Q11.25P - Chemistry: Molecular Nature Of Matter And Change

Question

2-Butene ($\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}\mathit{H}\mathbf{=}\mathit{C}\mathit{H}\mathit{C}{\mathit{H}}_{\mathbf{3}}$) is a starting material in the manufacture of lubricating oils and many other compounds. Draw two different structures for 2-butene, indicating the sigma and pi bonds in each.

Step-by-Step Solution

Answer

Answer

The 2-Butene can be formed by the 2-ethylene dimerization forming geometrical isomers having five sigma and one pi-bond.

Step 1: Bonding

Bonding may be defined as the attraction forced by both the atom on each other.

In bonding, there can be the involvement of a pair of electrons or two pairs of the electron.

As the electronegativity difference between the atoms increases, the attraction between the electrons increases and a strong bond is formed.

Step 2: Geometrical Isomers

There is sigma and pi-bond present in the 2-butene which can be represented by the geometrical isomer, i.e., $\mathit{c}\mathit{i}\mathit{d}\mathbf{-}\mathbf{2}\mathbf{-}\mathit{b}\mathit{u}\mathit{t}\mathit{e}\mathit{n}\mathit{e}$ and $\mathit{t}\mathit{r}\mathit{a}\mathit{n}\mathit{s}\mathbf{-}\mathbf{2}\mathbf{-}\mathit{b}\mathit{u}\mathit{t}\mathit{e}\mathit{n}\mathit{e}$.

In geometrical isomers, there is a change in the position of the methyl- group and because of that, there is a change in the repulsion between molecules.

The formation of the geometrical isomers has similar pi and sigma bonds as there is no change in the double bond.

Pi-bond is comparatively weaker than sigma.

The number of sigma bonds is five (5).

The number of pi-bonds is one between the two carbon atoms.