Chapter 23, Problem 23.34P

What hydrogen atoms in each compound have a $\text{p}{K}_{\text{a}}\le 25$?

a. ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CO}}_{\text{2}}{\text{CH(CH}}_{\text{3}}{\text{)}}_{\text{2}}$ c. e.

b d. f.

Interpretation Introduction

(a)

Interpretation: Hydrogen atoms with $\text{p}{K}_{\text{a}}\le 25$ in the given compound are to be identified.

Concept introduction: Acidic strength can be measured by a factor known as $\text{p}{K}_{\text{a}}$. It depends on the identity and chemical properties of the acid. Lower the value of $\text{p}{K}_{\text{a}}$, the stronger is the acid. Numerically, $\text{p}{K}_{\text{a}}$ is the negative logarithm of base $10$ of the acid dissociation constant.

Answer to Problem 23.34P

The highlighted hydrogens have ${\text{pK}}_{\text{a}}\le 25$.

Explanation of Solution

The $\text{p}{K}_{\text{a}}$ of $\alpha$ hydrogens attached to carbonyl compounds is below $25$. The negative charge of the anion formed after removing the proton is stabilized by delocalization of electrons onto the electronegative atom, that is, oxygen. The highlighted hydrogens shown in Figure 1 have $\text{p}{K}_{\text{a}}\le 25$.

Figure 1

Conclusion

The hydrogen atoms having $\text{p}{K}_{\text{a}}\le 25$ are shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: Hydrogen atoms with $\text{p}{K}_{\text{a}}\le 25$ in the compound are to be identified.

Concept introduction: Acidic strength can be measured by a factor known as $\text{p}{K}_{\text{a}}$. It depends on the identity and chemical properties of the acid. Lower the value of $\text{p}{K}_{\text{a}}$, the stronger is the acid. Numerically, $\text{p}{K}_{\text{a}}$ is the negative logarithm of base $10$ of the acid dissociation constant.

Answer to Problem 23.34P

The highlighted hydrogen atoms have ${\text{pK}}_{\text{a}}\le 25$.

Explanation of Solution

The $\text{p}{K}_{\text{a}}$ of $\alpha$ hydrogens attached to carbonyl compounds is below $25$ because the negative charge of the anion formed after removing proton is stabilized by delocalization onto the electronegative atom, that is, oxygen. The highlighted hydrogens shown in Figure 2 have $\text{p}{K}_{\text{a}}\le 25$.

Figure 2

Conclusion

The hydrogens having $\text{p}{K}_{\text{a}}\le 25$ are rightfully shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: Hydrogen atoms with $\text{p}{K}_{\text{a}}\le 25$ in the compound are to be identified.

Concept introduction: Acidic strength can be measured by a factor known as $\text{p}{K}_{\text{a}}$. It depends on the identity and chemical properties of the acid. Lower the value of $\text{p}{K}_{\text{a}}$, the stronger is the acid. Numerically, $\text{p}{K}_{\text{a}}$ is the negative logarithm of base $10$ of the acid dissociation constant.

Answer to Problem 23.34P

The highlighted hydrogen atoms have $\text{p}{K}_{\text{a}}\le 25$.

Explanation of Solution

The $\text{p}{K}_{\text{a}}$ of $\alpha$ hydrogens attached to carbonyl compounds is below $25$ because the negative charge of the anion formed after removing proton is stabilized by delocalization onto the electronegative atom i.e. oxygen. Also, alcoholic hydrogen is acidic in nature because it is attached to the electronegative atom. The highlighted hydrogens shown in Figure 3 have $\text{p}{K}_{\text{a}}\le 25$.

Figure 3

Conclusion

The hydrogens having $\text{p}{K}_{\text{a}}\le 25$ are rightfully shown in Figure 3.

Interpretation Introduction

(d)

Interpretation: Hydrogen atoms with $\text{p}{K}_{\text{a}}\le 25$ in the compound are to be identified.

Concept introduction: Acidic strength can be measured by a factor known as $\text{p}{K}_{\text{a}}$. It depends on the identity and chemical properties of the acid. Lower the value of $\text{p}{K}_{\text{a}}$, the stronger is the acid. Numerically, $\text{p}{K}_{\text{a}}$ is the negative logarithm of base $10$ of the acid dissociation constant.

Answer to Problem 23.34P

The highlighted hydrogens have $\text{p}{K}_{\text{a}}\le 25$.

Explanation of Solution

The $\text{p}{K}_{\text{a}}$ of $\alpha$ hydrogens attached to the strong electron withdrawing groups is below $25$ because the negative charge of the anion formed after removing proton is stabilized by negative inductive effect. The highlighted hydrogens shown in Figure 4 have $\text{p}{K}_{\text{a}}\le 25$.

Figure 4

Conclusion

The hydrogens having $\text{p}{K}_{\text{a}}\le 25$ are rightfully shown in Figure 4.

Interpretation Introduction

(e)

Interpretation: Hydrogen atoms with $\text{p}{K}_{\text{a}}\le 25$ in the compound are to be identified.

Concept introduction: Acidic strength can be measured by a factor known as $\text{p}{K}_{\text{a}}$. It depends on the identity and chemical properties of the acid. Lower the value of $\text{p}{K}_{\text{a}}$, the stronger is the acid. Numerically, $\text{p}{K}_{\text{a}}$ is the negative logarithm of base $10$ of the acid dissociation constant.

Answer to Problem 23.34P

The highlighted hydrogens have $\text{p}{K}_{\text{a}}\le 25$.

Explanation of Solution

The $\text{p}{K}_{\text{a}}$ of $\alpha$ hydrogens attached to carbonyl compounds is below $25$ because the negative charge of the anion formed after removing proton is stabilized by delocalization onto the electronegative atom i.e. oxygen. The highlighted hydrogens shown in Figure 5 have $\text{p}{K}_{\text{a}}\le 25$.

Figure 5

Conclusion

The hydrogens having $\text{p}{K}_{\text{a}}\le 25$ are rightfully shown in Figure 5.

Interpretation Introduction

(f)

Interpretation: Hydrogen atoms with $\text{p}{K}_{\text{a}}\le 25$ in the compound are to be identified.

Concept introduction: Acidic strength can be measured by a factor known as $\text{p}{K}_{\text{a}}$. It depends on the identity and chemical properties of the acid. Lower the value of $\text{p}{K}_{\text{a}}$, the stronger is the acid. Numerically, $\text{p}{K}_{\text{a}}$ is the negative logarithm of base $10$ of the acid dissociation constant.

Answer to Problem 23.34P

The highlighted hydrogens have $\text{p}{K}_{\text{a}}\le 25$.

Explanation of Solution

The $\text{p}{K}_{\text{a}}$ of $\alpha$ hydrogens attached to carbonyl compounds is below $25$ because the negative charge of the anion formed after removing proton is stabilized by delocalization onto the electronegative atom i.e. oxygen. Also, carboxylic hydrogen is acidic in nature because it is attached to the electronegative atom. The highlighted hydrogens shown in Figure 6 have $\text{p}{K}_{\text{a}}\le 25$.

Figure 6

Conclusion

The hydrogens having $\text{p}{K}_{\text{a}}\le 25$ are rightfully shown in Figure 6.