Chapter 2, Problem 2.11P

Interpretation Introduction

Interpretation:

The functional groups in table 1-6 that possess at least one $\text{H}$- bond acceptor but no $\text{H}$- bond donors, at least one $\text{H}$- bond donor and $\text{H}$- bond acceptor, and no $\text{H}$- bond donors and no $\text{H}$- bond acceptors are to be given.

Concept introduction:

An $\text{H}$- bond donor is an $\text{H}$ atom that is covalently bonded to a strongly electronegative atom such as $\text{N, O or F}$ and the $\text{H}$- bond acceptor is the neighboring electronegative ion or molecule which must possess a lone pair of electrons.

Answer to Problem 2.11P

(A) The names of the functional groups from the given table that possess at least one $\text{H}$- bond acceptor but no H-bond donors are: Nitrile, Ether, Ketone, Acetal, Aldehyde, Alkyl halide (Only if X = F), Epoxide, Ester, Amine and Amide.

(B) The names of the functional groups from the given table which possess at least one $\text{H}$- bond donor and one $\text{H}$- bond acceptor are: Hemiacetal, Carboxylic acid, Alcohol, and Phenol.

(C) The functional groups from the given table which possess no H-bond donors and no $\text{H}$- bond acceptors are Alkene, Thiol, Alkyne, Arene or aromatic compound, Alkyl halide (Only if X = Cl, Br, I).

Explanation of Solution

(A) The functional groups from the given table which possess at least one $\text{H}$- bond acceptor but no $\text{H}$- bond donors are:

1. The given functional group is Nitrile:

In this functional group, due to the high electronegativity of the N atom with a lone pair of electrons, there is one H-bond acceptor.

2) The given functional group is Ether:

In this functional group, due to the high electronegativity of the O atom with a lone pair of electrons, there is one H-bond acceptor.

3) The given functional group is Ketone:

In this functional group, due to the high electronegativity of the O atom with a lone pair of electrons, there is one H-bond acceptor.

4) The given functional group is Acetal:

In this functional group, due to the high electronegativity of the O atom with a lone pair of electrons, there are two H-bond acceptors.

1. The given functional group is Aldehyde:

In this functional group, due to the high electronegativity of the O atom with a lone pair of electrons, there is one H-bond acceptor.

1. The given functional group is Alkyl halide (Only if X = F):

In this functional group, due to the high electronegativity of the F atom with a lone pair of electrons, there is one H-bond acceptor.

1. The given functional group is Epoxide:

In this functional group, due to the high electronegativity of the O atom with a lone pair of electrons, there is one H-bond acceptor.

1. The given functional group is Ester:

In this functional group, due to the high electronegativity of the O atoms with a lone pair of electrons, there are two H-bond acceptors.

1. The given functional group is Amine:

In this functional group, due to the high electronegativity of the N atom with a lone pair of electrons, there is one H-bond acceptor.

1. The given functional group is Amide:

In this functional group, due to the high electronegativity of the N atom with a lone pair of electrons, there is one H-bond acceptor.

(B) The functional groups possessing at least one H-bond donor and one H-bond acceptor are:

1) The given functional group is Hemiacetal:

In this functional group, there is one H-bond donor and two H-bond acceptors. The high electronegativity of the O atom ensures that the O-H bond is highly polar and gives the H atom a large partial positive charge. This sets up a strong attraction between the H atom and the oppositely charged acceptor.

2) The given functional group is Carboxylic acid:

In this functional group, there is one H-bond donor and two H-bond acceptors. The high electronegativity of the O atom ensures that the O-H bond is highly polar and gives the H atom a large partial positive charge. This sets up a strong attraction between the H atom and the oppositely charged acceptor.

1. The given functional group is Alcohol:

In this functional group, there is one H-bond donor and one H-bond acceptor. The high electronegativity of the O atom ensures that the O-H bond is highly polar and gives the H atom a large partial positive charge. This sets up a strong attraction between the H atom and the oppositely charged acceptor.

4) The given functional group is Phenol:

In this functional group, there is one H-bond donor and one H-bond acceptor. The high electronegativity of the O atom ensures that the O-H bond is highly polar and gives the H atom a large partial positive charge. This sets up a strong attraction between the H atom and the oppositely charged acceptor.

(C) The functional groups from the given table which possess no H-bond donor and no H-bond acceptor are:

1) The given functional group is Alkene:

In this functional group, there is no H atom which is covalently bonded to a strongly electronegative atom such as N, O, or F. Therefore, there is no H-bond donor and H-bond acceptor.

2) The given functional group is Thiol:

In this functional group, there is no H atom which is covalently bonded to a strongly electronegative atom such as N, O, or F. Therefore, there is no H-bond donor and H-bond acceptor.

3) The given functional group is Alkyne:

In this functional group, there is no H atom which is covalently bonded to a strongly electronegative atom such as N, O, or F. Therefore, there is no H-bond donor and H-bond acceptor.

1. The given functional group is Arene or aromatic compound:

In this functional group, there is no H atom which is covalently bonded to a strongly electronegative atom such as N, O, or F. Therefore, there is no H-bond donor and H-bond acceptor.

1. The given functional group is Alkyl halide (Only if X = Cl, Br, I):

In this functional group, there is no H atom which is covalently bonded to a strongly electronegative atom such as N, O, or F. Therefore, there is no H-bond donor and H-bond acceptor.

Conclusion

The H-bond donor and H-bond acceptor of the given compounds are predicted on the basis of the number of electronegative atoms that are covalently bonded with hydrogen atoms and with a large concentration of negative charge and lone pair of electrons.