Effective mass yield

Hudlicky et al. [25] were among the first to propose a non-traditional metric in a 1999 paper describing effective mass yield. Effective mass yield was defined as 

This metric is an attempt to define yield in terms of the mass of the product that is made from non-toxic materials. This was one of the first times that reagent and reactant toxicity were included as an important part of determining what is considered to be green, and it is something that was absent from traditional yield measures. Hudlicky et al. did make an attempt to define benign (i.e. those byproducts, reagents, or solvents that have no known environmental risk associated with them, for example, water, low-concentration saline, dilute ethanol, autoclaved cell mass, etc. ), but the explanation suffers from a lack of definitional clarity. 

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Review a recent synthetic reaction you have carried out in the laboratory. Write a balanced equation for the reaction(s) and calculate the atom economy. From your experimental results calculate the Yield, E-factor and Effective Mass Yield (ignoring any water used). Identify ways in which this reaction could be made greener. 

Several other metrics include effective mass yield, atom economy, mass intensity, mass productivity, and reaction mass efficiency, which are defined by Equations 3.2-3.6. 

Effective mass yield is a green metric proposed by Tomas Hudlicky of the University of Florida (Equation 13.7).35... 

Effective mass yield includes actual reagent masses as well as solvents. In effective mass yield, Hudlicky chose to include only nonbenign reagents. Benign reagents include water, dilute saline solutions, and ethanol. The safety of some reagents is debatable, and the subjective nature of effective mass yield calculations is a weakness in the metric. 

Solvents are not included in the calculation. Like effective mass yield, carbon efficiency strives to make a value judgment on the relative importance of various wastes. Elimination of water from a molecule would not count against the carbon efficiency of a reaction, but it would give a decreased atom economy. By not including all wastes, carbon efficiency is not as strict as most green metrics. Of course, all metrics have their shortcomings and carry their own assumptions. 

What is the effective mass yield for the synthesis of 13.f based on the information in question 9 ... 

Other metrics have also been proposed for measuring the environmental acceptability of processes. Hudlicky and coworkers [19], for example, proposed the effective mass yield (EMY), which is defined as the percentage of product of all the materials used in its preparation. As proposed, it does not include so-called environmentally benign compounds, such as NaCl, acetic acid, etc. As we shall see later, this is questionable as the environmental impact of such substances is very volume-dependent. Constable and coworkers of GlaxoSmithKline [20] proposed the use of mass intensity (MI), defined as the total mass used in a process divided by the mass of product, i.e. MI = E factor+1 and the ideal MI is 1 compared with zero for the E factor. These authors also suggest the use of so-called mass productivity which is the reciprocal of the MI and, hence, is effectively the same as EMY. 

This reaction unfortunately requires stoichiometric monoorganotin trihalide and suffers from poor atom economy and effective mass yield. 

There are various other related metrics (i) atom efficiency, (ii) effective mass yield, (iii) carbon efficiency and (iv) reaction mass efficiency ... 

Effective mass yield (EMY) [38] the percentage of the mass of the desired product relative to the mass of all non-benign materials used in its synthesis. However, what is benign it is not defined. 

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]. 

More recently, Tomas Hudlicky5 made the point that the traditionally used metrics of percentage yield and number of steps in a synthesis are too limited and he suggested the use of Effective Mass Yield (EMY). This is defined as ... 

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