3
$\begingroup$

What is the IUPAC name of this structure?

Skeletal formula of compound CC(C)(C)C1C(CCC)CCC(CCCCCCC)CCCC1

I've actually came up with two names, the first one is "1-tert-butyl-5-heptyl-2-propylcyclononane" and the other one is "1-(1,1-dimethylethyl)-5-heptyl-2-propyl-cyclononane". I'm confused which one is right or if both are correct.

$\endgroup$
  • 1
    $\begingroup$ @KarstenTheis I've actually came up with two names, the first one is "1-tert-butyl-5-heptyl-2-propylcyclononane" and the other one is "1-(1,1-dimethylethyl)-5-heptyl-2-propyl-cyclononane". I'm confused which one is right or if both are correct. $\endgroup$ – user76215 Mar 26 at 17:55
  • $\begingroup$ So your question is not about how to name it, but rather whether the tBu group should be written as "tert-butyl" or "1,1-dimethylethyl". $\endgroup$ – orthocresol Mar 26 at 18:02
  • $\begingroup$ Note also that there should not be a hyphen directly before cyclononane; one of your proposed names is correct in this regard and the other isn't. $\endgroup$ – orthocresol Mar 26 at 18:06
4
$\begingroup$

According to Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book) (P-57.1.2), the preferred prefix for $\ce{-C(CH3)3}$ is "tert-butyl".

As for where it comes in the name:

P-14.5 Alphanumerical order
[...] Alphanumerical order is applied as follows in organic nomenclature. Nonitalic Roman letters are considered first, unless used as locants or part of a compound or composite locant [...]

so the prefix tert is not considered (except in more complicated cases, cf. P-14.5.3). Therefore, the preferred IUPAC name for the molecule in question is 1-tert-butyl-5-heptyl-2-propylcyclononane. Note that there are no parentheses around tert-butyl.

Be warned: tert-butyl has received special treatment from IUPAC on this front. Other non-systematic prefixes have fallen from favour, most notably isopropyl, sec-butyl, and isobutyl. The preferred prefixes are respectively propan-2-yl, butan-2-yl, and 2-methylpropyl.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.