Practice Problems by Chapter

OChem2 Homework

Practice Problems by Chapter

Dr. Peter Norris OChem 2

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Klein Chapter 13 Problems : Alcohols and Phenols

1. Provide each of the following molecules with an acceptable name. You may use IUPAC or “common” names for substituents. Be sure to include any stereochemical descriptors where needed (R/S, cis/trans).

2. Give the (major and minor) product(s) expected to be formed from each step under each of the following sets of reaction conditions. Include any stereochemical issues that might be important in each outcome.

3. Provide detailed mechanisms for each of the following conversions that include all important resonance structures for any intermediates that are formed. Include any stereochemical changes that might take place.

4. Rank the following molecules in terms of their increasing acid strength; 1 = weakest acid, 4 = strongest acid. Give brief explanations for your choices.


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Klein Chapter 13 Problems : Alcohols and Phenols - Answers

1. “Provide each of the following molecules with an acceptable name. You may use IUPAC or “common” names for substituents. Be sure to include any stereochemical descriptors where needed (R/S, cis/trans).”

2. “Give the (major and minor) product(s) expected to be formed from each step under each of the following sets of reaction conditions. Include any stereochemical issues that might be important in each outcome.”

3. “Provide detailed mechanisms for the following conversions that include all important resonance structures for any intermediates that are formed. Include any stereochemical changes that might take place.”


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4. “Rank the following molecules in terms of their increasing acid strength; 1 = weakest acid, 4 = strongest acid. Give brief explanations for your choices.”

1 is a simple alcohol in which the conjugate base will have the negative charge localized on O; 2 is an enol so the conjugate

base charge will be stabilized by resonance; 3 is a phenol so the conjugate base is stabilized significantly by delocalization

into the phenyl ring; 4 is a phenol with a strongly electron-withdrawing NO2 group that stabilizes better than CH3 in 3.


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Klein Chapter 14 Problems : Ethers & Epoxides ; Thiols & Sulfides

1. Provide each of the following ethers with an acceptable name. You may use IUPAC or “common” names for substituents. Be sure to include any stereochemical descriptors where needed (R/S, cis/trans).

2. Give the (major and minor) product(s) expected to be formed from each step under each of the following sets of reaction conditions. Include any stereochemical issues that might be important in each outcome.

3. Provide detailed mechanisms for each of the following conversions that include all important resonance structures for any intermediates that are formed. Include any stereochemical changes that might take place.

4. Provide viable, efficient syntheses of the products shown from the starting materials provided in each case. You may use any of the chemistry and reagents seen so far in Organic 1 and Organic 2.


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Klein Chapter 14 Problems : Ethers & Epoxides ; Thiols & Sulfides - Key

1. “Provide each of the following ethers with an acceptable name. You may use IUPAC or “common” names for substituents. Be sure to include any stereochemical descriptors where needed (R/S, cis/trans).”

2. “Give the (major and minor) product(s) expected to be formed from each step under each of the following sets of reaction conditions. Include any stereochemical issues that might be important in each outcome.”

3. “Provide detailed mechanisms for the following conversions that include all important resonance structures for any intermediates that are formed. Include any stereochemical changes that might take place.”


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4. “Provide viable, efficient syntheses of the products shown from the starting materials provided in each case. You may use any of the chemistry and reagents seen so far in Organic 1 and Organic 2.”


1

Klein Chapter 15 Problems : IR Spectroscopy & MS Spectrometry

1. In each of the following situations, which one of the molecules matches the given IR spectrum? Match as many frequencies as you can from the spectroscopy sheet to back up your answers.

a)

b)

c)


2

2. In each of the following situations, which one of the molecules matches the given mass spectrum? Match as many fragments as you can to back up your answers.

a)

b)

c)


3

3. A pharmaceutical compound has the formula C9H8O4 and the following IR and mass spectral characteristics. The pKa of the most acidic proton on the compound was found to be ~5. Calculate the degrees of unsaturation present in the molecule and then suggest a structure that agrees with the data given.

Important IR signals: 3100, 3000, 2850, 1740, 1700, 1620, 1300, 1175, 900, 750 cm-1.

