5-dimethylcyclopentene
E) trans-2,3-dimethylcyclopentene

Answer 2

(R)-1,5-dimethylcyclopentene

Question 3

The following molecule contains how many units of unsaturation?

A) 7
B) 9
C) 10
D) 11
E) 15

Answer 3

11

Question 4

The following molecule contains how many units of unsaturation?

A) 2
B) 3
C) 5
D) 6
E) 7

Question 5

How many units of unsaturation are indicated by the following molecular formula: C₁₇H₁₈BrI₂O₂N ?

A) 0
B) 2
C) 6
D) 8
E) 10

Question 6

Infrared spectroscopy relies on what phenomenon?

A) electronic transitions
B) molecular rotations
C) nuclear alignments
D) molecular stretching and bending
E) conformational interconversion

Question 7

What functional group would be indicated by an IR absorption at 2150 cm^-1?

A) C=O
B) C=C
C) OH
D) NH
E)

Question 8

What would be the organic product of the following reaction?

A)

B)

C)

D)

E) none of the above

Question 9

What functional group would be indicated by an IR absorption at 1650 cm^-1?

A) C=O
B) C=C
C) OH
D) NH
E)

Question 10

The greatest strength of infrared spectroscopy is in determining

A) the degree of unsaturation.
B) the relationships of structural fragments.
C) the functional groups present.
D) the overall structure of the molecule.
E) if rings are present.

Question 11

The IR spectrum of a compound shows a strong absorbance peak at 1720 cm^-1.What functional group is indicated?

A) OH
B) C=C
C) NH
D) C=O
E) CN

Question 12

Under special reaction conditions, $\alpha$ -pinene and $\beta$ -pinene can be in equilibrium (caused to interconvert reversibly).Using your knowledge of alkene stability,which of the following would be true at equilibrium?

A) The $\alpha$ -isomer will predominate.
B) The $\beta$ -isomer will predominate.
C) The isomers would be equally favored.
D) A third isomer would predominate.
E) None of the above is true.

Question 13

How many degrees of unsaturation are present in the following molecule?

A) 3
B) 5
C) 7
D) 8
E) 10

Question 14

Predict the major product of the following reaction:

A)

B)

C)

D)

E) None of the above.

Question 15

Which of the following are of lowest energy?

A) radio waves
B) x-rays
C) infrared
D) ultraviolet
E) microwaves

Question 16

Which of the following most accurately describes the IR fingerprint region:

A) 2200 - 3400 cm^-1
B) 600 - 1500 cm^-1
C) 3000 - 3500 cm^-1
D) 1500 - 1850 cm^-1
E) 600 - 950 cm^-1

Question 17

Which of the following are (Z)isomers?

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

Question 18

A hydrocarbon with the molecular formula C₇H₁₂ exhibits the following spectroscopic data: ¹H NMR $\delta$ = 1.3 (m,2H),1.7 (m,4 H),2.2 (m,4H),and 4.8 (quin,J = 3 Hz,2H)ppm; ¹³C NMR: $\delta$ = 26.8,28.7,35.7,106.9,and 149.7 ppm.The IR spectrum has key absorbances at 3072,2950,and 1649 cm^-1.Hydrogenation of the compound furnishes a product with the molecular formula C₇H₁₄.Which structure is consistent with this data?

A)

B)

C)

D)

E) None of the above.

Question 19

The following molecule contains how many units of unsaturation?

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

Question 20

Which of the following alkenes of the formula C₅H₁₀ would you expect to be the least stable?

A)

B)

C)

D)

E)

Question 21

Which structure would be named 3-bromo-5-methylcyclohexene?

A)

B)

C)

D)

E) None of the above.

Question 22

Which of the following are (E)isomers?

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

Question 23

Predict the product of the following reaction:

A)

B)

C)

D)

E)

Question 24

Which of the following are of highest energy?

A) radio waves
B) X-rays
C) infrared
D) ultraviolet
E) microwaves

Question 25

A chiral compound,C₅H₈,upon simple catalytic hydrogenation yields an achiral compound.What is the best name for the former?

A) 1-methylcyclobutene
B) 3-methylcyclobutene
C) 1,2-dimethylcyclopropene
D) cyclopentene
E) None of the above.

