Volume 78, Issue 11

Green chemistry occupies a research frontier that is the subject of much current research activity. Although it is not a new branch of chemistry, it demands distinctive thought processes about existing and new chemistry tools, as well as knowledge and creative design of those chemical principles that can contribute toward societal growth whilst protecting the environment and human health. To achieve these ends, it is necessary to create more awareness in the lay public, and to ensure that teachers and students at all levels of education become familiar with the basic concepts and their beneficial outcomes. In this respect, developing countries still have much to do in order to achieve higher levels of awareness of and participation in a greener vision. The IUPAC-sponsored Second International Symposium on Green/Sustainable Chemistry, held in Delhi on 10-13 January 2006, contributed successfully to promoting international awareness of green chemistry. Almost 550 delegates attended from 22 countries and participated in deliberations on recent advances in the trend toward more environmentally friendly practice of chemistry. In addition to a program of 8 plenary lectures and three-way parallel sessions for 31 main and 44 invited lectures by eminent scientists, upcoming doctoral candidates and postdoctoral fellows gave 33 oral presentations on their contributions to future developments in green chemistry. The poster presentations showcased up-to-date research on a range of topics including synthesis of bioactive compounds, green edges of physical chemistry including computational methods, and the use of biomaterials, nanotechnology, biomimetic processes, microwave technology, and ionic liquids, amongst others. The subject of methodological industrialization attracted much interest and served as a source of information and inspiration to representatives from no less than 28 chemical and pharmaceutical companies. The Symposium has contributed to the growing recognition that government, industry, and the academic sector need to cooperate closely, in order to achieve and promote the cause of green chemistry and its beneficial consequences throughout the world. The challenge for the chemistry community is to recognize the need and pursue research that engages environmentally friendly challenges and outcomes. Chemistry provides many of the tools that enable us to understand and influence the environment, and has the potential to be a decisive factor in securing an environmentally acceptable future for humankind. At the practical level, each advance through development of a safe process or a safe product contributes to that future. Much has already been achieved, but a great deal more remains to be done. The publication of this collection of papers, based upon a selection of lectures of the Symposium, provides an overview of some of the chemistry through which clean, eco-friendly, and less wasteful manufacturing processes for sustainable development is increasingly being realized. The International Organizing Committee contributed to shaping the program for this important event in the international calendar of green chemistry activities. Thanks are due to the Local Organizing Committee for the efficiency and excellence of the arrangements and for the gracious hospitality extended to all participants. On behalf of the organizers, I am grateful to those who contributed their research work to this issue and for the support from Dr. John W. Jost, IUPAC Executive Director. M. Kidwai Symposium Chairman

This paper describes various examples of organic reactions carried out in high-temperature water (HTW) that have been performed at the University of Nottingham using either batch-type reactors or continuous-flow systems. Homogeneously and heterogeneously catalyzed partial oxidations of aromatic compounds, in situ hydrogenations, heterocyclic reactions, hydrolysis (HYD), saponification (SAP), and deuteration reactions are presented.

Green chemistry is not an emerging trend, but is already a reality owing to its applications. A large number of case studies are presented here in addition to literature work. The case studies cover new approaches and new experiments, which will articulate the requirement for industrial application of sustainable chemistry.

The introduction of the dimension of green chemistry into the assessment of analytical methods should be a natural development trend in chemistry and should coincide with its general policy. Some of the principles of green chemistry - such as prevention of waste generation; safer solvents and auxiliaries; design for energy efficiency; safer chemistry to minimize the potential of chemical accidents; development of instrumental methods - are directly related to analytical chemistry. Analytical chemistry is considered to be a small-scale activity, but this is not always true in the case of controlling and monitoring laboratories whose number of runs performed is high. This makes an analytical laboratory comparable with the fine chemicals or pharmaceutical industry. The use of instrumental methods instead of wet chemistry, automation, and minimization is a new trend in analytical chemistry, making this branch of chemistry more sustainable. In this study, widespread separation methods are considered and an attempt is made to characterize them against the above-mentioned principles. Special attention is given to capillary electrophoresis (CE), which provides a very good opportunity to improve analytical chemistry by replacing many chromatographic methods that consume large volumes of solvents. The choice of different solvents and micronization in analytical chemistry is also discussed.

