Preferred IUPAC name

A preferred IUPAC name (or PIN) is the unique name assigned to a chemical substance from among the possible names generated by IUPAC nomenclature. It is intended for use in legal and regulatory situations.International Union of Pure and Applied Chemistry (2004-10-09). [http://old.iupac.org/reports/provisional/abstract04/favre_310305.html Draft recommendations 2004] .]

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, e.g. toluene, which may also be correctly named as "methylbenzene" or "phenylmethane".

The introduction of preferred IUPAC names provides a set of rules for choosing between these multiple possibilities in situations where it is important to decide on a unique name: e.g. in
*patent specifications;
*customs regulations;
*environmental and occupational safety and health regulations; etc.The wider choice of names remains available for more general contexts, so that tetrahydrofuran remains an unambiguous and acceptable name for the common organic solvant, even if the preferred IUPAC name is "oxolane". [Rules P-53.2.2 and P-63.5, Draft recommendations 2004.]

PIN recommendations

The PIN recommendations for organic compounds were published in draft form in October 2004, and incorporated into the 2005 revision of "Nomenclature of Inorganic Chemistry" [RedBookRef] . As of April 2008, PIN recommendations for inorganic compounds are still under development. [International Union of Pure and Applied Chemistry [http://old.iupac.org/projects/2006/2006-038-1-800.html Project 2006-038-1-800] .] An "organic" compound, for the purposes of preferred IUPAC names, is defined as a compound which
# contains at least one carbon atom; and
# does not have any bonds between carbon and an element from groups 1–12.This has one or two surpising effects, such as the preferred name "formonitrile" for hydrogen cyanide. [Rule P-66.5.1.2, Draft recommendations 2004.]

In general, substitutive nomenclature of used for preferred IUPAC names, e.g. "ethoxyethane" instead of diethyl ether, "tetrachloromethane" instead of carbon tetrachloride. Functional class nomenclature (also known as radicofunctional nomenclature) is used for acid anhydrides, esters, acyl halides and pseudohalides and salts. Other nomenclature systems are also used in particular circumstances.

The number of "retained" non-systematic names of simple organic compounds (e.g. formic acid, acetic acid) has been much reduced 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.

References