E factor calculation

The ratio of the content of a fatty acid in position 2 of the triacylglycerides to its total content (E factor, E = enrichment) is independent of the origin of the plant oil. After hydrolysis of the fat with pancreatic lipase, separation of the 2-monoglycerides, and their methanolysis, the concentration in position 2 is determined by gas chromatography and the E-factor calculated (examples for linoleic acid are shown in Table 14.25). Adulteration of olive oils with ester oils is shown by an increased E-factor for palmitic acid (cf. 3.3.1.4). 

Quantities of waste produced can be calculated readily by analysing mass outputs using, for example. E-factor calculations. However, this does not give insight into the nature of the waste itself or other life cycle considerations, such as how the waste is disposed of. Problems can arise with mixed... 

In E factor calculations the quantity P, -P represents waste, and for an actual industrial process, the isolated yields must be taken into account. Also, any solvent or any other material loss must be added to P, -P. 

A comparison of these predicted values of E with the measured values plotted in the bar-chart of Fig. 3.5 shows that, for metals and ceramics, the values of E we calculate are about right the bond-stretching idea explains the stiffness of these solids. We can be happy that we can explain the moduli of these classes of solid. But a paradox remains there exists a whole range of polymers and rubbers which have moduli which are lower - by up to a factor of 100- than the lowest we have calculated. Why is this What determines the moduli of these floppy polymers if it is not the springs between the atoms We shall explain this under our next heading. 

Increases in reaction rate with temperature are often found to obey the Arrhenius equation, from which the apparent values of the reaction frequency factor, A, and the activation energy, E, are calculated. The possibility that the kinetic obedience changes with temperature must also be considered. 

The atom economy for this process is 86.5% (100 X 116/134), which is reasonable. To calculate the E-factor and EMY further information is needed. From published literature (Vogel s Practical Organic Chemistry ), a standard procedure is to mix butanol (37 g) with glacial acetic acid (60 g), and a small amount of sulfuric acid catalyst (ignored in all calculations). Following completion of the reaction the mixture is added to water (250 g). The crude ester is washed further with water (100 g), then saturated sodium bicarbonate solution (25 g) and finally water (25 g). After drying over 5 g of anhydrous sodium sulfate the crude ester is distilled to give product (40 g) in a yield of 69%. 

From this further analysis, the actual amount of waste (and its nature) per kilogram of product will become evident. At this stage it is also important to look forward and assess options for recycling or reusing the waste on site for example if a solvent can be efficiently recovered then this should be taken into account in calculating the E-factor. Although the choice of which route to fully optimize may not be obvious even from this further analysis, it will facilitate a reasoned discussion of the issues. 

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. 

Put in another way, the E factor represents the ratio of kilos in to kilos out i.e. it is the mass balance or the weight ratio of all the raw materials, including solvent losses, to the amount of desired product. It can be readily calculated for a particular product line, production site, or even a whole company. It is quite amazing, therefore, that so few... 

Iteration. Matrix correction factors are dependent on the composition of the specimen, which is not known initially. Estimated concentrations are initially used in the correction factor calculations and, having applied the corrections thus obtained the calculations are repeated until convergence is obtained, i.e. when the concentrations do not change significantly between successive calculations. 

Because parts of the model are used in the Dutch pesticide authorization procedure to estimate worker exposure during re-entry, a study was conducted to validate some of the aspects of the proposed model. Emphasis was put on the relationship between hie applied amount of active ingredient and the resulting increase of DFR in relevant zones (crop heights), as well as determining factors (i.e., application techniques and crop density, or leaf volume index). In addition, the influence of re-entry time and crop density on transfer factors (calculated from levels of re-entry exposure and either DFR or SFR) was studied. 

Fig. 7.7. Effects of Poisson photon noise on calculated SE and FRET values. (A) Statistical distribution of number of incoming photons for the mean fluorescence intensities of 5,10, 20, 50, and 100 photons/pixel, respectively. For n = 100 (rightmost curve), the SD is 10 thus the relative coefficient of variation (RCV this is SD/mean) is 10 %. In this case, 95% of observations are between 80 and 120. For example, n — 10 the RCY has increased to 33%. (B) To visualize the spread in s.e. caused by the Poisson distribution of pixel intensities that averaged 100 photons for each A, D, and S (right-most curve), s.e. was calculated repeatedly using a Monte Carlo simulation approach. Realistic correction factors were used (a = 0.0023,/ = 0.59, y = 0.15, <5 = 0.0015) that determine 25% FRET efficiency. Note that spread in s.e. based on a population of pixels with RCY = 10 % amounts to RCV = 60 % for these particular settings Other curves for photon counts decreasing as in (A), the uncertainty further grows and an increasing fraction of calculated s.e. values are actually below zero. (C) Spread in Ed values for photon counts as in (A). Note that whereas the value of the mean remains the same, the spread (RCV) increases to several hundred percent. (D) Spread depends not only on photon counts but also on values of the correction...

There are some ways to evaluate environmental burden in chemical synthetic processes. The atom economy is the fraction of the atoms in the product to the fraction of all atoms in the reactants. The E factor is the ratio of the mass of all waste to the mass of product. For the following reaction concerning the production of propylene oxide, calculate the theoretical atom economy and E factor. 

McNair, L. A., A. G. Russell, M. T. Odnian, B. E. Croes, and L. Kao, Airshed Model Evaluation of Reactivity Adjustment Factors Calculated with the Maximum Incremental Reactivity Scale for Transitional-Low Emission Vehicles, J. Air Waste Manage. Assoc., 44, 900-907 (1994). 

It is a truism that the simplest concepts are often the most effective, and this can be said of Sheldon s E factor [19, 20] which was developed by Sheldon in order to highlight the amount of waste generated to produce 1kg of chemical product across different branches of the chemical industry. The E factor is defined as the mass ratio of waste to product. E factor is now widely quoted across many different chemical industries in many different fora, as Sheldon provided a simple benchmark guide for different sectors of the chemical industry and this has been widely pubhshed and presented in multiple venues. For examples of processes described in this book where E factors have been calculated see Sechons 5.4 and 8.4. 

Mass intensity, as defined by GlaxoSmithKhne (GSK), did not include any process water used in the system as this was one source of confusion in the use of E factor, with some people including water and others not. However, in the original definition, Sheldon generally excluded water from calculation, because... 

From Figure 17 it is apparent that the molecules evaporate by a two-step process. The atoms evaporate to the plane which passes through P and is parallel to the surface. Any atoms which collide with one another can form a molecule. Any molecule thus formed has a high probability of evaporating. Hence to get an expression for the evaporation rate E we calculate the numbers which pass through 1 cm. of this plane in 1 sec. and multiply this by the probability that they will collide with an atom in this plane. The number of atoms per square centimeter in this plane is equal to Na (the number of atoms per square centimeter at the minimum) times the Boltzmann factor where tph/2 is nearly... 

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