Important MS signals: m/z 180, 162, 138, 122, 121, 94, 44.


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Klein Chapter 15 Problems : IR Spectroscopy & MS Spectrometry - Key

1. In each of the following situations, which one of the molecules matches the given IR spectrum? Match as many frequencies as you can from the spectroscopy sheet to back up your answers.

a)

b)

c)


2

2. In each of the following situations, which one of the molecules matches the given mass spectrum? Match as many fragments as you can to back up your answers.

a)

b)

c)


3

3. A pharmaceutical compound has the formula C9H8O4 and the following IR and mass spectral characteristics. The pKa of the most acidic proton on the compound was found to be ~5. Calculate the degrees of unsaturation present in the molecule and then suggest a structure that agrees with the data given.

Degrees of Unsaturation = [#C – (#H/2) – (#X/2) + (#N/2)] + 1

9-4+1 = 6 cycles or multiple bonds (benzene ring = 4; C=O = 2)

Important IR signals: 3100 (OH), 3000 (C-H), 2850 (C-H), 1740 (C=O), 1700 (C=O), 1620 (C=C), 1300 (C-O), 1175 (C-O), 900, 750 (m-disubstituted) cm-1.

Important MS signals: m/z 180 (M+), 162 (M-OH), 138 (M-CH3CO), 122 (M-CH3CO2H), 121 (M-CH3CO2), 94 (PhOH), 44 (CH3CO).


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Klein Chapter 16 Problems : Nuclear Magnetic Resonance Spectroscopy

1. In each of the following situations, which one of the molecules matches the given 1H NMR spectrum? Match as many signals as you can from the spectroscopy sheet to back up your answers.

a)

b)


2

c)

d)

2. How many individual signals do you expect to appear in the 13C spectra of each of the following?


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3. In each of the following situations, which one of the molecules matches the given 13C NMR spectrum? Match as many signals as you can from the spectroscopy sheet to back up your answers.

a)

b)


4

c)

d)


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Klein Chapter 16 Problems : NMR Spectroscopy – Answers

1. In each of the following situations, which one of the molecules matches the given 1H NMR spectrum? Match as many signals as you can from the spectroscopy sheet to back up your answers.

a)

b)


2

c)

d)

2. How many individual signals do you expect to appear in the 13C spectra of each of the following?


3

3. In each of the following situations, which one of the molecules matches the given 13C NMR spectrum? Match as many signals as you can from the spectroscopy sheet to back up your answers.

a)

b)


4

c)

d)


1

Klein Chapter 17 Problems : Conjugated Pi Systems & Pericyclic Reactions

1. For each of the following reactions, decide which product is major and which is minor and then provide a mechanistic rationale for your choices that includes arrow pushing and discussions of any intermediate structure or stereochemical factors necessary.

2. In each of the following instances, provide the major and minor products (where applicable) that you expect to be formed under the conditions provided.

3. Within each pair of molecules below, which one do you expect to absorb at the longer wavelength in UV-

Visible spectroscopy? Briefly explain your choices.


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Klein Chapter 17 Problems : Conjugated Pi Systems - Answers

1. For each of the following reactions, decide which product is major and which is minor and then provide a mechanistic rationale for your choices that includes arrow pushing and discussions of any intermediate structure or stereochemical factors necessary.


2

2. In each of the following instances, provide the major and minor products (where applicable) that you expect to be formed under the conditions provided.

3. Within each pair of molecules below, which one do you expect to absorb at the longer wavelength in UV-

Visible spectroscopy? Briefly explain your choices.


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Klein Chapter 18 Problems : Aromatic Compounds

1. Provide each of the following benzene derivatives with an acceptable name.

2. Using Huckel’s rule, indicate which of the following molecules are expected to be aromatic and which are not.

3. Provide the major products that you expect to be formed under each of the following sets of reaction

conditions.


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Klein Chapter 18 Problems : Aromatic Compounds - Answers

1. “Provide each of the following benzene derivatives with an acceptable name.”

2. “Using Huckel’s rule, indicate which of the following molecules are expected to be aromatic and which are not.”


