Chapter 5, Problem 5.38P

Interpretation Introduction

(a)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.38P

The given molecule is not a chiral molecule.

Explanation of Solution

The structure of the given molecule is

A chiral center must be an ${\text{sp}}^3$ hybridized atom bonded to four different groups. The carbon atoms in the benzene ring are all ${\text{sp}}^2$ hybridized and therefore cannot be chiral centers. Hence, this is not a chiral molecule.

Conclusion

The given molecule is identified as achiral on the basis of the presence of a chiral center.

Interpretation Introduction

(b)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.38P

The given molecule is a chiral molecule.

Explanation of Solution

The structure of the given molecule is

In this molecule, the nitrogen atom is a chiral center bonded to four different groups ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}\text{,}{\text{CH(CH}}_{\text{3}}{\text{)}}_{\text{2}}{\text{, CH}}_{\text{3}}\text{,}$ and $\text{H}$. As this molecule has only one chiral center, it cannot possess any symmetry, and hence, this is a chiral molecule.

Conclusion

The given molecule is identified as chiral on the basis of the presence of a chiral center.

Interpretation Introduction

(c)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.38P

The given molecule is a chiral molecule.

Explanation of Solution

The structure of the given molecule is

The molecule consists of a ring made up of five carbon atoms and one nitrogen atom. The nitrogen atom is bonded to three different groups having pyramidal shape and a non-bonded electron pair pointing to the unoccupied tetrahedral corner. This makes the nitrogen a chiral center.

As this molecule has only one chiral center, it cannot possess any symmetry, and hence, this is a chiral molecule.

Conclusion

The given molecule is identified as chiral on the basis of the presence of a chiral center.

Interpretation Introduction

(d)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.38P

The given molecule is not a chiral molecule.

Explanation of Solution

The structure of the given molecule is

A chiral center must be an ${\text{sp}}^{\text{3}}$ hybridized atom bonded to four different groups. The double bonded carbons are ${\text{sp}}^2$ hybridized and, therefore, cannot be chiral centers. In the alkyl substituent, the terminal carbons have three hydrogen atoms bonded to them. The remaining three carbon atoms in the chain have two hydrogen atoms bonded to them.

Therefore, these carbon atoms are also not chiral centers. Hence this is not a chiral center.

Conclusion

The given molecule is identified as achiral on the basis of the presence of a chiral center.

Interpretation Introduction

(e)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.38P

The given molecule is not a chiral molecule.

Explanation of Solution

The structure of the given molecule is

The given molecule possesses two chiral carbons. One carbon is bonded to four different groups, ${\text{CH(Br)CH}}_{\text{3}}\text{,}{\text{CH}}_{\text{3}}\text{,}\text{Cl}$, and $\text{H}$ marked with red. The other carbon is bonded to four different groups, ${\text{CH(Cl)CH}}_{\text{3}}\text{,}{\text{CH}}_{\text{3}}\text{,}\text{Br}$, and $\text{H}$ marked with blue.

As the bonded atoms are not exactly same, the molecule does not have a symmetry plane; hence, it is a chiral molecule.

Conclusion

The given molecule is identified as chiral on the basis of the presence of a chiral center.

Interpretation Introduction

(f)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral. The molecule with an inversion center or center of symmetry is also achiral.  An inversion center is a point in the molecule through which all other atoms can be reflected ${\text{180}}^{\text{o}}$ into another identical atom.

Answer to Problem 5.38P

The given molecule is not a chiral molecule.

Explanation of Solution

The structure of the given molecule is

The given molecule possesses an inversion center indicated by the blue dot, which reflects all the atoms into identical atoms through ${\text{180}}^{\text{o}}$.

As the molecule has an inversion center, it is not a chiral molecule.

Conclusion

The given molecule is identified as achiral on the basis of the presence of a chiral center.

Interpretation Introduction

(g)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral. The molecule with an inversion center or center of symmetry is also achiral.  An inversion center is a point in the molecule through which all other atoms can be reflected ${\text{180}}^{\text{o}}$ into another identical atom.

Answer to Problem 5.38P

The given molecule is not a chiral molecule.

Explanation of Solution

The structure of the given molecule is

The given molecule possesses two chiral carbons bonded to four different groups, ${\text{CH(Cl)CH}}_{\text{3}}\text{,}{\text{CH}}_{\text{3}}\text{,}\text{Cl}$, and $\text{H}$. The molecule has no symmetry plane, and hence, it is a chiral molecule.

Conclusion

The given molecule is identified as chiral on the basis of the presence of a chiral center.

Interpretation Introduction

(h)

Interpretation:

It is to be identified whether the given molecule is chiral.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called a chiral molecule. A chiral center is a tetrahedral stereocenter. The atom at the chiral center must be ${\text{sp}}^{\text{3}}$ hybridized and bonded to four different atoms or groups. Carbon and nitrogen are both capable of forming four bonds; therefore, they can be chiral centers if bonded to four different atoms or groups. A molecule with at least two chiral centers having a plane of symmetry is called a meso molecule. A plane that bisects the molecule into two halves that are mirror images of each other is called as a plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.38P

The given molecule is not a chiral molecule.

Explanation of Solution

The structure of the given molecule is

The molecule consists of a ring made up of four carbon atoms and one oxygen atom with a substituted methyl group. The carbon having the methyl substituent is a chiral center that has four different groups bonded.

The molecule does not possess any symmetry plane; hence, it is a chiral molecule.

Conclusion

The given molecule is identified as chiral on the basis of the presence of a chiral center.