Chapter 5, Problem 5.39P

Interpretation Introduction

(a)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

Concept introduction:

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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The given molecule does not have any chiral center, and it is not a meso compound.

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. As there are no chiral centers, the molecule is not a meso compound.

Conclusion

The given molecule is determined as not a meso compound as it has no chiral center.

Interpretation Introduction

(b)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

Concept introduction:

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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The given molecule has one chiral center marked with $(*)$, and it is not a meso compound.

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 $\text{H}$. The chiral center is marked as $(*)$:

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

Conclusion

The chiral center in the given molecule is identified, and it is determined that the molecule is not a meso compound.

Interpretation Introduction

(c)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

Concept introduction:

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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The given molecule has one chiral center marked with $(*)$, and it is not a meso compound.

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 the 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, it is not a meso compound. The chiral center is marked as $(*)$:

Conclusion

The chiral center in the given molecule is identified, and it is determined that the molecule is not a meso compound.

Interpretation Introduction

(d)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The given molecule has no chiral center, and it is not a meso compound.

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. As there are no chiral centers, the molecule is not a meso compound.

Conclusion

The given molecule is determined as not a meso compound as it has no chiral center.

Interpretation Introduction

(e)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

Concept introduction:

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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The molecule has two chiral centers marked with $(*)$, and the molecule is not a meso compound.

It is not a meso compound.

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 $\text{H}$. The other carbon is bonded to four different groups, ${\text{CH(Cl)CH}}_{\text{3}}\text{,}{\text{CH}}_{\text{3}}\text{,}\text{Br}$, and $\text{H}$. These chiral centers are marked with $(*)$:

The molecule does not have symmetry plane; hence, it is not a meso compound.

Conclusion

The chiral centers in the given molecule are identified, and it is determined that the molecule is not a meso compound.

Interpretation Introduction

(f)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

Concept introduction:

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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The molecule has two chiral centers marked with $(*)$, and the molecule is not a meso compound.

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 $\text{H}$ marked with $(*)$.

The molecule has no plane of symmetry, and hence, it is not a meso compound.

Conclusion

The chiral centers in the given molecule are identified, and it is determined that the molecule is not a meso compound.

Interpretation Introduction

(g)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

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 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 5.39P

The molecule has two chiral centers marked with $(*)$, and the molecule is not a meso compound.

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 $\text{H}$ marked with $(*)$.

The molecule has no symmetry plane, and hence, it is not a meso compound.

Conclusion

The chiral centers in the given molecule are identified, and it is determined that the molecule is not a meso compound.

Interpretation Introduction

(h)

Interpretation:

All the chiral centers in the molecule are to be identified, and it is to be determined whether the molecule is meso.

Concept introduction:

The molecule with at least one chiral center having no plane of symmetry is called 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 plane of symmetry. Meso molecules are achiral.

Answer to Problem 5.39P

The given molecule has one chiral center marked with $(*)$, and it is not a meso compound.

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 as it has four different groups bonded.

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

Conclusion

The chiral center in the given molecule is identified, and it is determined that the molecule is not a meso compound.