Chemical nomenclature
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).
IUPAC Nomenclature ensures that each compound (and its various
For example, the main constituent of white vinegar is CH
3COOH, which is commonly called acetic acid and is also its recommended IUPAC name, but its formal, systematic IUPAC name is ethanoic acid.
The IUPAC's rules for naming
Purpose of chemical nomenclature
The main purpose of chemical nomenclature is to disambiguate the spoken or written names of chemical compounds: each name should refer to one compound. Secondarily, each compound should have only one name, although in some cases some alternative names are accepted.
Preferably, the name should also represent the structure or chemistry of a compound. This is achieved by the
The nomenclature used depends on the needs of the user, so no single correct nomenclature exists. Rather, different nomenclatures are appropriate for different circumstances.
A
The IUPAC system is often criticized for failing to distinguish relevant compounds (for example, for differing reactivity of
Differing needs of chemical nomenclature and lexicography
It is generally understood that the purposes of
- resveratrol, a single compound defined clearly by this common name, but that can be confused, popularly, with its cis-isomer,
- omega-3 fatty acids, a reasonably well-defined class of chemical structures that is nevertheless broad as a result of its formal definition, and
- polyphenols, a fairly broad structural class with a formal definition, but where mistranslations and general misuse of the term relative to the formal definition has resulted in serious errors of usage, and so ambiguity in the relationship between structure and activity (SAR).
The rapid pace at which meanings can change on the internet, in particular for chemical compounds with perceived health benefits, ascribed rightly or wrongly, complicate the monosemy of nomenclature (and so access to SAR understanding). Specific examples appear in the
History
The nomenclature of alchemy is descriptive, but does not effectively represent the functions mentioned above. Opinions differ about whether this was deliberate on the part of the early practitioners of alchemy or whether it was a consequence of the particular (and often esoteric) theories according to which they worked. While both explanations are probably valid to some extent, it is remarkable that the first "modern" system of chemical nomenclature appeared at the same time as the distinction (by Lavoisier) between elements and compounds, during the late eighteenth century.
The
who adapted the ideas for the German-speaking world.The recommendations of Guyton were only for what would be known now as inorganic compounds. With the massive expansion of organic chemistry during the mid-nineteenth century and the greater understanding of the structure of organic compounds, the need for a less ad hoc system of nomenclature was felt just as the theoretical basis became available to make this possible. An international conference was convened in Geneva in 1892 by the national chemical societies, from which the first widely accepted proposals for standardization developed.[15]
A commission was established in 1913 by the Council of the International Association of Chemical Societies, but its work was interrupted by World War I. After the war, the task passed to the newly formed International Union of Pure and Applied Chemistry, which first appointed commissions for organic, inorganic, and biochemical nomenclature in 1921 and continues to do so to this day.
Types of nomenclature
Nomenclature has been developed for both organic and inorganic chemistry. There are also designations having to do with structure – see Descriptor (chemistry).
Organic chemistry
- Substitutive name
- Functional class name, also known as a radicofunctional name
- Conjunctive name
- Additive name
- Subtractive name
- Multiplicative name
- Fusion name
- Hantzsch–Widman name
- Replacement name
Inorganic chemistry
Compositional nomenclature
Type-I ionic binary compounds
For type-I
The oxidation state of each element is unambiguous. When these ions combine into a type-I binary compound, their equal-but-opposite charges are neutralized, so the compound's net charge is zero.
Type-II ionic binary compounds
Type-II ionic binary compounds are those in which the cation does not have just one oxidation state. This is common among
An older system – relying on Latin names for the elements – is also sometimes used to name Type-II ionic binary compounds. In this system, the metal (instead of a Roman numeral next to it) has a suffix "-ic" or "-ous" added to it to indicate its oxidation state ("-ous" for lower, "-ic" for higher). For example, the compound FeO contains the Fe2+ cation (which balances out with the O2− anion). Since this oxidation state is lower than the other possibility (Fe3+), this compound is sometimes called
Some ionic compounds contain polyatomic ions, which are charged entities containing two or more covalently bonded types of atoms. It is important to know the names of common polyatomic ions; these include:
- ammonium (NH+4)
- nitrite (NO−2)
- nitrate (NO−3)
- sulfite (SO2−3)
- sulfate (SO2−4)
- hydrogen sulfate (bisulfate) (HSO−4)
- hydroxide (OH−)
- cyanide (CN−)
- phosphate (PO3−4)
- hydrogen phosphate (HPO2−4)
- dihydrogen phosphate (H2PO−4)
- carbonate (CO2−3)
- hydrogen carbonate (bicarbonate) (HCO−3)
- hypochlorite (ClO−)
- chlorite (ClO−2)
- chlorate (ClO−3)
- perchlorate (ClO−4)
- acetate (C2H3O−2)
- permanganate (MnO−4)
- dichromate(Cr2O2−7)
- chromate(CrO2−4)
- peroxide (O2−2)
- superoxide (O−2)
- oxalate (C2O2−4)
- hydrogen oxalate(HC2O−4)
The formula Na2SO3 denotes that the cation is sodium, or Na+, and that the anion is the sulfite ion (SO2−3). Therefore, this compound is named sodium sulfite. If the given formula is Ca(OH)2, it can be seen that OH− is the hydroxide ion. Since the charge on the calcium ion is 2+, it makes sense there must be two OH− ions to balance the charge. Therefore, the name of the compound is calcium hydroxide. If one is asked to write the formula for copper(I) chromate, the Roman numeral indicates that copper ion is Cu+ and one can identify that the compound contains the chromate ion (CrO2−4). Two of the 1+ copper ions are needed to balance the charge of one 2− chromate ion, so the formula is Cu2CrO4.
