CHEM201-FinalExam-Answers

Benzyne is a very reactive intermediate. As a result, it is very difficult to track chemical reactions. How was its existence demonstrated?

Choose one answer.

	a. By trapping the intermediate in a cycloaddition reaction
	b. By separating it from the mixture by GC/MS
	c. By separating it from the mixture by column chromatography
	d. None of the above

Question 2

Benzyne is the mechanistic intermediate for which of the following reactions?

Choose one answer.

	a. Nucleophilic additions
	b. Electrophilic additions
	c. Cycloadditions
	d. All of the above

Question 3

Chain reactions involving free-radicals occur in which of the following orders?

Choose one answer.

	a. Initiation, propagation, termination
	b. Initiation, termination, propagation
	c. Propagation, termination, initiation
	d. Termination, propagation, initiation

Question 4

Given that the energy of a CH₃-H bond is 104 kcal/mol and that of an HO-H bond is 119 kcal/mol, what is the bond dissociation energy of the following reaction?

Choose one answer.

	a. 15 kcal/mol
	b. -15 kcal/mol
	c. 223 kcal/mol
	d. -223 kcal/mol

Question 5

Given that the energy of a CH₃bond is 104 kcal/mol, CH₃-Cl bond is 85 kcal/mol, H-Cl bond is 103 kcal/mol and that of an Cl₂ bond is 58 kcal/mol, what is the bond dissociation energy of the following reaction?

Choose one answer.

	a. 25 kcal/mol
	b. -25 kcal/mol
	c. 189 kcal/mol
	d. -166 kcal/mol

Question 6

Identify the most stable free radical.

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 7

Nitrogen ylides are very versatile and can be used in a number of chemical reactions. Which of the following is a reaction of nitrogen ylides?

Choose one answer.

	a. Cannizzaro reaction
	b. Sommelet reaction
	c. Blanc reaction
	d. Friedel-Crafts reaction

Question 8

Nitrogen ylides are very versatile and can be used in a number of chemical reactions. Which of the following reactions is NOT a reaction of nitrogen ylides?

Choose one answer.

	a. Stevens reaction
	b. Sommelet reaction
	c. Wittig reaction
	d. Friedel-Crafts reaction

Question 9

The Wittig reagent was allowed to react with and carbonyl compound with the formula C₁₀H₁₂O. The name of the product was 4-phenyl-4-octene. What is the name of the carbonyl compound used?

Choose one answer.

	a. 1-phenyl-1-butanone
	b. Acetophenone
	c. 2-phenyl-3-butanone
	d. Benzaldehyde

Question 10

What are common methods for preparing benzyne?

Choose one answer.

	a. Elimination from organolithium or organomagnesium precursors
	b. loss of neutral leaving group
	c. photolytic and/or pyrolitic methods
	d. All of the above

Question 11

What is the major product of the radical reaction of 2-methylbutane with Cl₂?

Choose one answer.

	a. 2-chloro-2-methylbutane
	b. 1-chloro-2-methylbutane
	c. 3-chloro-2-methylbutane
	d. 4-chloro-2-methylbutane

Question 12

Which halogen is most reactive in radical halogenations of alkanes?

Choose one answer.

	a. F₂
	b. Cl₂
	c. Br₂
	d. I₂

Question 13

Which of the following is NOT a method for generating free radicals?

Choose one answer.

	a. Thermal cracking
	b. Photolysis bond heterolysis
	c. Homolysis of peroxides and azo compounds
	d. Electron transfer

Question 14

Which of the following is NOT a precursor of Benzyne?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 15

Which of the following molecules is a nitrogen ylide?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 16

Which of the following molecules is a phosphorus ylide?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 17

Which of the following molecules is a sulfur ylide?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 18

Which of the following six-carbon molecules will form a single chlorinated compound when reacting with chlorine in presence of light.

Choose one answer.

	a. I
	b. II
	c. III
	d. All of them

Question 19

Which of the following Wittig reagents would be useful for converting acetophenone into 1,1-diphenylethene?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 20

Which statement about free radicals is incorrect?

Choose one answer.

	a. Free radicals contain an unpaired electron.
	b. Radicals are believed to be involved in degenerative diseases and cancers.
	c. They are formed by heterolytic cleavage of bonds.
	d. Radicals can either be neutral or ionic.

Question 21

1-chloro-3-methylhexane undergoes S_N2 reaction with sodium ethoxide. This reaction yields low amount of products. However, addition of small amounts of sodium iodide increases the rate of the reaction. Why?

Choose one answer.

	a. The charge of the sodium ion stabilizes the charge of the chloride ion.
	b. The iodide ion renders the ethoxide ion more reactive.
	c. Small amounts of alkyl chlorides are converted into the more reactive alkyl iodides.
	d. With the presence of N_aI, the mechanism changes to S_n1.

Question 22

Compound A undergoes a rearrangement reaction and forms compounds B and C. Based on the potential energy diagram below, what can be said about compounds B and C in terms of kinetics and thermodynamics?

Choose one answer.

	a. B is the kinetic and thermodynamic product.
	b. B is the kinetic product, and C is the thermodynamic product.
	c. C is the kinetic product, and B is the thermodynamic product.
	d. C is the kinetic and thermodynamic product.

Question 23

Provide the IUPAC name, including stereochemical designation, for the following molecule.

Choose one answer.

	a. (2R,3R)-2,3-dibromopentane
	b. (2S,3S)-2,3-dibromopentane
	c. (2R,3S)-2,3-dibromopentane
	d. (2S,3R)-2,3-dibromopentane

Question 24

Select the mechanism by which the reactants below will react.

