Question

Arrange herbicides in ascending order with respect to their first synthesis:
(A). Paraquat
(B). Pretilachlor
(C). Pendimethalin
(D). Simazine
(E). Sulfosulfuron
Choose the correct answer from the options given below:

• A. (D), (A), (C), (B), (E).
• B. (B), (D), (E), (A), (C).
• C. (D), (B), (E), (C), (A).
• D. (E), (A), (D), (B), (C).

Hint:

Remember that sulfonylureas (like sulfosulfuron) are modern, low-dose herbicides developed in the late 20th century, placing them last in the chronological timeline. Triazines (simazine) and bipyridiliums (paraquat) are older chemistries from the mid-20th century.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
To arrange these herbicides in ascending chronological order of their first synthesis or discovery, we must look at the historical development of weed science and the timeline of chemical herbicide introductions.

Step 2: Detailed Explanation:
Let us trace the history of discovery and commercialization for each of the given herbicides:

(D) Simazine: This is a symmetrical triazine herbicide discovered and synthesized by the Swiss company Geigy (later Ciba-Geigy) in1956. It was one of the earliest highly effective selective pre-emergence herbicides.

(A) Paraquat: Although the bipyridilium chemical group was synthesized earlier, the herbicidal properties of paraquat were first discovered by Imperial Chemical Industries (ICI) in1955, and it was commercially registered and introduced in1961/1962.

(C) Pendimethalin: This is a dinitroaniline herbicide developed by American Cyanamid and first synthesized and patented in the early1970s (around1972-1974).

(B) Pretilachlor: This is a chloroacetamide herbicide developed by Ciba-Geigy specifically for use in wet-seeded rice paddies, and was synthesized and introduced in the early1980s (around1982).

(E) Sulfosulfuron: This belongs to the sulfonylurea class of herbicides, which are characterized by very low application rates. It was synthesized and introduced much later, in the late1990s (around1997), to control grassy weeds in wheat.
Arranging these in ascending chronological order gives: Simazine (1956) \(\rightarrow\) Paraquat (1960) \(\rightarrow\) Pendimethalin (1972) \(\rightarrow\) Pretilachlor (1982) \(\rightarrow\) Sulfosulfuron (1997).
This corresponds to the sequence: (D), (A), (C), (B), (E).

Step 2: Final Answer:
The correct option is (A).