The incorporation of porphyrin-substituted nucleosides into tetranucleotides using phosphoramidite chemistry on solid support is reported. Both diphenyl and tetraphenyl porphyrin nucleosides were used as building blocks. This method allows the synthesis of chiral homo- and heteroporphyrinic arrays, where the composition and thus the physical properties of the array can be modulated simply by reprogramming the DNA synthesizer. The porphyrin arrays are initially isolated in the free-base form. Remetallation to give the zinc-porphyrins can be achieved using standard procedures in solution. The UV-vis spectra of the arrays are reproducible by a superposition of the absorbance spectra of the individual porphyrins, indicating an undisturbed electronic ground state of the porphyrins in the arrays. The same is true for the steady-state emission spectra of the homoporphyrinic arrays, which are not influenced by the presence of the nucleotide strand. In the mixed porphyrin arrays, large differences in the excited-state properties compared to an equimolar mixture of the building blocks are observed by means that the emission of the diphenyl porphyrin moiety is quenched to a large extent, and the overall emission is dominated by the tetraphenyl porphyrin. The covalent connection of the porphyrins via the DNA-derived backbone therefore substantially alters the excited-state and energy-transfer properties of mixed porphyrin systems. The circular dichroism (CD) spectra show induced negative cotton effects in the region of the porphyrin B-band absorption, which is due to the attachment of the chromophores to the chiral oligonucleotide backbone. Addition of a complementary tetra-adenosine did not alter any of the spectroscopic properties, neither in chloroform nor in acetonitrile solutions. Therefore, it can be concluded that no duplex is formed, which is corroborated by 1 H NMR spectroscopy.

Allylstannanes with remote heteroatom substituents are transmetallated by tin(IV) halides to give allyltin trihalides which react with aldehydes with useful levels of remote stereocontrol; the use of this chemistry is exemplified by syntheses of several natural products. However, organotin starting materials are toxic and lead to residues which are difficult to remove and to dispose of. Studies are therefore underway to find procedures to carry out these and analogous reactions without the use of organotin reagents. Following mechanistic studies into allylstannane transmetallation, the use of allylsilicon and germanium reagents was investigated, with the allylgermanium reagents being viable alternatives to allylstannanes. In addition, investigations of reactions of allylstannanes mediated by bismuth(III) iodide led to the development of reactions of allyl bromides with aldehydes promoted by the low-valency species formed by treatment of bismuth(III) iodide with zinc powder. These reactions proceed with useful complementary 1,5-stereocontrol.

Kinetic resolution of racemic compounds is a familiar method for the preparation of optically active compounds. However, an inevitable and critical drawback from the point of view of green chemistry is the consequent wastage of half of the starting compound. A catalytic asymmetric synthesis of 5-arylcyclohex-2-enones was developed starting from racemic 5-(trimethylsilyl)cyclohex-2-enone, which overcomes the drawback of kinetic resolution. A chiral amidophosphane- or BINAP-Rh(I)-catalyzed asymmetric conjugate arylation of racemic 5-(trimethylsilyl)cyclohex-2-enone with arylboronic acids in dioxane-water (10:1) afforded trans - and cis -3-aryl-5-(trimethylsilyl)cyclohexanones in reasonably high enantioselectivity. Dehydrosilylation of the product mixture with Cu(II) chloride in dimethylformamide (DMF) gave 5-arylcyclohex-2-enones with up to 93 % ee in high yield. Enantiofacial selectivity with chiral phosphane-Rh(I) overrides the trans- diastereoselectivity that is maintained in the achiral or racemic phosphane-Rh(I)-catalyzed conjugate arylation of 5-(trimethylsilyl)cyclohex-2-enone.

The traditional construction of materials is usually driven by classical synthetic transformations involving the making and breaking of covalent bonds. These processes often require high-energy input and highly reactive and hazardous materials. In natural systems, one typically encounters synthetic control schemes that are based on entropic forces rather than these human-designed enthalpic manipulations. In natural processes, phase changes and triggered mixing are often employed to direct systems toward or away from equilibrium conditions. The recognition of these "natural tendencies" allows one to design processes that have reduced toxicological and environmental impact. Results in noncovalent derivatization (NCD) and bioinspired photopolymers that illustrate this shift toward entropic control are described.

Increasingly, chemists are faced with legislation requiring assessment of hazard and risk associated with the production, use, and disposal of chemicals. In addition, the general public are concerned about the dangers that they hear may result from the widespread use of chemicals. They look to the chemist for explanations and assume that chemists understand such matters. When they discover that chemists are often ignorant of the potential of chemicals to cause harm, their confidence in the profession is lost and chemophobia may result. In 1993, IUPAC agreed on a joint project between the Toxicology Commission and the Committee on Teaching of Chemistry to address the issue of the teaching of toxicology in the chemistry curriculum. Part of the project was a distance learning program, which is available through the Internet and on CD. 1 The program currently consists of seven modules, one of which deals specifically with environmental toxicology. The contents of each unit will be explained as each has some input into environmental matters and green/sustainable chemistry. The program is aimed at teacher and student alike, and each module has self-assessment exercises at the end of the module. Additionally, there is material on health and safety, ethical matters, and a case study of the use of dichlorodiphenyltrichloroethane (DDT).

