Is saturated with formic acid

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Nomenclature of carboxylic acids

The carboxylic acids have trivial names that often go back to the source of their initial isolation.

Examples: formic acid from ants, acetic acid from vinegar, propionic acid from dairy products (from Greek Per "the first" and from Greekpion "Fat"), butyric acid from (rancid) butter, valeric acid from valerian roots and caproic acid from goat's milk (from Latincaper "Goat") back.

Tab. 1
Designation of carboxylic acids (alkanoic acids): common names and systematic names (in brackets)

Illustration of carboxylic acids

In the systematic IUPAC nomenclature, the name is formed from the root alkan. The carboxy group has the highest priority of all functional groups. The longest chain is chosen as the root name. In addition, however, there is the requirement to select the longest chain with the largest possible number of functional groups as the name stem.

Saturated cyclic carboxylic acids are referred to as cycloalkanecarboxylic acids. When it comes to aromatic substances, they are called benzoic acids. In cyclic compounds, the carbon atom that binds the acidic functional group is the C1 atom.

Tab. 2
Examples of the naming of carboxylic acids according to IUPAC

In the case of aliphatic carboxylic acids, the carbon atom of the functional group is the C1 atom. In the (outdated) trivial nomenclature, on the other hand, the carbon atoms were designated with Greek letters, starting with α for the carbon atom (α-carbon atom) that is connected to the acid group.

Tab. 3
Name of the carbon atoms
systematic nomenclature
Trivial nomenclature

Dicarboxylic acids are referred to as alkanedioic acids according to the IUPAC system - but common names are used. The common names of the dicarboxylic acids also come from the natural origin of the carboxylic acids. For example, succinic acid was discovered in the distillate of amber and fumaric acid is found in earth smoke (Fumaria officinalis), a plant that was burned in historical times to drive away evil spirits (from Latin fumus "Smoke").

Tab. 4
Diacids

Illustration of diacids

Maleic acid is less stable than fumaric acid and rearranges into fumaric acid under the influence of light (see video: isomerization of maleic acid to fumaric acid).

Isomerization of maleic acid to fumaric acid