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3. “Provide the major products that you expect to be formed under each of the following sets of reaction

conditions.”


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Klein Chapter 19 Problems : Electrophilic Aromatic Substitution

1. Give the expected major products from each step of the following reaction sequences. Assume that you are able to separate isomers when needed.

2. Provide reagents that would allow for each of the following transformations to be successful. Assume that you are able to separate isomers when needed.


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Klein Chapter 19 Problems : EAS - Answers

1. Give the expected major products from each step of the following reaction sequences. Assume that you are able to separate isomers when needed.


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2. Provide reagents that would allow for each of the following transformations to be successful. Assume that you are able to separate isomers when needed.


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Klein Chapter 20 Problems : Aldehydes and Ketones

1. Give the expected major products from each step of the following reaction sequences.

2. Give retrosynthetic analyses for the following molecules that go back to the given starting materials, and then

provide the synthesis in the forward direction. Assume you have access to the usual other reagents (HBr, HNO3, NaBH4, etc.) in the lab.


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Klein Chapter 20 Problems : Aldehydes and Ketones - Answers

1. Give the expected major products from each step of the following reaction sequences.


2

2. Give retrosynthetic analyses for the following molecules that go back to the given starting materials, and then provide the synthesis in the forward direction. Assume you have access to the usual other reagents (HBr, HNO3, NaBH4, etc.) in the lab.


3

Synthesis


4

Synthesis


5

Synthesis


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Klein Chapter 21 Problems : Carboxylic Acids & Derivatives

1. Give retrosynthetic analyses for the following molecules that go back to the given starting materials, and then provide the synthesis in the forward direction. Assume you have access to the usual other reagents (HBr, HNO3, NaBH4, etc.) in the lab.

2. In the boxes provided, give the products from each step in the following “road-map” scheme. Predict the 1H NMR spectra of each of the organic products from each step.


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Klein Chapter 21 Problems : Carboxylic Acids & Derivs. – Answers

1. Give retrosynthetic analyses for the following molecules that go back to the given starting materials, and then provide the synthesis in the forward direction. Assume you have access to the usual other reagents (HBr, HNO3, NaBH4, etc.) in the lab. a.


2

b.

c.


3

d.


4

2. In the boxes provided, give the products from each step in the following “road-map” scheme. Predict the 1H NMR spectra of each of the organic products from each step.

7.26

7.19

7.26

7.66

7.66MgBr

02468PPM

7.18

7.22

7.18

7.44

7.44Br

02468PPM

7.66

7.79

7.66

8.21

8.21

O

OMgBr

02468PPM

7.66

7.79

7.66

8.21

8.21

12.74

O

OH

024681012PPM


5

7.56

7.66

7.56

8.05

8.05 3.89O

O

02468PPM

7.82

8.47 8.60

8.44 3.89

N+

O O-

O

O

02468PPM

7.64

8.19 8.25

7.93

1.30

1.30

OLi

N+

O O-

02468PPM

7.64

8.19 8.25

7.93

5.52

1.30

1.30

OH

N+

O O-

02468PPM


1

Klein Chapter 22 Problems : Enols and Enolates

1. Give the major organic product(s) from each step of the following synthetic sequence.

2. In the boxes provided, give the products from each step in the following “road-map” scheme.


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3. The polyether compound chauncydermolide G (shown below) was recently isolated by Triplet Pharmaceuticals Inc. and found to have promising antibiotic properties. In order to prove the structure unequivocally, a total synthesis beginning with the shown starting material was carried out. Give structures for each of the products in the synthetic sequence.


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Klein Chapter 22 Problems : Enols and Enolates – Answers


2. In the boxes provided, give the products from each step in the following “road-map” scheme.


2

3. The polyether compound chauncydermolide G (shown below) was recently isolated by Triplet Pharmaceuticals Inc. and found to have promising antibiotic properties. In order to prove the structure unequivocally, a total synthesis beginning with the shown starting material was carried out. Give structures for each of the products in the synthetic sequence.


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Klein Chapter 23 Problems : Amines


2. Provide the major product from each step of the following reaction sequences.



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Klein Chapter 23 Problems : Amines - Answers




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