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A forum for members and member organizations to share ideas and concerns. Up for Discussion Send your comments by e-mail to <[email protected]>. both admire a sunset reflected on a lake of water. Is wa- The Use of IUPAC ter ‘water’ on Twin Earth? Is ‘water’ water to Oscar? We will return to this idea below when asking what the con- Names in Glossaries sequences would be of naming an incorrect structure by Doug Templeton that has become embedded in chemical science and in broader human experience. n a series of Glossaries related to terminology In his 1972 Princeton lectures [4], Saul Kripke elabo- in toxicology and published in Pure and Applied rates upon the concept of naming, and poses a thought IChemistry (see commentary [1]), common names experiment that can be referred to as “Is Schmidt of substances were used, accompanied to varying Gödel?”. Most of us may know little of Kurt Gödel, ex- degrees with the systematic IUPAC chemical name. In cept perhaps that he discovered the incompleteness of the most recent Glossary of Terms in Neurotoxicology arithmetic (I think I know what he looked like, because [2], however, it was mandated that all substances I have seen pictures, and I have read some biographi- referred to in the glossary should be accompanied, cal details, but I have no first hand knowledge of Gödel, at some point, by the IUPAC name. While use of and little opinion beyond a well-founded belief that he IUPAC names should be obligatory in original research discovered the incompleteness theorem). Kripke, in his papers, this short article is intended to open debate thought experiment, constructs the fictive scenario that on the necessity of their use in glossaries where Gödel had a friend Schmidt, whose remains and papers the reader is looking for guidance to meaning, and were later found in Vienna, proving he (Schmidt) actual- where perhaps hundreds of substances (some of them ly discovered the theorem and Gödel only published it. very complex natural products with correspondingly Kripke asserts “So since the man who discovered the in- complex names) are included. Is a glossary a guide completeness of arithmetic is in fact Schmidt, we, when to meaning, or a source of definition? Does a formal we talk about ‘Gödel’, are in fact always referring to name, intervening between a physical structure and its Schmidt” but then concludes “… it seems to me we are mention in a glossary entry, advance or obscure the not.” (Ref. [4] p. 84). I may justly be accused of oversim- goal of the reader? plification here, but I think this makes the point nicely that a finite set of attributes, perhaps consisting of only one element and perhaps even independent of the truth What’s in a name? value of its appearance in that set, may help to identify the referent, but may not adequately name it. The title To approach these questions, it might be helpful to look of Kripke’s published Princeton lectures, Naming and at some of the philosophical approaches to naming. Hil- Necessity, raises the question to what extent assigning ary Putnam, in The Meaning of “Meaning” [3], argues a name necessitates the properties, including existence, that objects referred to by what he calls ‘natural-kind of the named entity. This should be borne in mind when terms’ are themselves core to the meaning of such we attempt to draw pairwise correspondences between terms. The terms are fixed by the expert community a supposed structural reality, a formalized identifier, and that deals with them, and thus water is fixed as 2H O by an entity of which we believe we are talking. The glos- chemists. For the name ‘water’, the referent is individu- sarist is more concerned with intensional meaning and ated by its chemical formula, H2O. usage than with naming and extensional description, Putnam then uses a device common in contempo- and so, presumably, are his or her readers. rary analytical philosophy, that of parallel Worlds, to construct a thought experiment that has the naming of The value of IUPAC names water as its subject. Earth and Twin Earth are identical in all respects, except that on Twin Earth ‘water’ has a It is indeed satisfying to be able to translate a structure chemical structure different from H2O, say XnY. Water into words in a systematic way. It lets us communicate and twin-water have similar physicochemical properties through language rather than pictographically. It gives except as revealed through examination on the molec- the student of chemistry a better grasp of the rules of ular level. Oscar and Twin Oscar have identical genet- chemical structure, and so the assigning of an IUPAC ic makeup and histories in their respective worlds, and name to a structure has excellent pedagogical value. I presumably have identical mental states. They both believe that for many substances, and especially those have