Organic Chemistry
Organic Chemistry
2nd Edition
ISBN: 9781118452288
Author: David R. Klein
Publisher: WILEY
Question
Chapter 22, Problem 57PP

(a)

Interpretation Introduction

Interpretation:

To identify which of the given set of compounds have pKa value lesser than 20 and to identify the acidic proton in the same

Concept introduction:

pKa is negative base-10 logarithm of the dissociation constant of acid (Ka) of a solution. pKa= -log10Ka pKa value of acid is inversely related to the strength of acid.  If pKa value is lower it means the acid is stronger and vice-versa.

pKa is used is to describe acid dissociation because it is expressed in small decimal numbers.

If pKa value is below 20 the compound is said to have acidic proton and vice versa

To identify : The compound pKa value and the most acidic proton

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  1

(a)

Expert Solution
Check Mark

Answer to Problem 57PP

The pKa value of (a) is just below 20 and it has acidic proton next to carbonyl

Explanation of Solution

Deprotonation of the highlighted hydrogen and resonance stabilization

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  2

 From the above scheme we can infer that the highlighted hydrogen is removed resulting in formation of a conjugate base.  The conjugate base is resonance stabilized as the negative charge is delocalized on oxygen atom also.  Therefore the highlighted proton is most acidic (pKa value below 20) as the removal of it leads to a stabilized conjugate base.

(b)

Interpretation Introduction

Interpretation:

To identify which of the given set of compounds have pKa value lesser than 20 and to identify the acidic proton in the same

Concept introduction:

pKa is negative base-10 logarithm of the dissociation constant of acid (Ka) of a solution. pKa= -log10Ka pKa value of acid is inversely related to the strength of acid.  If pKa value is lower it means the acid is stronger and vice-versa.

pKa is used is to describe acid dissociation because it is expressed in small decimal numbers.

If pKa value is below 20 the compound is said to have acidic proton and vice versa

To identify : The compound pKa value and the most acidic proton

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  3

(b)

Expert Solution
Check Mark

Answer to Problem 57PP

The pKa value of (b) is just above 20 and it does not have acidic proton

No acidic proton is present

Explanation of Solution

The above given compound does not have an acidic proton that can undergo deprotonation.  Hence this compound is expected to have pKa above 20.

(c)

Interpretation Introduction

Interpretation:

To identify which of the given set of compounds have pKa value lesser than 20 and to identify the acidic proton in the same

Concept introduction:

pKa is negative base-10 logarithm of the dissociation constant of acid (Ka) of a solution. pKa= -log10Ka pKa value of acid is inversely related to the strength of acid.  If pKa value is lower it means the acid is stronger and vice-versa.

pKa is used is to describe acid dissociation because it is expressed in small decimal numbers.

If pKa value is below 20 the compound is said to have acidic proton and vice versa

To identify : The compound pKa value and the most acidic proton

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  4

(c)

Expert Solution
Check Mark

Answer to Problem 57PP

The pKa value of (c) is just below 20 and it has acidic proton next to carbonyl

Explanation of Solution

Deprotonation of the highlighted hydrogen and resonance stabilization

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  5

From the above scheme we can infer that the highlighted hydrogen is removed resulting in formation of a conjugate base.  The conjugate base is resonance stabilized as the negative charge is delocalized on oxygen atom also.  Therefore the highlighted proton is most acidic (pKa value below 20) as the removal of it leads to a stabilized conjugate base.

(d)

Interpretation Introduction

Interpretation:

To identify which of the given set of compounds have pKa value lesser than 20 and to identify the acidic proton in the same

Concept introduction:

pKa is negative base-10 logarithm of the dissociation constant of acid (Ka) of a solution. pKa= -log10Ka pKa value of acid is inversely related to the strength of acid.  If pKa value is lower it means the acid is stronger and vice-versa.

pKa is used is to describe acid dissociation because it is expressed in small decimal numbers.

If pKa value is below 20 the compound is said to have acidic proton and vice versa

To identify : The compound pKa value and the most acidic proton

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  6

(d)

Expert Solution
Check Mark

Answer to Problem 57PP

The pKa value of (d) is just below 20 and it has acidic proton next to carbonyl

Explanation of Solution

Deprotonation of the highlighted hydrogen and resonance stabilization

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  7

From the above scheme we can infer that the highlighted hydrogen is removed resulting in formation of a conjugate base.  The conjugate base is resonance stabilized as the negative charge is delocalized on two oxygen atoms (doubly stabilized enolate ion).  Therefore the highlighted proton is most acidic (pKa value below 20) as the removal of it leads to a stabilized conjugate base.

(e)

Interpretation Introduction

Interpretation:

To identify which of the given set of compounds have pKa value lesser than 20 and to identify the acidic proton in the same

Concept introduction:

pKa is negative base-10 logarithm of the dissociation constant of acid (Ka) of a solution. pKa= -log10Ka pKa value of acid is inversely related to the strength of acid.  If pKa value is lower it means the acid is stronger and vice-versa.

pKa is used is to describe acid dissociation because it is expressed in small decimal numbers.

