Q4.28P - Chemistry: Molecular Nature Of Matter And Change

Question

Many important compounds in the chemical industry are derivatives of ethylene $\mathbf{\left(}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{4}}\mathbf{\right)}$ . Two of them are acrylonitrile and methyl methacrylate.

Complete the Lewis structures for these molecules, showing all lone pairs. Give approximate values for bond angles a through f, and give the hybridization of all carbon atoms. In acrylonitrile and methyl methacrylate indicate which atoms in each molecule must lie in the same plane. How many s bonds and how many p bonds are there in acrylonitrile and methyl methacrylate?

Step-by-Step Solution

Answer

Acrylonitrile –Bond angle , ,  .   The hybridization of the carbon atoms are given below.

C-1 = ${\text{sp}}^{\text{2}}$  

C-2 =  ${\text{sp}}^{\text{2}}$

C-3 =  $\text{sp}$ 

There are $6\mathrm{\sigma }$  bond and  $3\mathrm{\pi }$ bonds.

Methyl methacrylate – the values of the bond angle are given below’

$\mathrm{e}\approx {120}^{\circ }$ ,$d\approx {120}^{\circ }$ , $f\approx {109.5}^{\circ }$

C-1 =  ${\text{sp}}^3$

C-2=   ${\text{sp}}^{\text{2}}$

C-3=  ${\text{sp}}^{\text{2}}$

C-4 =  ${\text{sp}}^{\text{2}}$

C-5 =  ${\text{sp}}^{\text{3}}$

There are $14\mathrm{\sigma }$ bond and  $2\mathrm{\pi }$ bonds.

Step 1

Acrylonitrile –The bond angles are  $\mathrm{a}\le {120}^{\circ }$ ,$b\ge {120}^{\circ }$ , $c={180}^{\circ }$.

Carbon 1 and carbon 2 are $s{p}^2$ hybridized while the  carbon 3 is  hybridized. All the atoms are in the same plane. There are $6\mathrm{\sigma }$  bond and $3\mathrm{\pi }$ bonds. The Lewis structure is given below.

The Lewis structure 

Step 2

Methyl methacrylate- The bond angles are  $e\approx {120}^{\circ }$, $d\approx {120}^{\circ }$,  $f\approx {109.5}^{\circ }$

Carbon 1 and  carbon 5 are  $s{p}^2$ hybridized while carbon 2, carbon 3, carbon 4 are $s{p}^2$   hybridized. There are $14\sigma$  bond and $2\mathrm{\pi }$  bonds. Carbons 2 , 3 ,4and 5 lie in the same plane. The Lewis structure is given below.

The Lewis structure