IUPAC nomenclature is a set of recommendations for naming chemical compounds and for describing chemistry and biochemistry in general. The International Union of Pure and Applied Chemistry (IUPAC) is the international authority on chemical nomenclature and terminology.
History of the Standardisation of Nomenclature In 1787, Louis-Bernard Guyton de Morveau published his nomenclature recommendations in collaboration with fellow French chemists Berthollet, de Fourcroy and Lavoisier. This work however covered only what are now called inorganic compounds. With the expansion of organic chemistry in the 19th century, and a greater understanding of the structure of organic compounds, the need for a more global standardised nomenclature became more prominent. Following a series of meetings, the first of which was established in 1860 by August Kekulé, the Geneva Nomenclature of 1892 was created. Another entity called the International Association of Chemical Societies (IACS) existed, and on 1911, gave vital propositions the new organising body should address. These propositions included:
Nomenclature of inorganic and organic chemistry, Standardization of atomic weights, Standardization of physical constants, Editing tables of properties of matter, Establishing a commission for the review of work, Standardization of the formats of publications, Measures required to prevent repetition of the same pap. The same entity also established a commission in 1913 but its work was interrupted by the start of World War I. In 1919, after the end of the first world war, a group of chemists created the International Union of Pure and Applied Chemistry (IUPAC) with this idea of standardising and expanding nomenclature as well as unionising scientists and strengthening the international trade of science. In 1921 they appointed commissions for nomenclature in organic, inorganic, and biochemistry. In 2019 IUPAC celebrated its 100th anniversary.
Use IUPAC states that, "As one of its major activities, IUPAC develops Recommendations to establish unambiguous, uniform, and consistent nomenclature and terminology for specific scientific fields, usually presented as: glossaries of terms for specific chemical disciplines; definitions of terms relating to a group of properties; nomenclature of chemical compounds and their classes; terminology, symbols, and units in a specific field; classifications and uses of terms in a specific field; and conventions and standards of practice for presenting data in a specific field." Recommendations are published in IUPAC's journal, Pure and Applied Chemistry (PAC), the publicly available IUPAC Standards Online database, IUPAC Color Books, and other publications. PAC journal issues are freely available the year following publication. The two IUPAC bodies that lead nomenclature and terminology efforts are Division VIII – Chemical Nomenclature and Structure Representation and the Interdivisional Committee on Terminology, Nomenclature, and Symbols.
Nomenclature of inorganic chemistry
The International Union of Pure and Applied Chemistry (IUPAC) has established a standardized system for naming inorganic compounds. These rules are published in a series of books collectively known as Nomenclature of Inorganic Chemistry, commonly referred to as the "Red Book.".
Nomenclature of organic chemistry
Substitutive nomenclature
Substitutive nomenclature is the most important and widely used system. It is based on naming a principal functional group, which is added as a prefix or suffix to the name of the carbon skeleton. One of the hydrogen atoms in the carbon skeleton is replaced by the functional group — hence the principle of substitution. When multiple functional groups are present, one is designated as the principal group and is expressed as a suffix. The main group is selected according to a priority list established by IUPAC. The remaining groups are treated as prefixes and are attached to the name of the main carbon chain. The selection of the main carbon chain follows a series of strict rules applied sequentially until a single, definitive chain is determined.
Radicofunctional nomenclature This system is based on naming functional classes as the main group (without suffixes), while the remainder of the molecule is treated as one or more radicals.
Additive nomenclature In additive nomenclature, the name is derived from a parent structure to which one or more atoms have been added. This approach is commonly used for hydrogen addition, indicated by the prefix hydro.
Subtractive nomenclature Subtractive nomenclature is the reverse of additive nomenclature. It uses the name of a parent structure from which one or more atoms have been removed. This system is mainly applied to hydrogen removal, indicated by the prefix dehydro. The complete replacement of all methyl groups on a ring with hydrogen atoms is indicated by the prefix nor. This system is primarily used in the nomenclature of natural products.
Replacement nomenclature Replacement nomenclature allows for the specification of a carbon chain and the positions at which carbon atoms are replaced by other atoms—unlike substitutive nomenclature (described above), which specifies the replacement of hydrogen atoms. According to IUPAC rules, this nomenclature system is permitted “if it allows for a significant simplification” of the systematic name. This is often the case when describing well-defined polyethylene glycols (PEGs).
Typographic rules IUPAC nomenclature is accompanied by typographic conventions. A summary of key rules is provided below.
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