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A new benign index (BI) parameter is developed and applied to assess the overall"greenness" of chemical reactions and synthesis plans. Previously described radial pentagon green metrics based solely on material efficiency are extended to include BI which takes into account the following potentials for environmental harm: acidification-basification (ABP), ozone depletion (ODP), global warming (GWP), smog formation (SFP), inhalation toxicity (INHTP), ingestion toxicity (INGTP), inhalation carcinogenicity (INHCP), ingestion carcinogenicity (INGCP), bioconcentration (BCP), abiotic resource depletion (ARDP), cancer potency (CPP), persistence (PER), and endocrine disruption (EDP). As with other material efficiency metrics, the benign index is defined as a fraction between 0 and 1 so that it may be added as another radial axis to produce an overall radial hexagon diagram that can be used to evaluate the"green" merits of any given chemical reaction. The utility of the method is demonstrated for industrial chemical reactions producing diphenyl carbonate (DPC) and phenyl isocyanate (PI) using both phosgene-based and nonphosgene-based chemistries, and for synthesis plans for the industrial production of aniline, phenol, and aspirin. A critical discussion is presented on the limitations of the method with respect to proper decision making in route selection, particularly the availability and reliability of key parameters, and the importance of obtaining experimental data for key parameters rather than relying solely on computational methods. © 2012 American Chemical Society.


After 20 years of green chemistry research, a complete algorithm for the determination of material and synthetic strategy efficiencies for synthesis plans to any chemical target has been achieved. This paper presents the first announcement of a comprehensive database consisting of green metrics calculations for 1060 plans to 220 targets of interest to the chemical industry in the following categories: commodity industrial chemicals, pharmaceuticals, agrichemicals, dyestuffs and colorants, natural products, flavorings, fragrances, and sweeteners, and molecules of theoretical interest. Data mining of the original literature covered the period 1828-2010. A summary of trends in achieving green chemistry strategies is presented, including an unbiased method of ranking plans using a suite of parameters, ring construction strategies, and implications on the development of new kinds of smart structure search databases. The take-home message is that targeted optimization is a multivariable problem that requires synergistic maximization and minimization of key variables. Problems in the reporting of chemical syntheses in scientific journals and patents are discussed as well as setting guidelines for their standardization and normalization. The merits of spreadsheet tools are presented from decision making in route selection all the way to fast and accurate proofreading of the final plan chosen. © 2011 IUPAC.


In this paper we present a standardized protocol for the complete evaluation of greenness of 18 industrial routes to methyl methacrylate (MMA) covering material and energy consumptions and environmental and safety impacts. A methodology for estimating energy consumption for chemical reactions and synthesis plans from published journal and patent literature procedures is fully described. A new energy metric pertaining to enthalpic changes from standard state conditions (298 K, 1 atm) to reaction conditions (Trxn, prxn) for all input materials used in a synthesis plan for the production of 1 mol of product is defined with respect to the heating and evaporation of 1 mol of water from 298 K and 1 atm. Limitations and best practices of running the protocol are discussed. The present study serves as a template for implementing the protocol to the green metrics analysis of high volume industrial chemicals. Results of plan rankings are compared with previous work on inherent safety indexes. Based on these findings, the isobutylene and t-butyl alcohol routes to MMA are found to have the overall greenest attributes among the 18 routes examined. © 2015 American Chemical Society.


Following our previous work on introducing a database of tested chemical examples from Organic Syntheses that can be used as a repository for problem set development in green chemistry courses, in this paper we extend this idea to include over 1300 examples taken from Inorganic Syntheses covering 36 volumes. Examples are sorted according to the following 13 categories: asymmetric syntheses, syntheses involving catalyst preparation, chemoenzymatic reactions, classical resolutions, convergent synthesis plans, kinetic resolutions; multicomponent reactions, multistep linear synthesis plans, natural feedstocks as starting materials, reactions involving product distributions, reactions involving sacrificial reagents, reactions involving nonunity stoichiometric coefficients, and polymerization reactions. In this paper, we highlight the skill of balancing chemical equations as a mandatory prerequisite of green metrics analysis. Through a problem set containing 70 exercises, we selected challenging examples from Inorganic Syntheses to emphasize this point and link it to the understanding of reaction mechanisms. A number of these examples also contain errors or missing information that students are asked to correct. This is yet another good training ground to exercise their skills in problem solving. © 2016 The American Chemical Society and Division of Chemical Education, Inc.


Andraos J.,CareerChem | Ballerini E.,University of Perugia | Vaccaro L.,University of Perugia
Green Chemistry | Year: 2015

In this contribution we have used green metrics analysis to compare the material efficiency, environmental impact, and safety-hazard impact in order to compare flow and batch procedures for azidation of α,β-unsaturated carbonyls. It has been proved that flow protocols possess a greener profile over the corresponding batch procedures based on identical chemistries. In this work the new flow procedure described is very efficient; however, the significant uncertainties in the environmental and safety-hazard impact scores are due to the lack of toxicity, hazard, and occupational exposure data available on trimethylsilyl azide and the resin catalysts used here. The results for the new flow procedure show significant and definite improvements over previously published work with respect to waste minimization/material efficiency and are consistent with satisfying green chemistry principles. The results obtained in this work prove the usefulness of our flow-approach for realizing highly efficient processes featuring minimal waste production. © The Royal Society of Chemistry 2015.


