What fundamental IUPAC rule is violated in the incorrect name "3-propylhexane"? — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

If a propyl group were attached to C3 of a hexane chain, the longest continuous carbon chain would actually follow through the propyl group, making it a 7-carbon chain (heptane). The correct name is 4-ethylheptane.