Question

Ethanedinitrile (EDN) is used as fumigant to control pests, weeds, and naematodes. Find sum of degree of unsaturation, no. of electrons involved in pi bond formation and number of sigma bonds of EDN.

Answer 1

15

Answer 2

Solution:

1. Structure:
   Ethanedinitrile (cyanogen) has the structure

   $$\text{N}\equiv \text{C} - \text{C}\equiv \text{N}$$

   with two triple bonds (N≡C) and a single C–C bond.

2. Degree of Unsaturation (DoU):
   Each triple bond contributes 2 degrees of unsaturation. Thus,

   $$\text{DoU} = 2 \times 2 = 4.$$

3. Electrons in π Bonds:
   Each triple bond has 2 π bonds and each π bond consists of 2 electrons. Therefore,

   $$\text{Total π electrons} = 2\ (\pi\text{-bonds per triple}) \times 2\ (\text{electrons per π-bond}) \times 2\ (\text{triple bonds}) = 8.$$

4. Number of σ Bonds:

   • Each triple bond has 1 σ bond → 2 σ bonds from the two triple bonds.
   • Plus, there is 1 σ bond from the C–C single bond. $$\text{Total σ bonds} = 2 + 1 = 3.$$

5. Final Sum:

   $$\text{Sum} = \text{DoU} + (\text{π electrons}) + (\text{σ bonds}) = 4 + 8 + 3 = 15.$$

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Explanation (minimal):
EDN (cyanogen) is $\text{N}\equiv \text{C} - \text{C}\equiv \text{N}$. Each triple bond gives 2 DoU and 2 π bonds (4 π electrons per bond pair), and the C–C bond is a σ bond. So, DoU = 4, π electrons = 8, σ bonds = 3 and the total sum is $4+8+3=15$.