Nomenclature issues

Resolving the nomenclature issues between niche Helds of chemistry... 

Inositol is a deceptively simple molecule. On closer study, a number of sophisticated stereochemical, prochiral, chiral, and conformational issues associated with inositols and their derivatives become evident. Inositols, in particular myo-inositol, play a central role in cellular metabolism. An array of complicated molecules that incorporate the inositol moiety are found in nature. Structural heterogeneity of inositol derivatives is compounded by the presence of stereo- and regioisomers of the inositol unit. Because of the large number of isomeric inositols and their derivatives present in nature, a detailed understanding of the structural, stereochemical, and nomenclature issues involving inositol and its derivatives is essential to investigate biological aspects. A discussion of the stereochemical, conformational, prochiral, chiral, and nomenclature issues associated with inositols and the structural variety of insoitol derivatives is presented in this chapter. 

Owing to the numerous possibilities in which a 1,4-diene can be assembled, especially when heteroatoms are included, a nomenclature issue arises that needs to be addressed from the outset. According to the Hantzsch-Widman nomenclature system in combination with the lUPAC rules, hetera-di-ir-meth-ane reactions are those transformations in which a particular heteroatom replaces the caiixin atom of the 1,4-diene moiety the position is specified by means of a numerical prefix. We will use this suggested nomenclature for the di-Tr-methane photorearrangement as indicated for the substrates shown in Scheme 1. 

In addition, the terms pseudomolecular ion and quasimolecular ion are frequently applied to indicated cationized or anionized molecules. Although the second one is actually recommended by the lUPAC [19], it will not be used in this text. Further information on nomenclature issues can be foimd elsewhere [19-21]. 

Mechanistic possibilities for phosphoryl transfer 51 Nomenclature issues 53... 

Chapter 7 discusses regulation of nanoparticles under REACH and TSCA. Chemical identity/nomenclature issues and risk assessment for nanoparticles are included in this discussion. The book therefore concludes with this new chemical technology that has enormous potential in commercial uses and benefits such as in medical applications, and the potential for harm to humans and the environment due to its unique physical state. EPA and ECHA have commented on how they plan to regulate nanoparticles, and the former has begun to do so, but this is one area where traditional and existing regulatory schemes (and even the science used to determine risk) may be insufficient. 

The scope of the above definition is difficult to comprehend without illustrative examples, a few of which comprise the major contents of this chapter. A few general definitions will lay the groundwork for the more complex nomenclature issues. 

The following section represents a few of the types of nomenclature issues that the EPA has dealt with over the years, the conclusions for which would not be obvious to a chemist in many cases. One is reminded of the adage that the devil is the details, the EPA s details in this case. 

This chapter addresses nomenclature issues involving polymers, including generic definitions of polymers how polymers are named (generally by reactants) how other reactants such as free-radical initiators are considered and how polymers will be treated under REACH along with the confidentiality issues resulting from the need to register monomers and other reactants used to manufacture polymers. 

This chapter discusses the regulatory effect for a substance meeting the polymer definition in these jurisdictions, and a discussion of several special topics the two-percent rule, post-reactions and devolvement of pre-polymers, and nomenclature issues involving epoxy polymers derived from hisphenol-A and epichlorohydrin. We shall also discuss the curious requirement under REACH that monomers and other reactants in reacted form must he registered even though the polymers manufactured from them do not, including consideration of confidential information which may he compromised through this provision. 

Fundamental to the TSCA Inventory is the principle that entries on the Inventory are identified as precisely as possible for the commercial chemical substance, as reported by the submitter. Substances that are chemically indistinguishable, or even identical, may be listed differently on the Inventory, depending on the degree of knowledge that the submitters possess and report about such substances, as well as how submitters intend to represent the chemical identities to the EPA and to customers. Although these chemically indistinguishable substances are named differently on the Inventory, this is not a nomenclature issue, but an issue of substance representation as required by the EPA. Submitters should be aware that their choice for substance representation has an important role in the EPA s determination of how the substance will be listed on the Inventory. 

Under the Toxic Substances Control Act (TSCA), numerous nomenclature issues have arisen over the years, some of which have been discussed in this book. There will undoubtedly be new nomenclature issues to be resolved, nanoparticles being a current case in point. Issues of the past have often arisen out of administrative and sometimes arbitrary naming conventions, but risks associated with chemical substances do not depend on how they are named. Nanoparticles present different issues in the sense that the Environmental Protection Agency (EPA) stated that the TSCA regulates chemical substances of a particular molecular identity, without regard to physical properties such as size and shape. Potential for significant risk due to nanoparticles clearly exists exactly due to those physical properties. Regulators and interpreters of the TSCA must address potential risks such substances may pose even if their non-nano counterparts do not, and even if their newness does not meet the current definition of substances with different molecular identities. 

In the European Union (EU), Registration, Evaluation, Autorisation and Restriction of Chemicals (REACH) resolves the dilemma faced under the TSCA to some degree because there is no distinction between new and existing chemicals. Simultaneously, significant new nomenclature issues will undoubtedly surface. Under the Sixth Amendment to the Dangerous Substances Directive, the European Inventory of Existing Chemical Substances (EINECS) was established as the inventory of chemical substances that were manufactured in or imported into the EU at the time that it was established. EINECS consisted of those chemicals being in commerce in the... 

This book reviews the relevant chemical nomenclature issues in the EU and in the US and their impact on regulatory compliance. In particular, during the pre REACH period, chemical identities frequently were desaibed differently by different manufacturers for the same chemicals. The importance of having consistent nomenclature rules under REACH is related to the establishment of Substance Information Exchange Forums by ECHA after the pre registration process, and, ultimately, industry consortia to meet registration requirements. 

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