Q65. - Organic Chemistry

Question

Question: What orbitals are used to form each highlighted bond? For multiple bonds, indicate the orbitals used in individual bonds.

                                        a.

                                           b.

                                           c.

Step-by-Step Solution

Answer

Answer

    a.

• [1]: This carbon and hydrogen atom is formed by the orbitals $\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{H}\left(1\mathrm{s}\right)$ .
• [2]: The sigma bond $\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{C}\left({\mathrm{sp}}^2\right)$ and the$\mathrm{\pi } \mathrm{Cp}-\mathrm{Cp}$ .
• [3]: The bond between the two carbon atoms involves $\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{C}\left({\mathrm{sp}}^3\right)$ orbitals.

b.

• [1]: This carbon-carbon bond involves $\mathrm{C}\left({\mathrm{sp}}^3\right)-\mathrm{C}\left({\mathrm{sp}}^2\right)$ orbitals.
• [2]: This carbon-oxygen bond involves $\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{O}\left({\mathrm{sp}}^2\right)$ orbitals for the sigma bond and$\mathrm{Cp}-\mathrm{Op}$  for the $\mathrm{\pi }$ bond.

    c.

• [1]: This carbon-hydrogen bond involves the $\mathrm{C}\left(\mathrm{sp}\right)-\mathrm{H}\left(1\mathrm{s}\right)$ orbitals.
• [2]: The carbon-carbon sigma bond involves $\mathrm{C}\left(\mathrm{sp}\right)-\mathrm{C}\left(\mathrm{sp}\right)$ and the two  bonds are formed by $\mathrm{Cp}-\mathrm{Cp}$.
• [3] : This carbon-bond is formed by $\mathrm{C}\left(\mathrm{sp}\right)-\mathrm{C}\left({\mathrm{sp}}^2\right)$.
• [4]: This carbon-nitrogen bond involves$\mathrm{N}\left({\mathrm{sp}}^2\right)-\mathrm{C}\left({\mathrm{sp}}^3\right)$ .

Step-by-Step Solution Step 1: Determine the hybridization of the atoms of the highlighted bonds.

Structure a. 

• The first highlighted bond [1] is formed between the carbon and the hydrogen atom. The hybridization of the carbon atom is ${\mathrm{sp}}^2$ because it has three groups attached to it.

It is also forming a double bond with the neighboring carbon atom. The hydrogen atom does not show any hybridization.

 

• The second highlighted bond [2] is formed between the two carbon atoms and is a double bond. The hybridization of the carbon atoms is ${\mathrm{sp}}^2$ .

 

• The third highlighted bond [3] is a carbon-carbon single bond and is formed between the two carbon atoms with ${\mathrm{sp}}^{2 }\mathrm{and} {\mathrm{sp}}^3$ hybridization.

 

 

Structure b.

• The highlighted bond [1] in this structure is formed between the two carbon atoms, with one having ${\mathrm{sp}}^3$ hybridization and the other having ${\mathrm{sp}}^2$ hybridization.
• The second highlighted bond [2] in this structure is formed between a hybridized carbon atom and a ${\mathrm{sp}}^2$hybridized oxygen atom.

 

Structure c.

• The first highlighted bond [1] in this structure is formed between $\mathrm{sp}$-hybridized carbon and the hydrogen atom. The hydrogen atom does not follow any hybridization.
• The second highlighted bond [2] is formed between two $\mathrm{sp}$-hybridized carbon atoms.
• The third highlighted bond [3] is formed between the $\mathrm{sp}$-hybridized and the hybridized carbon atoms.
• The fourth highlighted bond is formed between the ${\mathrm{sp}}^2$hybridized nitrogen atom and${\mathrm{sp}}^3$ the hybridized carbon atom.

Step 2: Kind of orbitals involved in the highlighted bonds

From the type of hybridization, the kind of orbitals involved in bonding can be easily determined for every bond in the given structure.

Structure a.

• The orbitals involved in the first highlighted bond [1] are $\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{H}\left(1\mathrm{s}\right)$. The hydrogen atom does not undergo any hybridization; therefore, the 1s orbital of hydrogen is directly involved in bonding.

 

• The second highlighted bond [2] is a C=C double bond. The double bond consists of one sigma and one $\mathbf{\pi }$ bond. The $\mathbf{\pi }$ bond is formed by the side-wise overlap of the unhybridized p orbitals.

 

 

• The orbitals involved in the formation of a C-C sigma bond are . The orbitals i$\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{C}\left({\mathrm{sp}}^2\right)$ involved for C-C $\mathrm{\pi } \mathrm{are} \mathrm{Cp}-\mathrm{Cp}$ .

 

• For the third highlighted bond [3], the orbitals$\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{C}\left({\mathrm{sp}}^3\right)$ involved in bonding are .

 

 

Structure b.

• The orbitals used to form the highlighted bond [1] are .
• For the second highlighted bond [2], the orbitals involved are $\mathrm{C}\left({\mathrm{sp}}^2\right)-\mathrm{O}\left({\mathrm{sp}}^2\right)$ for the C-O sigma bond and $\mathrm{Cp}-\mathrm{Op}$. The unhybridized p orbitals of both carbon and oxygen atoms are involved in the formation of a$\mathbf{\pi }$  bond. 

 

Structure c.

• The highlighted bond [1] is formed by$\mathrm{C}\left(\mathrm{sp}\right)-\mathrm{H}\left(1\mathrm{s}\right)$ .
• The second highlighted bond [2] is a carbon-carbon triple bond consisting of one C-C sigma bond and two C-C bonds. The sigma bond is formed by$\mathrm{C}\left(\mathrm{sp}\right)-\mathrm{C}\left(\mathrm{sp}\right)$ orbitals. The two  bonds are formed by the sideways overlap of the p orbitals of both the carbon atoms, i.e.,$\mathrm{Cp}-\mathrm{Cp}$.
• The third highlighted bond [3] is formed between $\mathrm{C}\left(\mathrm{sp}\right)-\mathrm{C}\left({\mathrm{sp}}^2\right)$ orbitals.
• The fourth highlighted bond [4] between nitrogen and carbon is formed by$\mathrm{N}\left({\mathrm{sp}}^2\right)-\mathrm{C}\left({\mathrm{sp}}^3\right)$ orbitals.