This paper describes in detail the determination of the likelihood that a given generalized chemical reaction may be considered intrinsically "green" based on design strategy. Justification is given for setting threshold constraints on reaction yield and kernel reaction mass efficiency (RME) performances at greater than 80% and greater than 61.8%, respectively, for intrinsically green reactions. These criteria are applied to a survey of 60 named ring-forming multicomponent reactions (MCRs) and 2000+ such reactions reported in the literature from 2003 to 2011. Patterns among various ring construction motifs are discussed. Results show that 5- and 6-membered monocyclic rings are most commonly made by [2+2+1] and [3+2+1] cycloadditions where 57% and 76% of them, respectively, have a 100% chance of being intrinsically green from a design perspective. Similarly, the [4.3.0] and [4.4.0] skeletons are the most common fused bicyclic structures made by MCR strategies where 38% and 59% of them, respectively, have a 100% chance of being intrinsically green. The syntheses of various heterocyclic ring structures made by MCRs have also been surveyed using this new criterion. The application of this probability analysis is also demonstrated for the total synthesis of ring containing scaffold structures of praziquantel and frondosin B, two compounds of pharmaceutical interest made using MCRs. The direction of future research in MCR development is also briefly discussed. © 2013 American Chemical Society.


In this paper, we evaluate seven published algorithms on determining material efficiency green metrics for individual chemical reactions and synthesis plans with respect to their implementation by professional chemists and chemical engineers. Specifically, we compare and contrast calculation outputs, visual displays, and ease of use. For a direct head-to-head comparison of algorithm performances, thereby establishing consistency, all methods are tested on the same set of chemical examples taken from Organic Syntheses and journal articles that first introduced the algorithms in the literature. Misconceptions and misinterpretations of applying materials metrics analysis when making claims of greenness for reactions and synthesis plans are also discussed. © 2016 American Chemical Society.


An overall Safety/Hazard Index (SHI) is introduced and defined in the same way as the previously described benign index (BI) covering various environmental impacts. Following the same themes and symbolism usage found in the Workplace Hazardous Materials Information System (WHMIS) and National Fire Protection Association (NFPA) 704 code, SHI covers the following safety-hazard potentials: corrosive gas (CGP), corrosive liquid/solid (CLP), flammability (FP), oxygen balance (OBP) applied to combustion reactions and oxidation reactions, hydrogen gas generation (HGP), explosive vapour (XVP), explosive strength (XSP), impact sensitivity (ISP), risk phrase (RPP), occupational exposure limit (OELP), maximum allowable concentration (MACP), dermal absorption (DAP), and skin dose (SDP). In addition, reaction temperature hazard (RTHI) and reaction pressure hazard (RPHI) indices are defined with respect to reference ambient reaction conditions of 25 C and 1 atm. All three indices vary in value between 0 and 1 to conform to the formalism of BI and other well-known material efficiency green metrics. The methodology is illustrated using single-step and multistep synthesis plans for aniline, phenol, and phenyl isocyanate. Using the best available data, the overall "greenest" routes for these industrially important commodity chemicals are determined with respect to material efficiency, environmental impact, and safety/hazard impact. Results are conveniently presented using radial polygon diagrams and are compared with a modified Edwards-Lawrence inherent safety index formalism. © 2013 American Chemical Society.


Synthesis plans for the following important industrial commodity chemicals using phosgene and phosgene-free chemistries have been analyzed and compared by green metrics to determine the most material-efficient routes so far developed (number of plans given in parentheses): dimethyl carbonate (DMC) (31), diphenyl carbonate (DPC) (40), diphenylurea (DPU) (23), methyl carbamate (MC) (8), methyl chloroformate (MCF) (6), methyl N-phenylcarbamate (MNPC) (25), methyl phenyl carbonate (MPC) (32), phenyl isocyanate (PI) (19), phenyl chloroformate (PCF) (10), and urea (13). Implications of these results are discussed. © 2011 IUPAC.


Andraos J.,CareerChem | Hent A.,University of Toronto
Journal of Chemical Education | Year: 2015

This paper presents a simplified approach for the application of material efficiency metrics to linear and convergent synthesis plans encountered in organic synthesis courses. Computations are facilitated and automated using intuitively designed Microsoft Excel spreadsheets without invoking abstract mathematical formulas. The merits of this approach include (a) direct application of green chemistry principles to synthesis planning; (b) strongly linking green metrics calculations and synthesis strategy; (c) pinpoint identification of strengths and weaknesses of any synthesis plan's material efficiency performance using effective visual AIDS; (d) in-depth quantitative and qualitative critiquing of synthesis plan performance and strategy; and (e) giving opportunities to students to offer insightful suggestions to improve or "green up" published procedures based on their growing personal database of chemical reactions as they continue their education in chemistry. An extensive database of over 600 examples taken from Organic Syntheses was created as a repository of reliable examples that instructors can draw upon to create meaningful classroom pedagogical exercises and homework problem sets that couple material efficiency green metrics analyses and traditional learning of organic chemistry. © 2015 The American Chemical Society and Division of Chemical Education, Inc.

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