Reaction, greenness efficiency

A Microsoft Excel (Version 5.0 or higher) spreadsheet template form has been developed which allows the calculation of the complete reaction mass efficiency (RME) according to equation (4.1) and raw material cost (RMC) for any chemical transformation. Lines are numbered and line instructions are embedded in the same manner as a personal income tax form. Green metrics are evaluated to determine the greermess of the experiment in a rigorous quantitative way and to determine the bottom line cost of carrying out the experiment. Formula entries are inserted in appropriate cells to facilitate computation. Any... 

Yield and other mass-related metrics such as atom economy, reaction mass efficiency and mass intensity have been examined by Constable et al with regard to their significance concerning greenness and costs. The importance of using a (product) concentration term, which can be mass intensity or mass index, is additionally emphasized by Laird et al This is in compliance with Winterton, who in his twelve more green chemistry principles demands the establishment of full mass balances. 

Quantitative evaluation of chemical processes in terms of environmental impact and eco-friendliness has gradually become a topic of great interest since the original introduction of the atom economy (AE) by Trost [1], and the E-factor by Sheldon [2]. Since then, other indexes have been proposed for the green metrics of chemical processes, such as effective mass yield (EMY) [3], reaction mass efficiency (RME) [4] and mass intensity (MI) [5], along with unification efforts [6, 7] and comparisons among these indexes [8]. 

Because reaction mass efficiency includes all the mass used for a given reaction (whether or not it includes or excludes water), and includes yield, stoichiometry, and atom economy, we believe that this metric is the most helpful metric for chemists to focus their attention on how far from green a given reaction or reaction scheme may be. 

However, the true greenness of this reaction remained far from being ideal, as the necessity to prepare initially the arylboronic acids (or their derivatives) as nucleophilic starting material and to recycle (or to eliminate) the associated waste thereafter violate several of the TPGC. Hence this not only contradicts the concept of atom economy [35], but also increased Sheldon s environmental impact factor E (E = kgwaste/kgproduct) [36]. As a consequence, this resulted in a decrease in the value of the reaction mass efficiency (RME) forthe Suzuki-Miyaura reaction. The value RME = 1 characterizes an absolutely green reaction, but all reactions with RME >0.618,... 

M. K. Patil, M. Keller, B. M. Reddy, P. Pale, J. Sommer, Copper-zeolites as green catalysts for multicomponent reactions an efficient and green synthesis of propargyl amines, Eur. J. Org. Chem., 2008, 26, 4440 445. 

A novel green process for intermolecular hydroarylation of in situ generated o-QMs with electron-rich arenes in aqueous medium under catalyst-free conditions at room temperature has been developed. The reaction is efficient and highly regioselective (Scheme 7.62). 

Joseph, T., S. Sahoo S. B. Halligudi (2005) Bronsted acidic ionic liquids A green, efficient and reusable catalyst system and reaction medium for Fischer esterification. Journal of Molecular CatalysisA Chemical, 234,107-110,ISSN 13811169. 

Saha, D., Saha, A., and Ranu, B. C. (2009). Remarkable influence of substituent in ionic, liquid in control of reaction simple, efficient and hazardous organic solvent free procedure for the synthesis of 2-aryl benzimidazoles promoted by ionic Uquid, [pmim]BF4. Green Chem., 11, 733 737. 

N.J. Parmar, H.A. Barad, B.M. Labana, R. Kant, V.K. Gupta, A glycerol mediated domino reaction an efficient, green synthesis of polyheterocycles incorporating a new thiochromeno[2,3-6]quinoline unit, RSC Adv. 3 (2013) 20719-20725. 

G.A. Choghamarani, P. Zamani, Three component reaction an efficient and green synthesis of 3,4-dihydropyrimidin-2-(H)-ones and thiones using silica gel-supported L-pyrroHdine-2-carboxylic acid-4 hydrogen sulfate. Chin. Chem. Lett. 9 (2013) 804-808. 

In addition to cross-coupling chemistry, one of the most direct routes to the formation of vinyl ethers entails the addition of alcohols and phenols to alkynes. This atom-efficient transformation is referred to as hydroalkoxylation and can be tuned to generate vinyl ethers in excellent yields under very mild conditions. Both intermolecular and intramolecular versions of this reaction are well known, and a vast array of catalysts and conditions has been used for the successful synthesis of vinyl ethers [111, 112]. The following sections will highlight a number of advances in this area with special attention paid to modifications such as the development of fast reactions, green processes, as well as the ability of the reactions to tolerate moisture or air. 

Besides the abovementioned two basic synthetic methodologies, new green chemical synthesis methods such as microthermal, ultrasonic radiation technology, and solvent thermal technology have also been used to prepare ILs to shorten the reaction time and increase the reaction conversion efficiency. 

The number of green metrics subsequently proliferated [20-23]. They can be divided into two types (i) metrics that are a refinement of the AE concept and (ii) metrics that are variations of the E factor (see Figure 1.2). Examples of the former are reaction mass efficiency (RME) and carbon efficiency (CE) introduced by Constable and coworkers [24] at GlaxoSmithKline (GSK). The RME is defined as the mass of... 

Some straightforward, efficient cyclopentanellation procedures were developed recently. Addition of a malonic ester anion to a cyclopropane-1,1-dicarboxylic ester followed by a Dieckmann condensation (S. Danishefsky, 1974) or addition of iJ-ketoester anions to a (l-phenylthiocyclopropyl)phosphonium cation followed by intramolecular Wittig reaction (J.P, Marino. 1975) produced cyclopentanones. Another procedure starts with a (2 + 21-cycloaddition of dichloroketene to alkenes followed by regioselective ring expansion with diazomethane. The resulting 2,2-dichlorocyclopentanones can be converted to a large variety of cyclopentane derivatives (A.E. Greene. 1979 J.-P. Deprds, 1980). 

In a 2-1. round-bottom flask, fitted with an efficient reflux condenser, is placed 500 g. (5.7 moles) of ethyl acetate (Note i), and 50 g. (2.2 moles) of clean sodium wire or finely sliced sodium (Note 2) is added. The reaction is at first quite slow, and must be started by warming on a water bath (Note 3). After the reaction is once started it proceeds vigorously and cooling is then necessary in order to avoid loss of material through the condenser. When the rapid reaction slows down, the reaction mixture is heated on a water bath until the sodium has completely dissolved. This usually requires about one and one-half hours. At this stage the reaction mixture should be a clear red liquid with a green fluorescence. 

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