# Is the name of this chemical 3-oxopropanoic acid?

Is the name of this chemical 3-oxopropanoic acid?

I included "oxo"- for the aldehyde group, and "-oic acid" for the carboxylate group.

However, I'm unsure whether this is the correct name since I cannot find it on the internet, while I can find almost all other names I've been trying to figure out.

• – user7951 Dec 28 '15 at 19:50

The name ‘3-oxopropanoic acid’ for the compound $\ce{OHC-CH2-COOH}$ given in the question is correct.

According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the order of seniority of classes in decreasing order of seniority is as follows.

(…)
7. acids
(…)
15. aldehydes
(…)

Thus, the carboxylic acid group has priority to be cited as a suffix.

Systematic names of carboxylic acids are formed as follows:

P-65.1.2 Systematic names

Carboxylic acids are named substitutively using the suffix ‘oic acid’ or ‘carboxylic acid’ and the prefix ‘carboxy’ to describe carboxy groups that cannot be included as the principal characteristic group or to express the carboxy group in the presence of a higher principal characteristic group.

P-65.1.2.1 Carboxylic acid groups, $\ce{-COOH}$, that conceptually replace a $\ce{-CH3}$ group of methane or terminate an unbranched hydrocarbon chain are named by replacing the final ‘e’ of the name of the corresponding hydrocarbon by the suffix ‘oic acid’. No locants are necessary to denote the positions of the carboxylic acid groups in a hydrocarbon chain; (…). Except for (…), systematically formed names are preferred IUPAC names; (…)

Therefore, the preferred IUPAC name (PIN) of the unmodified carboxylic acid is ‘propanoic acid’. (Note that the retained name ‘propionic acid’ may be used in general nomenclature.)

Aldehydes can be systematically named in various ways. Monoaldehydes derived from alkanes are preferably named substitutively using the suffix ‘al’. In this case, however, this method cannot be used since the carboxylic acid group has priority to be cited as a suffix. Therefore, the aldehyde group has to be expressed by a prefix as follows:

P-66.6.1.3 In the presence of a characteristic group having priority to be cited as a suffix or when present on a side chain, a $\ce{-CHO}$ group is expressed by the preferred prefix ‘oxo’ if located at an end of a carbon chain, or, otherwise, by the preferred prefix ‘formyl’.

Thus, the PIN for the complete structure is ‘3-oxopropanoic acid’.

The corresponding name that is formed by using the prefix ‘formyl’ is ‘formylacetic acid’. Such names are not acceptable as PINs but may be used in general nomenclature.

Furthermore, a special rule for aldehydic acids applies to the given compound:

P-65.1.6.3 Aldehydic acids

When a dicarboxylic acid has a retained name (…) and when one of its carboxy groups is replaced by a formyl group, $\ce{-CHO}$ (…), the resulting structure is called an aldehydic acid and, in general nomenclature may be named by replacing the ending ‘ic acid’ of the name of the dicarboxylic acid by the ending ‘aldehydic acid’. Preferred IUPAC names for aldehydic acids derived from all dicarboxylic acids are constructed systematically. The prefix ‘formyl’ is used in preferred IUPAC names, except for a $\ce{-CHO}$ group at the end of an acyclic chain, which is designated by the prefix ‘oxo’.

For the compound given in the question, the PIN of the corresponding dicarboxylic acid is ‘propanedioic acid’.

This dicarboxylic acid also has the retained name ‘malonic acid’, which may be used in general nomenclature. Hence, according to P-65.1.6.3, the corresponding aldehydic acid may be named ‘malonaldehydic acid’ in general nomenclature.

By way of comparison, for the analogous example $\ce{OHC-CH2-CH2-COOH}$, all three corresponding names are explicitly mentioned in the Blue Book:

• 4-oxobutanoic acid (PIN)
• 3-formylpropanoic acid
• succinaldehydic acid

• Probably worth noting that many biochemists would call this compound "malonic semialdehyde", as it is derived from the common biochemical/metabolite malonic acid by reduction of one (but not both, thus the "semi") of the acid moieties to an aldehyde. – Curt F. Dec 29 '15 at 5:26

3-Oxopropanoic acid (if carbon of aldehyde is numbered, use "oxo" as prefix) is correct IUPAC-name for the given chemical compound.

Formylethanoic acid (if carbon of aldehyde is not numbered, use "formyl" as prefix) is also correct IUPAC -name.

• A compound typically has one (in digits: 1) correct systematic IUPAC name. – Jan Dec 31 '15 at 16:43
• If we are using formyl prefix and parent chain has two carbon only of an acid and "1" is considered, it is wrong. Suppose, in case of "2-formylpropanoic acid" and "3-formylpropanoic acid" both are different compound and correct. "1-formylpropanoic acid" is incorrect IUPAC and even also this compound doesn't exit. – solanki... Dec 31 '15 at 16:51
• @Jan even if people don't know the correct concept, they make the correct answer and concept prove wrong. This thing is wrong on stackexchange. – solanki... Dec 31 '15 at 16:55
• My point was: (1) There is exactly one correct systematic IUPAC name per structure. (2) Of course, that does not mean the others are bad or discouraged or allow for misinterpretation. However, you should clearly show that the other name is a non-systematic IUPAC-ish name. (3) I don’t know what you mean with your second comment … – Jan Dec 31 '15 at 17:01