I want to abbreviate pseudoisocytosine. Should it be "ΨiC" or "ΨiC"?

I would usually write "sec-butyl", "tert-butyl", etc, and using "t-BuOH" for "t-butyl alcohol. I usually see, in respectable places, "i-PrOH" for isopropanol, and that what I have done up till now.

The Wikipedia for chemical naming conventions notes that "cyclo, iso, neo, and spiro are considered part of a chemical name (such as isopropanol) and not considered prefixes. No hyphens or italics are used in these cases."

IUPAC writes "isopropyl" prefix.

What is correct?


1 Answer 1


I don't have the time for a very in-depth answer at the moment. However, if you look at P-29.6 of the 2013 Blue Book, you can see what they italicise and what they don't. (Just do a Ctrl-F for the relevant words.)


  • sec-butyl is italicised
  • tert-butyl is italicised
  • tert-pentyl is italicised
  • o-tolyl is italicised
  • isopropyl is not italicised
  • isobutyl is not italicised
  • neopentyl is not italicised

It should be pointed out that of all these, only tert-butyl is a preferred prefix. The section linked above makes this clear. But in most cases, that probably needn't concern you.

As for abbreviations, these are covered in the 2008 IUPAC recommendations on Graphical Representation Standards for Chemical Structure Diagrams. See in particular Table II on page 406, which gives the following forms: iPr, iBu, s-Bu, and t-Bu (which is in line with the Blue Book). It says that if you choose these abbreviations, then explicitly defining them is unnecessary.

(Of course, you can choose whatever abbreviation you like, as long as you define it. The text accompanying Table II makes that clear. It also says that the non-italicised forms are fine too.)

Authors are welcome to create their own abbreviations as well, but any abbreviations not included in the list below should be defined clearly when they are used. [...] Several of the abbreviations listed below include portions of the text in italics. The italicization shown is the preferred formatting of those abbreviations. However, the corresponding forms without italicization are also acceptable.

  • $\begingroup$ 1. Is this the most up-to-date version? Sorry, I don't know this. 2. Just making sure: So where I see "i-PrOH", when not explicitly defined, is wrong? $\endgroup$ Commented Aug 13, 2022 at 22:27
  • 5
    $\begingroup$ 1) Yes, the 2013 recommendations are the most recent. You can see this on e.g. Wikipedia 2) It depends on how you define 'wrong'. Sure, it's not in line with IUPAC recommendations. If you're thinking about a journal, they may have their own set of rules, which may take precedence over IUPAC recommendations. And sometimes, it simply doesn't matter. Plenty of things out there are not in line with IUPAC recommendations, and people still understand them just fine. $\endgroup$ Commented Aug 13, 2022 at 22:51

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