cells that are sustained in solutions of what they of relatively complex structure, pedagogy becomes the call water, they both drink and bathe in water, and they dominant value of the IUPAC name. And so the question 34 CHEMISTRY International May-August 2016 becomes: When is this formality of assigning an IUPAC without referring to its IUPAC name. name a reasonable requirement? I can think of no in- With further regard to the legal requirement, it is a stance where the IUPAC name is more important than structure, and not a name, that is patented. Drugs such the structure it attempts to name, and indeed the name as sertraline, fentanyl, and haloperidol—even if they go can impart no more information than the structure by different common or generic names in different -ju from which it is derived. Most substances, historically risdictions—are defined by the manufacturers that hold at least, have been given a ‘common’ name before their their patents (and by the physicians that prescribe structure was known. We can only apply IUPAC rules of them) as the structures they are believed to represent, nomenclature to a substance later, when we know its and not by IUPAC names that may be written correct- chemical (molecular) structure—the ‘naming’ process ly (or incorrectly on occasion) according to more than then becomes one of translating structures into words. one convention (see Preferred IUPAC Name, below). As In Putnam’s terms, we might say that adrenaline is indi- Hellwich has put it in these pages, “the thing named by viduated as the correct three-dimensional connectivi- the word remains the same, and many of its other prop- ty of C9H13NO3, and this knowledge comes to us from erties remain uncertain, even if another designation is the realm of the experts in structure determination. But selected”. [5] to the nomenclaturist, the exercise is then one of sys- Confirming that acetaminophen and paracetamol tematizing a way in which C9H13NO3 is best rendered in are one and the same substance by providing an IUPAC words, as 4-[(1R)-1-hydroxy-2-(methylamino)ethyl]ben- name can be helpful in discourse, but does not super- zene-1,2-diol. sede the legal status of the structure. Two more serious arguments have been put for- ward for the use of IUPAC names for all substances in The practical use of glossaries a glossary. It is suggested that they remove ambiguity for the chemist, and that they meet a legal requirement Inclusion of the relatively simple IUPAC name for nor- for which IUPAC’s representatives might be called to ac- adrenaline (see sketch below) is non-intrusive in the count in legal proceedings. Importantly for both objec- text of a glossary, and immediately conveys the infor- tives, the rules of IUPAC nomenclature should provide mation to the chemist that it is a catechol structure clarity in referencing a particular chemical compound. with a primary amine functionality, and that there is Take again the example of adrenaline, known in an optically active center that probably matters. Thus, some parts of the English-speaking world as epineph- while not an essential part of a strict glossary defini- rine. Here, the IUPAC name can serve a useful role in tion (“catecholamine hormone acting as a postgan- disambiguation, and confirm that indeed the names glionic adrenergic mediator at α- and β-adrenergic adrenaline and epinephrine refer to the same substance. receptors” [2] seems sufficient to differentiate nor- But in practice there can be no reasonable doubt what adrenaline from other substances and so inform the adrenaline ‘is’, any more than we doubt that adrenaline reader), this added piece of information—the IUPAC is not tryptophan or that Gödel is not Schmidt. Adrena- name—is interesting and non-distracting. It also serves line was isolated, identified, and synthesized more than to reassure the reader that noradrenaline is identical a century ago; for the better part of a century it has been to the substance also called norepinephrine, and fur- a household name to biochemists, it has permeated thermore to distinguish it from the levorotatory iso- endocrinology and neurophysiology, medical practice mer, 4-[(1S)-2-amino-1-hydroxyethyl]benzene-1,2-diol, has been imbued with it, and ‘adrenaline rush’ is used a synthetic compound, “having greater pressor activ- in common speech, indicating general awareness of its ity than the natural dextrorotatory isomer” [2]. Note, physiological effects. I find it difficult to imagine a sce- however, that while to define ‘noradrenaline’ simply nario where the legal obligations of IUPAC would not be as ‘4-[(1R)-2-amino-1-hydroxyethyl]benzene-1,2-diol’, fulfilled by mentioning adrenaline in a recommendation or more accurately as ‘substance whose structure is Noradrenaline has been known by this name, or alternatively as norepineph- rine, throughout the English-speaking world for more than a century.