Choose one answer.

	a. S_N1
	b. S_N2
	c. E1
	d. E2

Question 25

Vinyl chloride, shown below, does not react with sodium hydroxide in S_N2 reactions. Why?

Choose one answer.

	a. Hydroxide is a weak nucleophile.
	b. The sp2 carbon-chlorine bond is stronger than the sp3 carbon-chlorine bond.
	c. The chlorine atom is sterically crowded.
	d. Both B and C

Question 26

What is the configuration at the carbons labeled 1 and 2 in the following compound?

Choose one answer.

	a. 1R, 2S
	b. 1S, 2R
	c. 1R, 2R
	d. 1S, 2S

Question 27

What is the major product of the following reaction?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 28

What is the relationship between the two compounds below?

Choose one answer.

	a. Same compound
	b. Structural isomers
	c. Enantiomers
	d. Diastereomers

Question 29

What reaction will the following compound most likely undergo?

Choose one answer.

	a. SN1
	b. SN2
	c. E1
	d. E2

Question 30

Which is the correct structural formula for the compound formed according to the mechanism below (lone electron pairs were omitted)?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 31

Which of the following alkyl halides give only one alkene as the product in the E2 reaction?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 32

Which of the following carbocations is most stable?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 33

Which of the following compound h as the IUPAC name of (2R, 3R)-2, 3-dihydroxybutane?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 34

Which of the following compounds is chiral?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 35

Which of the following compounds will be the most reactive substrate in S_N1 reactions?

Choose one answer.

	a. (C₂H₅)₃CCl
	b. (C₂H₅)₂CHCl
	c. C₂H₅CH₂Cl
	d. (C₂H₅)₃CF

Question 36

Which of the following compounds will most readily react in S¬N1 reactions?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 37

Which of the following molecules is prochiral?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 38

Which of the following statements about chirality is incorrect?

Choose one answer.

	a. A chiral center is an atom that is tetrahedrally bonded to four different groups.
	b. A chiral molecule has a superimposable mirror image.
	c. A chiral molecule does not have any reflective symmetry.
	d. All chiral molecules may exist as enantiomers.

Question 39

Which of the following statements about the chemical reaction described below is true?

Choose one answer.

	a. The product will have R configuration.
	b. The product will have S configuration.
	c. The product will be achiral.
	d. The product will be a racemic mixture.

Question 40

Which of the following statements best describes an E2 reaction?

Choose one answer.

	a. It involves a two-step mechanism.
	b. It involves a very reactive intermediate.
	c. The rate of the reaction depends on the concentration of the base.
	d. The rate of the reaction increases in polar solvents.

Question 41

Name the following compound.

Choose one answer.

	a. Phenylmagnesium bromide
	b. Ethylphenylmagnesium bromide
	c. Benzylmagnesium bromide
	d. Benzylicmagnesium bromide

Question 42

The Grignard reaction is an important reaction to provide which of the following?

Choose one answer.

	a. Carbon-carbon bonds
	b. Carbon-magnesium bonds
	c. Carbon-halide bonds
	d. Magnesium-halide bonds

Question 43

What happens to the chiral center when (R)-3-methyl-3-phenyl-4-heptanone reacts with phenylmagnesium bromide?

Choose one answer.

	a. Inversion of configuration occurs.
	b. A racemic mixture is formed.
	c. Nothing, the chiral center remains unchanged.
	d. The product is achiral.

Question 44

What is organometallic chemistry?

Choose one answer.

	a. The study of carbon containing compounds
	b. The study of compounds containing a carbon-metal bond
	c. The study of metals
	d. The study of salts

Question 45

What is the chemical structure of furan?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 46

What is the IUPAC name for the imidazole molecule, shown below?

Choose one answer.

	a. Imidazole
	b. 1,3-imidazole
	c. Diazole
	d. 1,3-diazole

Question 47

What is the major product of the following reaction?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 48

What is the major product of the following reaction?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 49

What is the name of the following heterocycle?

Choose one answer.

	a. Isoquinoline
	b. Indole
	c. Quinoline
	d. Pyrrolidine

Question 50

What is the name of the following heterocycle?

Choose one answer.

	a. Isoquinoline
	b. Indole
	c. Quinoline
	d. Pyrrolidine

Question 51

What is the name of the following heterocycle?

Choose one answer.

	a. Thiazole
	b. Indole
	c. Quinoline
	d. Pyrrolidine

Question 52

Which of the following alkyl halides would be suitable to use when forming a Grignard reagent?

Choose one answer.

	a. CH₃CH₂CH(OH)CH₂Br
	b. BrCH2CO2H
	c. PhCH2CH2Br
	d. None of these are suitable

Question 53

Which of the following heterocycles is most basic?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 54

Which of the following is an organometallic compound?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 55

Which of the following molecules is an heterocycle?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 56

Which of the following molecules will NOT be a product of the following reaction?

Choose one answer.

	a. I
	b. II
	c. III
	d. All of the above

Question 57

Which of the following reactions would be a useful way of preparing 1-phenyl-1-butanol?

Choose one answer.

	a. Butanal and phenylmagnesium bromide
	b. 1-phenyl-3-butanone and NaBH4
	c. Propanal and benzylmagnesium bromide
	d. Both A and C

Question 58

Which of the heterocyclic compounds shown below is most acidic?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 59

Which of the heterocyclic compounds shown below is most basic?

Choose one answer.

	a. I
	b. II
	c. III
	d. IV

Question 60

Which reagent is best for the reaction below?

Choose one answer.

	a. I
	b. II
	c. III
	d. None of the above