Would the given organic compound be called "3,4-diethyl-3,7,7-trimethylnonane" with IUPAC naming rules?

picture of organic molecule

I don't really know if this should be called 3,4-diethyl-3,7,7-trimethylnonane, because it could also be called 6,7-diethyl-3,3,7-trimethyl something.

I am trying to do this by IUPAC rules.

  • $\begingroup$ Which locant set do you think is lower, 3,3,4,7,7 or 3,3,6,7,7? $\endgroup$
    – user7951
    Jul 16, 2020 at 18:21
  • $\begingroup$ @FadedGiant i think it would be the first one, but is that the reason why it is correct? I thought it was because it also needed to be numerically lowest -> highest $\endgroup$
    – user95951
    Jul 16, 2020 at 18:45

1 Answer 1


Yes, your naming would be correct. For saturated hydrocarbons, the first point of difference rule takes precedence after the longest carbon chain. To apply this rule, the locants of each set are ordered numerically in a list from lowest to highest, and the series that has the lower number at the first occasion of difference is determined as the lower locant set, regardless of what comes after this first point of difference. In this case, "3,3,4,7,7" would be the lower locant set than "3,3,6,7,7", because 4 is lower than 6.


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