Substances and Nomenclature

The largest part of the subject is the nomenclature of organic compounds, simply because there are so many of them, and of such diverse nature. The types of compounds and stmctures differ considerably among organic, inorganic, and biochemical substances, and each of their respective nomenclatures has developed somewhat differendy, although not independendy. Macromolecular nomenclature and pharmaceutical nomenclature have practical requirements of their own. It is therefore appropriate to treat each of these several areas separately. 

ChemIDplus. Published by the U.S. National Library of Medicine, ChemIDplus [62] is a web-based search system, http //chem.sis.nlm.nih.gov/ chemidplus/, that provides free access to structure and nomenclature authority files used for the identification of chemical substances cited in National Library of Medicine (NLM) databases. ChemIDplus also provides structure searching and direct links to biomedical resources at NLM and on the Internet. The database contains over 349,000 chemical records, over 56,000 of which include chemical structures, and is searchable by name, synonym, CAS registry number, molecular formula, classification code, locator code, and structure. 

The systematic naming of substances and presentation of formulae involve the construction of names and formulae from units that are manipulated in accordance with defined procedures in order to provide information on composition and structure. There are a number of accepted systems for this, of which the principal ones will be discussed below. Whatever the pattern of nomenclature, names and formulae are constructed from units that fall into the following classes ... 

The above is a typical illustration of many confused notions of the ancients due to the fact that they possessed no knowledge of the elementary constituents of substances. The criteria for classification and nomenclature were based upon superficial phenomena, or upon the sources or the applicability of the substances to particular purposes. So long as the. concept prevailed that all substances consisted of variable quantities of the four Aristotelian elements, and that their properties were determined by the proportion of these elements, it was not possible for them to conceive of the possibility of a method of analysis based upon elementary compositions of bodies as understood in modern times. 

The Nomenclature Committee of the International Confederation for Thermal Analysis (ICTA) has defined DSC as a technique in which the difference in energy inputs into a substance and a reference material is measured as a function of temperature whilst the substance and reference material are subjected to a controlled temperature program. Two modes, power compensation DSC and heat flux DSC, can be distinguished depending on the method of measurement used1 . The relationship of these techniques to classical differential thermal analysis (DTA) is discussed by MacKenzie2). 

The following paragraphs introduce some basic areas of organic chemical nomenclature. Further details can be found in Chemical Substances Index Names and Nomenclature of Organe Chemistry listed and end of this entry. 

Aldehydes, acids, and esters have roots for one and two carbons that are usually form- and acet-, rather than meth- and eth-, because these prefixes had been used so long they were grandfathered into the naming system (formaldehyde and acetic acid, rather than methanal and ethanoic acid). Departures from IUPAC nomenclature often occur for very common substances and, fortunately, they rarely can be misunderstood (ethyl alcohol instead of ethanol). 

He contributed to the formulation of a new nomenclature in chemistry, based on his understanding of simple substances and on a clear recognition that certain combinations of simple substances were stable, persevering through a series of reactions. 

In reading Nef s description of these substances and their preparation, it must be borne in mind that the available, naturally occurring D-xylose was at that time called i-xylose. Moreover, Rosanoff s convention for assigning configurational prefixes was then relatively new and was not utilized by Nef. Accordingly, Nef s 1-xylose and 1-arabinose, and d-erythro-, l-threo-, l-erythro-, and d-[Pg.41]

The living and growing science of chemistry requires a nomenclature system that is expansible and mutable. Changes for the sake of conformity in different languages are made slowly and with difficulty. Empirical names are suitable for only the simplest substances and more descriptive nomenclature is needed. The expansion of knowledge of the nature of compounds, such as crystalline structures, leads to extension and perfection of the nomenclature system. 

Commission de nomenclature de chimie biologique. This includes rules for the nomenclature of natural amino acids and related substances (in English) (these will no doubt, when completed, supersede 10 above) and Nomenclature de vitamines (in French). 10 cents. 

CAS = Chemical Abstracts Services DOT/UN/NA/IMCO = Department of Transportation/United Nations/North America/International Maritime Dangerous Goods Code EPA = Environmental Protection Agency HSDB = Hazardous Substances Data Bank NCI = National Cancer Institute NIOSH = National Institute for Occupational Safety and Health OHM/TADS = Oi1 and Hazardous Materials/Technical Assistance Data System RTECS = Registry of Toxic Effects of Chemicals Substances SANSS = Structure and Nomenclature Search System... 

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