Question

Which from following compounds does NOT contain nitrogen in it?

• A. Thiophene
• B. Pyridine
• C. Pyrrole
• D. Piperidine

Hint:

Memorize the "Big Three" 5-membered aromatic heterocycles:
- Pyrrole contains Nitrogen (N).
- Furan contains Oxygen (O).
- Thiophene contains Sulphur (S).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks us to identify the heterocyclic organic compound from the given list that does not possess a nitrogen atom in its molecular ring structure.

Step 2: Detailed Explanation:
Let's review the fundamental chemical structures of these common heterocyclic rings:
- (b) Pyridine: A 6-membered aromatic ring containing one Nitrogen atom ($C_5H_5N$).
- (c) Pyrrole: A 5-membered aromatic ring containing one Nitrogen atom ($C_4H_4NH$).
- (d) Piperidine: A fully saturated 6-membered ring containing one Nitrogen atom (it is the hydrogenated, non-aromatic version of pyridine).
- (a) Thiophene: A 5-membered aromatic ring where the heteroatom is Sulphur, not nitrogen ($C_4H_4S$).

Step 3: Final Answer:
Thiophene contains sulphur, not nitrogen, matching option (a).