Preferred IUPAC name
Encyclopedia
In chemical nomenclature, a preferred IUPAC name (PIN) is a unique name, assigned to a chemical substance and preferred among the possible names generated by IUPAC 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.
Currently, preferred IUPAC names are written only for a great part of the organic compounds (see below). Rules for the remaining organic and inorganic compounds are still under development.
The "Preferred names in the nomenclature of organic compounds" (Draft 7 October 2004) replace two former publications: the "Nomenclature of Organic Chemistry", 1979 (the Blue Book) and "A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993". , these draft recommendations have yet to gain formal approval.
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.
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.
A preselected name is a preferred name chosen among two or more names for parent hydride
s or other parent structure
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.
(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
. Functional class
nomenclature (also known as radicofunctional nomenclature) is used for acid anhydrides, ester
s, acyl halide
s and pseudohalides and salts. Also skeletal replacement operations, additive and subtractive operations and conjunctive operations are applied.
and acetic acid
) 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, α-amino acids and a large number of natural products have been retained as preferred IUPAC names; in these cases the systematic names are very complicated and virtually never used.
Currently, preferred IUPAC names are written only for a great part of the organic compounds (see below). Rules for the remaining organic and inorganic compounds are still under development.
The "Preferred names in the nomenclature of organic compounds" (Draft 7 October 2004) replace two former publications: the "Nomenclature of Organic Chemistry", 1979 (the Blue Book) and "A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993". , these draft recommendations have yet to gain formal approval.
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 nameSystematic name
A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection...
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
Trivial name
In chemistry, a trivial name is a common name or vernacular name; it is a non-systematic name or non-scientific name. That is, the name is not recognised according to the rules of any formal system of nomenclature...
, that may be used in IUPAC nomenclature.
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.
A preselected name is a preferred name chosen among two or more names for parent hydride
Parent hydride
In IUPAC nomenclature, a parent hydride is an unbranched acyclic or cyclic structure to which only hydrogen atoms are attached. Parent hydrides are parent structures that contain one or more hydrogen atoms...
s or other parent structure
Parent structure
In IUPAC nomenclature, a parent structure, parent compound, parent name or simply parent is the denotation for a compound consisting of an unbranched chain of skeletal atoms , or consisting of an unsubstituted monocyclic or polycyclic ring system.Parent structures bearing one or more functional...
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 ChemistryInternational Union of Pure and Applied Chemistry
The International Union of Pure and Applied Chemistry is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Council for Science . The international headquarters of IUPAC is located in Zürich,...
(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
Toluene
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...
, 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
Tetrahydrofuran
Tetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use, however, is as a precursor...
remains an unambiguous and acceptable name for the common organic solvent, even if the preferred IUPAC name is "oxolane".
Substitutive nomenclature
Substitution reaction
In a substitution reaction, a functional group in a particular chemical compound is replaced by another group. In organic chemistry, the electrophilic and nucleophilic substitution reactions are of prime importance...
(replacement of hydrogen atoms in the parent structure) is used most extensively, for example "ethoxyethane" instead of diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
and "tetrachloromethane" instead of carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
. Functional class
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
nomenclature (also known as radicofunctional nomenclature) is used for acid anhydrides, ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s, acyl halide
Acyl halide
An acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group....
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 acidFormic acid
Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...
and acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
) 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, α-amino acids and a large number of natural products have been retained as preferred IUPAC names; in these cases the systematic names are very complicated and virtually never used.