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chemical nomenclature A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry (IUPAC). The ...
, a preferred IUPAC name (PIN) is a unique name, assigned to a chemical substance and preferred among the possible names generated by
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
nomenclature. The "preferred IUPAC nomenclature" provides a set of rules for choosing between multiple possibilities in situations where it is important to decide on a unique name. It is intended for use in legal and regulatory situations. Preferred IUPAC names are applicable only for
organic compounds In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...
, to which the IUPAC has the definition as compounds which contain at least a single carbon atom but no
alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of ...
, alkaline earth or transition metals and can be named by the nomenclature of organic compounds (see
below Below may refer to: *Earth * Ground (disambiguation) *Soil *Floor * Bottom (disambiguation) *Less than *Temperatures below freezing *Hell or underworld People with the surname *Ernst von Below (1863–1955), German World War I general *Fred Below ...
). Rules for the remaining organic and inorganic compounds are still under development. The concept of PINs is defined in the introductory chapter (freely accessible) and chapter 5 of the ''"Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013"'', which replace two former publications: the ''"Nomenclature of Organic Chemistry"'', 1979 (the ''Blue Book'') and ''"A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993"''. The full draft version of the PIN recommendations (''"Preferred names in the nomenclature of organic compounds"'', Draft of 7 October 2004) is also available.


Definitions

A preferred IUPAC name or PIN is a name that is preferred among two or more IUPAC names. An IUPAC name is a systematic name that meets the recommended IUPAC rules. IUPAC names include retained names. A general IUPAC name is any IUPAC name that is not a "preferred IUPAC name". A retained name is a traditional or otherwise often used name, usually a trivial name, that may be used in IUPAC nomenclature.IUPAC Provisional Recommendations 2004, par. 10-12
Chapter 1
/ref> Since systematic names often are not human-readable a PIN may be a retained name. Both "PINs" and "retained names" have to be chosen (and established by IUPAC) explicitly, unlike other IUPAC names, which automatically arise from IUPAC nomenclatural rules. Thus, the PIN is sometimes the retained name (e.g., phenol and acetic acid, instead of benzenol and ethanoic acid), while in other cases, the systematic name was chosen over a very common retained name (e.g., propan-2-one, instead of acetone). A preselected name is a preferred name chosen among two or more names for
parent hydride In chemistry, a parent hydride in IUPAC nomenclature refers to a main group compound with the formula , where A is a main group element. The names of parent hydrides end with ''-ane'', analogous with the nomenclature for alkanes. Derivatives of ...
s or other
parent structure In chemistry, a parent structure is the structure of an unadorned ion or molecule from which derivatives can be visualized. Parent structures underpin systematic nomenclature and facilitate classification. Fundamental parent structures have one ...
s that do not contain carbon (inorganic parents). "Preselected names" are used in the nomenclature of organic compounds as the basis for PINs for organic derivatives. They are needed for derivatives of organic compounds that do not contain carbon themselves. A preselected name is not necessarily a PIN in inorganic chemical nomenclature.


Basic principles

The systems of chemical nomenclature developed by the International Union of Pure and Applied Chemistry (IUPAC) have traditionally concentrated on ensuring that chemical names are unambiguous, that is that a name can only refer to one substance. However, a single substance can have more than one acceptable name, like toluene, which may also be correctly named as "methylbenzene" or "phenylmethane". Some alternative names remain available as "retained names" for more general contexts. For example, tetrahydrofuran remains an unambiguous and acceptable name for the common organic solvent, even if the preferred IUPAC name is "oxolane". Substitutive nomenclature (replacement of hydrogen atoms in the parent structure) is used most extensively, for example "ethoxyethane" instead of diethyl ether and "tetrachloromethane" instead of
carbon tetrachloride Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemic ...
. Functional class nomenclature (also known as radicofunctional nomenclature) is used for
acid anhydride An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid. In organic chemistry, organic acid anhydrides contain the functional group R(CO)O(CO)R'. Organic acid anhydrides often form when one equivalent ...
s, esters,
acyl halide In organic chemistry, an acyl halide (also known as an acid halide) is a chemical compound derived from an oxoacid by replacing a hydroxyl group () with a halide group (, where X is a halogen). If the acid is a carboxylic acid (), the compoun ...
s and pseudohalides and salts. Also ''skeletal replacement operations'', ''additive and subtractive operations'' and ''conjunctive operations'' are applied.


Retained IUPAC names

The number of retained non-systematic, trivial names of simple organic compounds (for example formic acid and
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...
) has been reduced considerably for preferred IUPAC names, although a larger set of retained names is available for general nomenclature. The traditional names of simple
monosaccharides Monosaccharides (from Greek '' monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-solu ...
, α-amino acids and many natural products have been retained as preferred IUPAC names; in these cases the systematic names may be very complicated and virtually never used. The name for water itself is a retained IUPAC name.


Scope of the nomenclature for organic compounds

In IUPAC nomenclature, all compounds containing carbon atoms are considered organic compounds. Organic nomenclature only applies to organic compounds containing elements from the Groups 13 through 17.
Organometallic compounds Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and s ...
of the Groups 1 through 12 are not covered by organic nomenclature.IUPAC Provisional Recommendations 2004, P-69.
Organometallic compounds
/ref>


Notes and references

{{Reflist, 2 Chemical nomenclature