reference request - What is the formally correct notation of t-Bu, i-Pr, p-NO2, n-Bu, a-HCl, etc.?

In chemical notation, can I safely assume that the notation of

• a single lower-case latin character


• followed by a hyphen



• followed by an Element upper-case latin character (and possibly more characters)

should always be typeset as

• italic lower-case character


• hyphen (i.e. never is a bond)


• element following characters

This question is regarding the further improvement of mhchem.

I know that not all of them stand for the same concept, but I assume they share the same typographical representation. Beware, I am no chemist. And because I don't know the name of these notations, I could not find them in the colored IUPAC books.

The notation is quite rare. There were only 21 usages in 43k \ce calls extracted from chemistry.SE:

(p-NO2Ph)_2CO
t-BuO-
i-Pr
t-Bu
R=i-Pr
n-BuNH2
(c-Hex)2BCl

a-HCl  // should this be \alpha?


1s-H  // what is this?

Answer

tl;dr: That's probably a good approach.

So, there are at least three different things here. None of these abbreviations are standardised as far as I'm aware[1], so whatever is done is going to be just as non-standard as any other approach.

1. 
   

   Specific shorthands for alkyl functional groups: t-Bu, i-Pr, n-Bu, c-Hex

   
   

   I've seen the method you've suggested used for these, and also the first three with superscripted initial characters, e.g. $^{\textrm{t}}\textrm{Bu}$ and $^{\textrm{i}}\textrm{Pr}$, and I'd never seen the last one until I read this question. I've also seen them written simply as tBu, iPr, and nBu. They're abbreviations for tert-butyl, isopropyl, n-butyl (straight-chain), and cyclo-hexyl respectively. (Here are links for IUPAC References for non-cyclic and cyclic alkanes.)

   
   



2. 
   

   Substitution points on a benzene ring: (p-NO2Ph)_2CO

   
   

   This example denotes a para- substituted phenyl group (confusingly, benzyl refers to a $\ce{C6H5-CH2 -}$ group). The other options here are ortho- and meta-, which I would personally not find it confusing or uncommon to see abbreviated to o- and m- respectively, and $\ce{{\it p}-NO2Ph}$ seems a perfectly reasonable interpretation of what the person has written here.

   
   


3. 
   

   Electronic configuration labels: 1s-H

   
   

   This seems like using an atomic orbital label (1s) as a hyphenated specifier for the hydrogen: I don't think it's a standard form of writing that at all, but the method you propose would presumably italicise the s, which would be fine -- the atomic orbital labels like this are often italicised.

   
   


4. 
   

   Whatever the a-HCl is: I don't know.

   
   
   

   I couldn't find anything that looked appropriate for this one.

   
   

Most importantly, I can't think of any counter-examples where that wouldn't be a sensible thing to do.

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[1] Edit: I defer to @Loong's superior mastery of the ways of IUPAC in their answer.