Percentage yield, calculation

The guidance document requires calculation of actual yields and percentages of expected yields. The yield should be recorded at the conclusion of each phase of manufacturing of an API. The expected yield and ranges are established during process validation or from a pilot-scale production run [66]. 

To calculate percentage yield, one needs to know the theoretical value that can be obtained, based on material balance, and if 100% of the reactant(s) is converted to product. After obtaining the experimental value (actual yield), divide it by the theoretical value, then multiply by 100 to get percentage yield.8... 

The theoretical yield of a reaction is the maximum quantity (amount, mass, or volume) of product that can be obtained from a given quantity of reactant. The quantities of products calculated from a given mass of reactant in Section L were all theoretical yields. The percentage yield is the fraction of the theoretical yield actually produced, expressed as a percentage ... 

EXAMPLE M.3 Calculating percentage yield from a limiting reactant... 

Actual yield and percentage of theoretical yield should be determined at the completion of each appropriate phase of manufacturing, processing, packaging, or holding. These calculations should be performed by one person and independently verified by a second individual. 

Finally, when working in the field of asymmetric synthesis, the organic chemist needs to quote both the chemical yield and the optical yield. The percentage optical yield or optical purity [enantiomeric excess (ee) %], is calculated thus ... 

By the approximate rule, the answer should be 1.1 (two significant figures). However, a difference of 1 in the last place of 9.3 (9.3 0.1) results in an error of about 1 percent, while a difference of 1 in the last place of 1.1 (1.1 0.1) yields an error of roughly 10 percent. Thus the answer 1.1 is of much lower percentage accuracy than 9.3. Hence in this case the answer should be 1.06, since a difference of 1 in the last place of the least exact factor used in the calculation (9.3) yields a percentage of error about the same (about 1 percent) as a difference of 1 in thelastplaceof 1.06 (1.06 0.01). Similarly, 0.92 x 1.13 = 1.04. 

For the alkali-catalyzed transesterification reaction of rapeseed oil, we investigated several operating conditions reaction temperature, type and amount of catalyst, molar ratio of methanol to oil, and reaction time. In alkali-catalyzed transesterification, the amount of free fatty acid was assumed to be below 0.5% on the basis of oil weight, in order to obtain high conversion yield (13). The conversion yield or percentage of conversion was calculated by dividing the amount of product by the maximum theoretical product. Because it has a high acid value, the activity of catalyst was diminished in the transesterification reaction. As reported in Table 1, the fatty acid content of rapeseed oil used for this experiment was 0.018%, which was lower than the proposed value (below 0.5%). 

The student calculated the percentage yield and percentage of each component as follows ... 

In section 7.1, you looked at the reaction of hydrogen and nitrogen to produce ammonia. You assumed that all the nitrogen and hydrogen reacted. Under certain conditions of temperature and pressure, this is a reasonable assumption. When ammonia is produced industrially, however, temperature and pressure are manipulated to maximize the speed of production. Under these conditions, the actual yield is much less than the theoretical yield. Examine the next Sample Problem to learn how to calculate percentage yield. 

Yield calculations are not only required according to 21 CFR Part 211.103, but they also provide some measure of process, phase, or step consistency when compared on a batch-by-batch basis. This information may prove useful when continuing process development, process optimization, or in the investigation of any process problems encountered during clinical supply production. Actual yields and percentages of theoretical yield also one of many important measures used to evaluate the validation of a manufacturing process. 

The percentage 3deld cannot be calculated with precision, since the exact quantity of nitro compound in the mixture taken for the reduction is unknown. The quantity of sodium hydrosulfite dihydrate employed is sufficient for the reduction of only 0.133 mole of nitro compound the weight of the purified amino compound corresponds to about 80% of the theoretical yield calculated on the assumption that the hydrosulfite is the limiting reagent. 

This means that 84.8 percent of the possible yield of ammonia was obtained from the reaction. Calculating percentage yield is similar to calculating a baseball player s batting average, as shown in Figure 12.9. 

By assuming (i) that only the above reactions take place, plus the chemical absorption of CO2, (ii) that natural gas consists Just of CH4, (iii) that air consists of 0.80 mole fraction N2 and 0.20 mole fraction O2, and (iv) that the ratio of conversion of CH4 by processes (/) and (2) is controlled through admitting oxygen for reaction (2) by adding just enough air so that the mole ratio of N2 to H2 is exactly 1 3, consider the overall efficiency of a process in which 1 200 m (S.T.P.) of natural gas yields 1.00 metric ton of NH3. (a) How many moles of NH3 would be formed from each mole of natural gas if there were complete conversion of the natural gas subject to the stated assumptions (6) What percentage of the maximum yield calculated in (a) is the actual yield ... 

Table 5. Comparison of TOC removal yields in percentage (calculated orUV estimated) for different refinery treatment plants (site E has been studied several times)...

Calculation of the theoretical yield and percentage yield can be illustrated using hypothetical data for the isopentyl acetate preparation ... 

Use the mole concept to do percentage-yield calculations. (Section 5.11)... 

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