Question

The number of sigma $\left(\sigma \right)$ and pi $\left(\pi \right)$ bonds present in 1, 3, 5, 7-octatetraene respectively are:

• A. 14 and 3
• B. 17 and 4
• C. 16 and 5
• D. 15 and 4
• E. 16 and 3

Answer 1

The correct option is B

17 and 4

Firstly, lets make the structure of 1,3,5,7-Octatetraene.

Octa $\Rightarrow$ 8 carbon

$\Rightarrow C-C-C-C-C-C-C-C$

Now, tetraene means 4 double bonds at $C_1,C_3,C_{5}and{C}_7$

$\stackrel{H}{\stackrel{|}{\underset{H}{\underset{|}{C}}}}=\stackrel{H}{\stackrel{|}{C}}-\stackrel{H}{\stackrel{|}{C}}=\stackrel{H}{\stackrel{|}{C}}-\stackrel{H}{\stackrel{|}{C}}=\stackrel{H}{\stackrel{|}{C}}-\stackrel{H}{\stackrel{|}{C}}=\stackrel{H}{\stackrel{|}{\underset{H}{\underset{|}{C}}}}$

Now,calculate $\sigma$ bonds $\Rightarrow$ 17

4 double bonds $\Rightarrow$ 4 $\pi$ bonds.