IUPAC nomenclature of protonated aminoacids

What is the IUPAC systematic name for the above compound.

So I know that carboxylic acids have highest priority. Now the length of carbon chain is 7. So I think the name should be 7-ammonioheptanoic acid. Am I correct?

• Since this is a cation, I would suppose there should be "-ium" somewhere. For the neutral molecule, 7‐aminoheptanoic acid is correct IMO. – andselisk May 23 at 5:59
• @andselisk Ig, OP used ammonio- which is used as prefix for $\ce{NH4+}$ more commonly. Name seems correct to me, don't know if it's legitimate name according to IUPAC rules.. – Zenix May 23 at 7:00
• @Zenix My bad, you are correct, IUPAC Blue Book from 2013 indeed allows to denote $\ce{-\overset{+}{N}H3}$ with ammonio-. – andselisk May 23 at 7:13
• ChemDraw dubiously says the name is 6-carboxyhexan-1-aminium ... – Aniruddha Deb May 23 at 7:29

1 Answer

Interestingly, Ammonium salts come above acids in the seniority table for functional groups (Reference: Wikipedia). Also, the ion in question has an alkyl group attached to it, which makes the suffix aminium rather than the commonly used ammonium. (Reference: Gold Book, Wikipedia) This means that the correct name of the compound is 6-carboxyhexan-1-aminium. This was also checked with ChemDraw online, as mentioned in the comments.

• "suffix" or "prefix" (or am I turned around somehow)? – Eric Towers May 23 at 18:27
• Suffix=after root word, Prefix=before root word. So in this name, the prefix is carboxy and suffix is aminium – Aniruddha Deb May 24 at 4:07