If pKa value is below 20 the compound is said to have acidic proton and vice versa

To identify : The compound pKa value and the most acidic proton

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  8

(e)

Expert Solution
Check Mark

Answer to Problem 57PP

The pKa value of (e) is just below 20 and it has acidic proton next to carbonyl

Explanation of Solution

Deprotonation of the highlighted hydrogen

Organic Chemistry, Chapter 22, Problem 57PP , additional homework tip  9

From the above scheme we can infer that the highlighted hydrogen is removed resulting in formation of an alokoxide ion.  As such the compound is expected to have pKa lower than 20.

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Chapter 22 Solutions

Organic Chemistry

Ch. 22.2 - Prob. 10CCCh. 22.2 - Prob. 11CCCh. 22.2 - Prob. 12CCCh. 22.2 - Prob. 13CCCh. 22.2 - Prob. 14CCCh. 22.3 - Prob. 2LTSCh. 22.3 - Prob. 15PTSCh. 22.3 - Prob. 16PTSCh. 22.3 - Prob. 17ATSCh. 22.3 - Prob. 18ATSCh. 22.3 - Prob. 19ATSCh. 22.3 - Prob. 3LTSCh. 22.3 - Prob. 20PTSCh. 22.3 - Prob. 21ATSCh. 22.3 - Prob. 22ATSCh. 22.3 - Prob. 4LTSCh. 22.3 - Prob. 23PTSCh. 22.3 - Prob. 24ATSCh. 22.3 - Prob. 25CCCh. 22.3 - Prob. 26CCCh. 22.3 - Prob. 27CCCh. 22.4 - Prob. 28CCCh. 22.4 - Prob. 29CCCh. 22.4 - Prob. 30CCCh. 22.4 - Prob. 31CCCh. 22.4 - Prob. 32CCCh. 22.5 - Prob. 33CCCh. 22.5 - Prob. 34CCCh. 22.5 - Prob. 5LTSCh. 22.5 - Prob. 35PTSCh. 22.5 - Prob. 36ATSCh. 22.5 - Prob. 37ATSCh. 22.5 - Prob. 38ATSCh. 22.5 - Prob. 6LTSCh. 22.5 - Prob. 39PTSCh. 22.5 - Prob. 40ATSCh. 22.5 - Prob. 41ATSCh. 22.5 - Prob. 42ATSCh. 22.5 - Prob. 43ATSCh. 22.6 - Prob. 44CCCh. 22.6 - Prob. 45CCCh. 22.6 - Prob. 46CCCh. 22.6 - Prob. 7LTSCh. 22.6 - Prob. 47PTSCh. 22.6 - Prob. 48ATSCh. 22.6 - Prob. 49CCCh. 22.6 - Prob. 50CCCh. 22.7 - Prob. 8LTSCh. 22.7 - Prob. 51PTSCh. 22.7 - Prob. 52PTSCh. 22.7 - Prob. 53ATSCh. 22.7 - Prob. 9LTSCh. 22.7 - Prob. 54PTSCh. 22.7 - Prob. 55ATSCh. 22.7 - Prob. 56ATSCh. 22 - Prob. 57PPCh. 22 - Prob. 58PPCh. 22 - Prob. 59PPCh. 22 - Prob. 60PPCh. 22 - Prob. 61PPCh. 22 - Prob. 62PPCh. 22 - Prob. 63PPCh. 22 - Prob. 64PPCh. 22 - Prob. 65PPCh. 22 - Prob. 66PPCh. 22 - Prob. 67PPCh. 22 - Prob. 68PPCh. 22 - Prob. 69PPCh. 22 - Prob. 70PPCh. 22 - Prob. 71PPCh. 22 - Prob. 72PPCh. 22 - Prob. 73PPCh. 22 - Prob. 74PPCh. 22 - Prob. 75PPCh. 22 - Prob. 76PPCh. 22 - Prob. 77PPCh. 22 - Prob. 78PPCh. 22 - Prob. 79PPCh. 22 - Prob. 80PPCh. 22 - Prob. 81PPCh. 22 - Prob. 82PPCh. 22 - Prob. 83PPCh. 22 - Prob. 84PPCh. 22 - Prob. 85PPCh. 22 - Prob. 86PPCh. 22 - Prob. 87PPCh. 22 - Prob. 88PPCh. 22 - Prob. 89PPCh. 22 - Prob. 90PPCh. 22 - Prob. 91PPCh. 22 - Prob. 92PPCh. 22 - Prob. 93PPCh. 22 - Prob. 94PPCh. 22 - Prob. 95PPCh. 22 - Prob. 96PPCh. 22 - Prob. 97PPCh. 22 - Prob. 98PPCh. 22 - Prob. 99PPCh. 22 - Prob. 100IPCh. 22 - Prob. 101IPCh. 22 - Prob. 102IPCh. 22 - Prob. 103IPCh. 22 - Prob. 104IPCh. 22 - Prob. 105IPCh. 22 - Prob. 106IPCh. 22 - Prob. 107IPCh. 22 - Prob. 108IPCh. 22 - Prob. 109IPCh. 22 - Prob. 110IPCh. 22 - Prob. 111IPCh. 22 - Prob. 112IP
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