Question

Options 1-4 are the different combinations of botanical pesticides. Which combination is a correct representation of the botanical pesticide Cinerin -II
1. Chrysanthemic acid + cinerolone
2. Pyrethric acid + cinirolone
3. Chrysanthemic acid + Pyrathrolone
4. Pyrethroic acid + Pyrethrolone

• A. Option 1 is a correct representation of the botanical pesticide Cinerin -II
• B. Option 2 is a correct representation of the botanical pesticide Cinerin -II
• C. Option 3 is a correct representation of the botanical pesticide Cinerin -II
• D. Option 4 is a correct representation of the botanical pesticide Cinerin -II

Hint:

To remember Pyrethrins chemistry:
Class I esters $\rightarrow$ contain Chrysanthemic acid.
Class II esters $\rightarrow$ contain Pyrethric acid.
Since Cinerin-II is in Class II, it must contain Pyrethric acid + cinerolone.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Pyrethrum is a natural botanical insecticide extracted from the flowers of Chrysanthemum cinerariifolium.
The insecticidal activity of pyrethrum is due to a mixture of six structurally related monoterpene esters known as pyrethrins.
These six esters are divided into two main classes based on their acid component:
1. Pyrethrins I: Esters containing chrysanthemic acid (Pyrethrin I, Cinerin I, and Jasmolin I).
2. Pyrethrins II: Esters containing pyrethric acid (Pyrethrin II, Cinerin II, and Jasmolin II).
These organic acids are esterified with one of three cyclopentenolone alcohols (rethrolones): pyrethrolone, cinerolone, or jasmolone.

Step 2: Detailed Explanation:
Let us analyze the specific chemical combinations of the active pyrethrins:
1. Pyrethrin I is the ester of chrysanthemic acid and pyrethrolone.
2. Pyrethrin II is the ester of pyrethric acid and pyrethrolone.
3. Cinerin I is the ester of chrysanthemic acid and cinerolone.
4. Cinerin II is the ester of pyrethric acid and cinerolone (spelled “cinirolone” in the question's typo).
5. Jasmolin I is the ester of chrysanthemic acid and jasmolone.
6. Jasmolin II is the ester of pyrethric acid and jasmolone.
The question asks for the correct chemical representation of Cinerin II.
According to the classification:
Cinerin II is composed of pyrethric acid and cinerolone (represented in option 2 as “Pyrethric acid + cinirolone”).
Option 1 represents Cinerin I (chrysanthemic acid + cinerolone).
Option 3 represents Pyrethrin I (chrysanthemic acid + pyrethrolone).
Option 4 represents Pyrethrin II (pyrethric/pyrethroic acid + pyrethrolone).
Therefore, Option 2 is the correct chemical representation of Cinerin II.

Step 3: Final Answer:
Thus, the correct choice is Option 2 (B).