Chemistry common naming system

The nomenclature (qv) of polyamides is fraught with a variety of systematic, semisystematic, and common naming systems used variously by different sources. In North America the common practice is to call type AB or type AABB polyamides nylon-x or nylon-respectively, where x refers to the number of carbon atoms between the amide nitrogens. For type AABB polyamides, the number of carbon atoms in the diamine is indicated first, followed by the number of carbon atoms in the diacid. For example, the polyamide formed from 6-aminohexanoic acid [60-32-2] is named nylon-6 [25038-54-4], that formed from 1,6-hexanediamine [124-09-4] or hexamethylenediamine and dodecanedioic acid [693-23-2] is called nylon-6,12 [24936-74-1]. In Europe, the common practice is to use the designation "polyamide," often abbreviated PA, instead of "nylon" in the name. Thus, the two examples above become PA-6 and PA-6,12, respectively. PA is the International Union of Pure and AppHed Chemistry (lUPAC) accepted abbreviation for polyamides. 

By emphasizing the importance of quantitative analysis, Lavoisier helped establish chemistry as a science. His work on combustion laid to rest the phlogiston theory and the theory that air is an element. He also explained why hydrogen burned in oxygen to form water, or hydrogen oxide. He later published one of the first chemistry textbooks, which established a common naming system of compounds and elements and helped unify chemistry worldwide. These accomplishments earned Lavoisier the reputation of being the father of chemistry. 

In clinical chemistry however, these systems have not been differentiated as yet. Since the oxidation of an alcohol corresponds to the reduction of a ketose or an aldose, the designations ketose reductase and aldose reductase, respectively, were suggested (H4, W14). In this paper however, the enzyme or enzyme system will be named polyol or sorbitol dehydrogenase (SDH), although the latter expression does not characterize exacdy the enzyme s function in a general biochemical sense. But sorbitol or fructose have been commonly used as substrates in clinical chemical investigations. 

All enzymes are named according to a classification system designed by the Enzyme Commission (EC) of the International Union of Pure and Applied Chemistry (IUPAC) and based on the type of reaction they catalyze. Each enzyme type has a specific, four-integer EC number and a complex, but unambiguous, name that obviates confusion about enzymes catalyzing similar but not identical reactions. In practice, many enzymes are known by a common name, which is usually derived from the name of its principal, specific reactant, with the suffix -ase added. Some common names do not even have -ase appended, but these tend to be enzymes studied and named before systematic classification of enzymes was undertaken. 

Chemical compound entity extraction is a different type of entity extraction. One cannot refer to a complete dictionary or thesaurus of chemical compound names, as there is practically an infinite number of compound names. Systematic names, such as the International Union of Pure and Applied Chemistry (IUPAC) nomenclature system [54], are created from a set of rules that determine the name of a chemical compound based on the chemical structure. As an example we show aspirin, which has the common chemical name acetyl salicylic acid and the IUPAC name 2-acetyloxybenzoic acid. The common names, including aspirin, can be found using a thesaurus-based approach with low levels of ambiguity. The IUPAC name is a systematically determined name that must be tagged in the text using a heuristics-based approach (rules based). In many cases, one will have only the IUPAC name, not a known common name, for a compound. 

Considerable progress is being made in the acceptance of a common international system of reference units within the world scientific community. This system, known as SI from the French name, Systeme International d Unites, has been adopted by many international bodies, including the International Union of Pure and Applied Chemistry. In SI, the reference units for length, mass, and time are the meter, kilogram, and second, with the symbols m, kg, and s, respectively. 

The hazards of chemicals and commodities can be ranked by various systems of commodity classifications. Chemical identity can be established through the International Union of Pure and Applied Chemistry (IUPAC) name, trade name, common name, United Nations/North America (UN/ NA) number, Chemical Abstract Service (CAS) registry number, Registry of Toxic Effects of Chemical Substances (RTECS) number or chemical formula. As an example, acrylonitrile can be identified as follows ... 

In carbon chemistry, the term carbenium for trivalent, sextet, positively charged carbon was derived from carbene, for divalent, sextet, neutral carbon. Because divalent silicon is commonly called silylene, the appropriate term for trivalent, sextet, positively charged silicon is silylenium. The alternative but commonly used term carbocation for all positively charged carbon systems finds analogy in silyl cation (much less often, silico-cation). We will use both these naming systems in this discussion. The term siliconium, like carbonium, denotes the highest valency (pentavalency), as in SiH3. The term silicenium for the trivalent system has been discarded since silylene rather than silicene has been accepted as the appropriate term for the divalent state. 

The official naming convention under REACH is that developed and maintained by lUPAC. The lUPAC system is intended to allow an experienced chemist to name a structure under the system by following a set of rules. In practice, many chemical substances are very complex and application of the rules requires the interpretation of a chemist who is an expert not just in chemistry, but also in lUPAC nomenclature. Some chemicals, for the purpose of the European Inventory of Existing Chemical Substances (EINECS) and REACH, have lUPAC names that are common names rather than names that follow a set of rules. lUPAC publishes new lists of names periodically, and occasionally a common name is replaced by a more formal one. This practice results in multiple names for the same substance, and the most current name is not necessarily the one originally placed onto EINECS. CAS offers a service by which it assigns a CAS name and CASRN for a substance for which one already knows the structure and/or the reactants used in the manufacture of the substance, but there is no direct counterpart to this process to identify a correct lUPAC name. There are indirect means such as by cross-checking against a known CAS name and CASRN, or other information such as the chemical s EINECS number. 

The systematic lUPAC system in its simplest form operates under a few basic principles. Application of these rules results in common names in simple cases that are familiar to students of inorganic and organic chemistry. Eor the purposes of this contribution, our focus will be on organic chemicals. The following is representative of lUPAC rules ... 

The chemistry of the aromatic compounds developed somewhat haphazardly for many years before systematic nomenclature schemes were developed. Some of the common names used earher have acquired historical respectabihty and are used today some have even been incorporated into the modem systematic nomenclature system. 

---