# Clarification on IUPAC nomencalture

This is 1,6-dimethyl-cyclohexene. Why cannot this same structure have the IUPAC name 1,2-dimethyl-cyclohexene. In the given picture the locant sum comes to 7 but in my case it comes to 3, implying that my answer is in accordance with the rules. Aren't the alkyl groups supposed to be given the lowest number as per lowest locant sum rule?

• Look at this maybe it can help :) – ParaH2 Mar 25 '18 at 16:00
• How does the double bond influence the numbering? – J_B892 Mar 25 '18 at 16:05
• Note that the widely-cited "sum of locants" rule is incorrect. See: IUPAC nomenclature: “Smallest sum of locants”? and the answers therein. – orthocresol Mar 25 '18 at 16:10
• So like as in unsaturated compounds, in alicyclic compounds, the higher sum of locant structure is the correct one – J_B892 Mar 25 '18 at 16:11
• Because the -ene must have the lowest sum of locants. We are naming a (cyclic) alkene, after all. Your suggestion would have otherwise the methyl groups at both sides of the double bond. – Alchimista Mar 25 '18 at 16:13

• Yes, but lowest number goes to the most substituted $\ce {sp^2}$ carbon (if double bond has the highest priority). – Mathew Mahindaratne Mar 26 '18 at 6:14