Question 1

The [2+2] cycloaddition reaction of ethylene to form cyclobutane does not occur because _____. ​

Accepted Answer

A)  the reaction is forbidden as determined by the frontier molecular orbital analysis 
B)  the reaction is allowed as determined by the frontier molecular orbital analysis 
C)  the reaction is allowed, and ethylene collides in a suprafacial manner 
D)  the reaction is allowed, and ethylene collides in an antarafacial manner 
A)  the reaction is forbidden as determined by the frontier molecular orbital analysis 
B)  the reaction is allowed as determined by the frontier molecular orbital analysis 
C)  the reaction is allowed, and ethylene collides in a suprafacial manner 
D)  the reaction is allowed, and ethylene collides in an antarafacial manner

Question 2

Consider the following reaction.   This is an example of a sigmatropic reaction with a [3,3]-shift.

Accepted Answer

A) True 
 B)False

Question 3

What is (are) the major organic product(s) formed in the following reaction?

Accepted Answer

A)  only 1 
B)  only 1 and 3 
C)  only 2 and 4 
D)  only 1 and 4 
A)  only 1 
B)  only 1 and 3 
C)  only 2 and 4 
D)  only 1 and 4

Question 4

What is the reactive intermediate in the reaction of 1,3-butadiene with HBr resulting in 1,2-addition?

Accepted Answer

A)  cyclic bromonium cation 
B)  allylic cation 
C)  allylic radical 
D)  dienophile 
A)  cyclic bromonium cation 
B)  allylic cation 
C)  allylic radical 
D)  dienophile

Question 5

When an organic molecule is irradiated with ultraviolet radiation, the energy absorbed by the molecule corresponds to the amount necessary to excite electrons from one molecular orbital to another.

Accepted Answer

A) True 
 B)False

Question 6

What is the kinetic product obtained from the addition of 1 mole of bromine to 1,3-butadiene?

Accepted Answer

A)  3,4-dibromo-1-butene 
B)  (
E) -1,4-dibromo-2-butene 
C)  (Z)-1,4-dibromo-2-butene 
D)  (Z)-2,3-dibromo-2-butene 
A)  3,4-dibromo-1-butene 
B)  (
E) -1,4-dibromo-2-butene 
C)  (Z)-1,4-dibromo-2-butene 
D)  (Z)-2,3-dibromo-2-butene

Question 7

Draw two resonance structures of the reactive intermediate that accounts for the formation of 1,2- and 1,4-addition products upon reaction of 1,3-butadiene with one equivalent of bromine.

Accepted Answer

The answer of Draw two resonance structures of the reactive...

Question 8

Consider the reaction below to answer the following question(s):   Enter the appropriate letter in the blank for each the following statements.
-The product that results from following mechanistic step is _____.

Accepted Answer

The answer of Consider the reaction below to answer the...

Question 9

What is the major organic product obtained from the following reaction?

Accepted Answer

The answer of What is the major organic product obtained...

Question 10

Which of the following has the highest value of λmax in the ultraviolet-visible spectrum?

Accepted Answer

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

Question 11

The molar absorptivity of ethylene in hexane is 15,000 L mol−1 cm−1. What is the maximum absorbance observed at a concentration of 1.5 x 10−4 mol L−1? (Path length = 1 cm)

Accepted Answer

A)  2.25 
B)  1.25 
C)  3.25 
D)  2.52 
A)  2.25 
B)  1.25 
C)  3.25 
D)  2.52

Question 12

Which of the following relationships is not valid as applied to ultraviolet-visible spectroscopy?

Accepted Answer

A)  A = log (Io/I) 
B)  A = εcl 
C)  ΔE = hν 
D)  A = λmaxl 
A)  A = log (Io/I) 
B)  A = εcl 
C)  ΔE = hν 
D)  A = λmaxl

Question 13

What quantity is abbreviated as ε in ultraviolet-visible spectroscopy?

Accepted Answer

A)  absorbance 
B)  molecular absorptivity 
C)  intensity of transmitted light 
D)  wavelength of maximum absorbance 
A)  absorbance 
B)  molecular absorptivity 
C)  intensity of transmitted light 
D)  wavelength of maximum absorbance

Question 14

Consider the reaction below to answer the following question(s):   Enter the appropriate letter in the blank for each the following statements.
-The nucleophile in this reaction is ____.

Accepted Answer

The answer of Consider the reaction below to answer the...

Question 15

Which of the following energy diagrams represents the electronic state of butadiene after absorption of radiation?

Accepted Answer

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

Exam 20: Dienes, Conjugated Systems, and Pericyclic Reactions

The [2+2] cycloaddition reaction of ethylene to form cyclobutane does not occur because _____. ​

Consider the following reaction. This is an example of a sigmatropic reaction with a [3,3]-shift.

What is (are) the major organic product(s) formed in the following reaction?

What is the reactive intermediate in the reaction of 1,3-butadiene with HBr resulting in 1,2-addition?

When an organic molecule is irradiated with ultraviolet radiation, the energy absorbed by the molecule corresponds to the amount necessary to excite electrons from one molecular orbital to another.

What is the kinetic product obtained from the addition of 1 mole of bromine to 1,3-butadiene?

Draw two resonance structures of the reactive intermediate that accounts for the formation of 1,2- and 1,4-addition products upon reaction of 1,3-butadiene with one equivalent of bromine.

Consider the reaction below to answer the following question(s): Enter the appropriate letter in the blank for each the following statements. -The product that results from following mechanistic step is _____.

What is the major organic product obtained from the following reaction?

Which of the following has the highest value of λmax in the ultraviolet-visible spectrum?

The molar absorptivity of ethylene in hexane is 15,000 L mol−1 cm−1. What is the maximum absorbance observed at a concentration of 1.5 x 10−4 mol L−1? (Path length = 1 cm)

Which of the following relationships is not valid as applied to ultraviolet-visible spectroscopy?

What quantity is abbreviated as ε in ultraviolet-visible spectroscopy?

Consider the reaction below to answer the following question(s): Enter the appropriate letter in the blank for each the following statements. -The nucleophile in this reaction is ____.

Which of the following energy diagrams represents the electronic state of butadiene after absorption of radiation?

Covalent Bonding and Shapes of Molecules

Alkanes and Cycloalkanes

Stereoisomerism and Chirality

Acids and Bases

Alkenes: Bonding, Nomenclature, and Properties

Reactions of Alkenes

Alkynes

Haloalkanes, Halogenation, and Radical Reactions

Nucleophilic Substitution and Beta-Elimination

Alcohols

Ethers, Epoxides, and Sulfides

Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Mass Spectrometry

An Introduction to Organometallic Compounds

Aldehydes and Ketones

Carboxylic Acids

Functional Derivatives of Carboxylic Acids

Enolate Anions and Enamines

Benzene and the Concept of Aromaticity

Reactions of Benzene and Its Derivatives

Amines

Catalytic Carbon-Carbon Bond Formation

Carbohydrates

Lipids

Amino Acids and Proteins

Nucleic Acids

Organic Polymer Chemistry

Filters

The [2+2] cycloaddition reaction of ethylene to form cyclobutane does not occur because _____.

Which of the following has the highest value of λ_max in the ultraviolet-visible spectrum?

The molar absorptivity of ethylene in hexane is 15,000 L mol⁻¹ cm⁻¹. What is the maximum absorbance observed at a concentration of 1.5 x 10⁻⁴ mol L⁻¹? (Path length = 1 cm)