Type-III binary compounds
Type-III binary compounds are
Substitutive nomenclature
This naming method generally follows established IUPAC organic nomenclature.
Additive nomenclature
This method of naming has been developed principally for coordination compounds although it can be applied more widely. An example of its application is [CoCl(NH3)5]Cl2, pentaamminechloridocobalt(III) chloride.
Ligands, too, have a special naming convention. Whereas chloride becomes the prefix chloro- in substitutive naming, for a ligand it becomes chlorido-.
See also
- Descriptor (chemistry)
- IUPAC nomenclature of inorganic chemistry 2005
- IUPAC nomenclature of organic chemistry
- Preferred IUPAC name
- IUPAC numerical multiplier
- IUPAC nomenclature for organic transformations
- International Chemical Identifier
- List of chemical compounds with unusual names
References
- ISBN 978-0-408-70144-0.
- ISBN 0-632-03488-2.. IUPAC, Chemical Nomenclature and Structure Representation Division (27 October 2004). Nomenclature of Organic Chemistry (Provisional Recommendations). IUPAC.
- .
- .
- ^ Compendium of Chemical Terminology, IMPACT Recommendations (2nd Ed.), Oxford:Blackwell Scientific Publications. (1997)
- ^ Biochemical Nomenclature and Related Documents, London: Portland Press, 1992.
- ISBN 0-86542-6155.
- ^ Compendium of Macromolecular Nomenclature, Oxford: Blackwell Scientific Publications, 1991.
- ISBN 978-0-86542-612-2.
- ^ Guyton de Morveau, L. B. (1782), "Mémoire sur les dénominations chimiques, la necessité d'en perfectionner le système et les règles pour y parvenir", Observations Sur la Physique, 19: 370–382
- Fourcroy, A. F. de (1787), Méthode de Nomenclature Chimique, Paris: Cuchet, archived from the originalon 2011-07-21.
- ^ Lavoisier, A. L. (1801), Traité Élémentaire de Chimie (3e ed.), Paris: Deterville.
- Berzelius, J. J.(1811), "Essai sur la nomenclature chimique", Journal de Physique, 73: 253–286.
- S2CID 98774420.
- ^ "Congrès de nomenclature chimique, Genève 1892", Bulletin de la Société Chimique de Paris, Série 3, 8: xiii–xxiv, 1892.
External links
- Interactive IUPAC Compendium of Chemical Terminology (interactive "Gold Book")
- IUPAC Nomenclature Books Series (list of all IUPAC nomenclature books, and means of accessing them)
- IUPAC Compendium of Chemical Terminology ("Gold Book")
- Quantities, Units and Symbols in Physical Chemistry ("Green Book")
- IUPAC Nomenclature of Organic Chemistry ("Blue Book")
- Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 ("Red Book")
- IUPAC Recommendations on Organic & Biochemical Nomenclature, Symbols, Terminology, etc. (includes IUBMB Recommendations for biochemistry)
- chemicalize.org A free web site/service that extracts IUPAC names from web pages and annotates a "chemicalized" version with structure images. Structures from annotated pages can also be searched.
- ChemAxon Name <> Structure – IUPAC (& traditional) name to structure and structure to IUPAC name software. As used at chemicalize.org
- ACD/Name – Generates IUPAC, INDEX (CAS), InChi, Smiles, etc. for drawn structures in 10 languages and translates names to structures. Also available as batch tool and for Pipeline Pilot. Part of I-Lab 2.0
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- JSTOR 3251756.
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