Question

Double bond equivalent (degree of unsaturation) of (A) is-

(A) 1
(B) 2
(C) 3
(D) 4

Answer 1

Hint: A measurement which determines the total number of rings and α bonds is the degree of unsaturation. A formula for drawing chemical structures is used in organic chemistry. Although it gives no details about those elements separately- the specific numbers of rings or of double bonds (one pi − bond), or of triple bonds (two pi- bonds each) is given individually.

Complete step by step solution:
Formula used: $C+1-{\displaystyle \frac{H}{2}}-{\displaystyle \frac{X}{2}}+{\displaystyle \frac{N}{2}}$.
Catalytic hydrogenation of alkenes is caused by $H_2/Pt$. Because 1 mole of the reagent is available, only one double bond will be applied to $H_2$. So, two cyclopentane rings with a double relation should be present in compound A.
The double bond equivalent in A is three because of the presence of two rings and one dual bond. We may also use the formula to measure it.
The formula used to calculate double bond equivalent is-
$\Rightarrow C+1-{\displaystyle \frac{H}{2}}-{\displaystyle \frac{X}{2}}+{\displaystyle \frac{N}{2}}$
Where, C stands for carbon atoms, H for hydrogen atoms, X is for halogens.
Here, the value of C is 10
The value of H is two less than the number of H in the product = 18-2 = 16
Thus, Double bond equivalent is-
$$\begin{gathered} \Rightarrow C+1-{\displaystyle \frac{H}{2}}-{\displaystyle \frac{X}{2}}+{\displaystyle \frac{N}{2}} \\ \Rightarrow 10+1-{\displaystyle \frac{16}{2}} \\ \Rightarrow 10+1-8 \\ \Rightarrow 3 \end{gathered}$$

Hence, it is clear that option C is the correct option.

Note: The number of unsaturation in an organic molecule is DBE or double bond equivalent which is also known as the degree of unsaturation. Unsaturation refers to a double bond or a ring system. For example , 3 double bonds are possible for benzene and 1 ring gives us 4 DBE. A triple bond may also be considered as DBE = 2. X is the total number of halogens in the structure, that is, Cl, Br, F, and I. DBE measurement is not affected by the existence of the oxygen atom.