Question 26

Which is the structure of 3,7-dimethyl-2,6-octadienal?

A)

B)

C)

D)

E)

Question 27

Choose the name of the following compound.

A) cis-4,5-dimethylcyclopentene
B) cis-1,2-dimethylcyclopent-3-ene
C) cis-2,3-dimethycyclopentene
D) cis-3,4-dimethylcyclopentene
E) cis-1,2-dimethylcyclopent-4-ene

Question 28

If you could have only one of the following to use to identify the entire structure of a previously unknown organic compound,which would be the best?

A) melting point
B) IR spectrum
C) molecular weight
D) NMR spectrum
E) boiling point

Question 29

Which is the correct order of stabilities of alkenes listed from least stable to most stable?

A)

B)

C)

D)

E)

Question 30

What product would you expect from the reaction shown below?

A)

B)

C)

D)

E)

Question 31

What is the degree of unsaturation in cyclobutene

A) zero
B) one
C) two
D) three
E) This molecule is not unsaturated.

Question 32

Based on what you know about carbon-carbon double bonds,which of the following would be true of the allene shown?

A) The two rings would be in the same plane.
B) The two rings would be in perpendicular planes.
C) There is no way to tell what geometric relationship the rings would have.
D) The three carbons shown would not be co-linear.
E) Allenes cannot exist.

Question 33

Which reagent(s)would you expect to give the highest yield of the product shown?

A) K^+-O^tBu
B) CH₃S^- Na⁺
C) H₂SO₄
D) CH₃O^- Na⁺
E) K^{+ -}CN

Question 34

A compound which shows a molecular ion at m/z 84 could plausibly have what formula?

A) C₅H₁₀N
B) C₄H₂₀O
C) C₆H₁₂
D) C₅H₂₄
E) C₅H₁₀O

Question 35

What reagent would give the highest yield of the product shown below?

A) K^+-OtBu
B) NaCN
C) CH₃S^-Na⁺
D) NaOH
E) CH₃O^-Na⁺

Question 36

Which of the following are E isomers?

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

Question 37

What would be the MAJOR organic product of the following reaction?

A)

B)

C)

D)

E)

Question 38

Which alkene would you expect to release the least amount of heat upon hydrogenation?

A)

B)

C)

D)

E)

Question 39

Which of the alkenes shown below would be expected to have the lowest melting point?

A)

B)

C)

D)

E) There is no basis for such a prediction.

Question 40

Which sets of arrows correctly represents the electron movements during an E2 reaction?

A)

B)

C)

D)

E)

Question 41

What would be the major product of the following reaction?

A)

B)

C)

D)

E)

Question 42

Enanthotoxin is an extremely poisonous organic compound found in the hemlock water dropwart,which is reputed to be the most poisonous plant in England.It is believed that no British plant has been responsible for more fatal accidents.The most poisonous part of the plant is the roots,which resemble small white carrots,giving the plant the name "five finger death." Also poisonous are its leaves,which look like parsley.Enanthotoxin is thought to interfere with the sodium ion current in nerve cells which leads to convulsions and death.How many stereoisomers are possible for enanthotoxin?

A) 2
B) 4
C) 8
D) 16
E) 32

Question 43

The mass spectrum of 1-pentanol gives a large peak at m/z = 70.This peak can be characterized as?

A) the parent ion
B) the parent ion minus hydroxide
C) the parent ion minus water
D) the parent ion plus a proton
E) None of the above.

Question 44

Label each of the alkenes as either E or Z.

A) A = E,B = Z,C = E,D = Z
B) A = Z,B = E,C = Z,D = E
C) A = Z,B = E,C = Z,D = Z
D) A = E,B = E,C = E,D = E
E) None of the above.

Question 45

The mass spectrum of isopropylbenzene gives a large peak at m/z = 105.This peak can be characterized as?

A) the parent ion
B) the parent ion minus a proton
C) the parent ion minus water
D) the parent ion minus a methyl group
E) None of the above.

Question 46

Predict the product of the following reaction.

A)

B)

C)

D)

E) no reaction

Question 47

How many degrees of unsaturation are present in the following molecule?

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