The latest evaluation of atomic weight determinations and other cognate data has warranted 16 changes for the standard atomic weights of the elements, A r (E), from those published previously in the 2001 Table of Atomic Weights. The revised standard atomic weights are as follows: A r (Al) = 26.981 5386(8), A r (Bi) = 208.980 40(1), A r (Cs) = 132.905 4519(2), A r (Co) = 58.933 195(5), A r (Au) = 196.966 569(4), A r (La) = 138.905 47(7), A r (Mn) = 54.938 045(5), A r (Nd) = 144.242(3), A r (P) = 30.973 762(2), A r (Pt) = 195.084(9), A r (Sm) = 150.36(2), A r (Sc) = 44.955 912(6), A r (Na) = 22.989 769 28(2), A r (Ta) = 180.947 88(2), A r (Tb) = 158.925 35(2), A r (Th) = 232.038 06(2). A recommendation is made that δ 13 C values of all carbon-bearing materials be measured and expressed relative to Vienna Pee Dee Belemnite (VPDB) on a scale normalized by assigning consensus values of -46.6 ‰ to L-SVEC lithium carbonate and +1.95 ‰ to NBS 19 calcium carbonate.

This document defines the terms most commonly encountered in the field of polymers containing ionizable or ionic groups and polymers containing ions. The scope of the document has been limited to organic polymers. Inorganic materials, such as certain phosphates, silicates, etc., which also may be considered ionic polymers, are excluded from the present document. The terms selected are those that are widely used in the field of polymers containing ionizable or ionic groups and polymers containing ions. Only those terms that could be defined without ambiguity are considered. The terms are listed in alphabetical order, and cross-references to definitions given in other documents are provided.

The glossary contains definitions of more than 500 terms frequently used in relation to the chemistry, mode of action, regulation, and use of pesticides. A wide range of disciplines is involved in this field, and the glossary was developed as a step in facilitating communication among researchers, government regulatory authorities, and chemists in associated professional areas. The range of terms relates to pesticide residue analysis, sampling for analysis, good laboratory practice, metabolism, environmental fate, effects on ecosystems, computer simulation models, toxicology, and risk assessment. The number of important, "pesticide-related" terms has more than doubled since 1996, when the first IUPAC glossary of this type was developed, an indication of how this field has become so integrated with many other scientific and regulatory disciplines.

Immunosensitization to metal ions through occupational and environmental exposure has been described in earlier papers from this project. Here we discuss the possible role of cytokine profiling in demonstrating and understanding this phenomenon. The cytokines are a large family of polypeptides exerting autocrine, paracrine, and/or endocrine effects. They include interleukins (ILs), interferons (IFNs), and growth factors. They may be grouped as pro-inflammatory (e.g., IL-1, IL-6, IL-12, IL-18, TNF-α), anti-inflammatory (e.g., IL-10), or those regulating T-helper (TH) cell function. The latter are subdivided into those associated with TH1 (e.g., IL-2, IL-12, IFN-γ, TNF-β) or TH2 (e.g., IL-4, IL-5, IL-13) cell function. Because different types of immune reactions (e.g., immediate reaction vs. delayed-type hypersensitivity) differentially involve TH1 and TH2 cells, measurement of cytokine production in response to metal ions can potentially give insight into underlying immune mechanisms and responses. Examples are given for species of Ni, Cr, Co, Hg, Cd, and Be; and in less detail for species of Fe, Pt, Pd, and Rh. Antibodies are available commercially that allow for the determination of many cytokines, and such measurements are most usefully performed with body fluids, supernatants from stimulated lymphocyte cultures, or lysates of lymphocytes or other biopsied cells. The predominant methods include enzyme-linked immunosorbent assay (ELISA) and flow cytometric measurement of the cytokine, bioassay of its activity in cell culture, and polymerase chain reaction (PCR) assessment of its mRNA level. In practice, levels of individual cytokines are highly variable between individuals, and reliable reference values are generally lacking. Ratios of cytokines are more informative than absolute concentrations, and biological variability in cytokine production dictates that repeated testing is necessary to confirm trends. Determining cytokine profiles is presently of questionable diagnostic utility in individual cases of metal sensitization, but is providing mechanistic insights in a research context.

The 2002 IUPAC evaluation of scientific and technological advances relevant to the operation of the Chemical Weapons Convention (CWC) included a recommendation that greater efforts are required in education and outreach to the worldwide scientific and technical community to increase awareness of the CWC and its benefits. In 2004, the President of IUPAC and the Director-General of the Organisation for the Prohibition of Chemical Weapons (OPCW) agreed on a proposal for a joint project on chemistry education, outreach, and the professional conduct of chemists. This led to a joint IUPAC/OPCW international workshop held in Oxford, UK on 9-12 July 2005 with 27 participants from 18 different countries. This report sets out the background to the workshop, the scope of the presentations and discussions, the outcomes of the workshop, and the recommended steps to further chemical education, outreach, and codes of conduct in regard to the obligations of the CWC.