Yields actual

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 ... 

Figure 3.5. Factorial space. Numbers in circles denote process yields actually measured (initial data set) all other numbers are extrapolated process yields used for planning further experiments (assuming that the repeatability Sy = 0.1 all values are rounded to the nearest integer) the estimated yield of 108% shows that the simple linear model is insufficient.

The feasibility of strategies B and C has been demonstrated particularly for the synthesis of the so-called pericyclinosilanes (previously also named cyclo-silethynes [20]) 70-72 (Fig. 3). Historically, an approach of type C was the first one ever, in that [4]pericyclinosilane 70 was prepared by simple pyrolysis of a mixture of calcium carbide and dichlorodimethylsilane in a molten salt mixture of KCl/NaCl at 400°C, albeit in low yield (actual yield not reported) [21]. A... 

Often the faith in analytical methods gives a false sense of high yields, when the tars or heavy by-products are not part of the quantification. One should always get an in-hand yield, actually isolating a known weight of a pure product from a known amount of starting materials. 

Dehydration of amides.1 Primary amides are converted by this reagent into nitriles at 25° in 82-92% yield. Actually, this reaction occurs more readily than dehydration of a secondary hydroxyl group. 

In a 5-I. round-bottom flask, fitted with a mechanical stirrer and reflux condenser, are mixed 1150 cc. of water, 840 cc. of commercial sulfuric acid and 700 g. of benzyl cyanide (preparation III, p. 9). The mixture is heated under a reflux condenser and stirred for three hours, cooled slightly and then poured into 2 1. of cold water. The mixture should be stirred so that a solid cake is not formed the phenylacetic acid is then filtered off. This crude material should be melted under water and washed by decantation several times with hot water. These washings, on cooling, deposit a small amount of phenylacetic acid which is filtered off and added to the main portion of material. The last of the hot water is poured off from the material while it is still molten and it is then transferred to a 2-1. Claisen distilling flask and distilled in vacuo. A small amount of water comes over first and is rejected about 20 cc., containing an appreciable amount of benzyl cyanide, then distils. This fraction is used in the next run. The distillate boiling i76-i89°/5o mm. is collected separately and solidifies on standing. It is practically pure phenylacetic acid, m. p. 76-76.5° it amounts to 630 g. (77.5 per cent of the theoretical amount). As the fraction which is returned to the second run of material contains a considerable portion of phenylacetic acid, the yield actually amounts to at least 80 per cent. 

The percentage yield is the fraction of the theoretical yield actually produced, expressed as a percentage ... 

The theoretical yield of a product is the maximum mass, amount, or volume that can be expected on the basis of the stoichiometry of a chemical equation. The percentage yield is the percentage of the theoretical yield actually achieved. 

Batch Reconciliation and Label Reconciliation Theoretical Yield Actual Yield Packaged Yield... 

Epoxymethano bridging. Reaction of the bromoketone 1 with LiBr and Li,CO, in DMF at 140° (5, 395) unexpectedly results in the epoxymcthano-bridgcd compound 2 (79% yield). Actually, 2 is obtained in somewhat higher yield when 1 is heated with... 

Epoxidation of a,P-unsaturated acids (1.475). This reaction, first reported in 1959, has seen limited use because of moderate yields. Actually, yields are considerably improved by increasing the amount of catalyst and by increasing the pH to 5.8-6.8. The rate of epoxidation is markedly affected by substitution on the double bond, being enhanced by either an oc-alkyl or a p-c/y-alkyl substituent The rate is also increased by addition of butanediol, lactic acid, or tartaric acid. 

Finally it should be noted that the relative position of the corresponding quasi-Fermi level with respect to the redox potential yields actually the thermodynamic force which drives an electrochemical reaction. This has sometimes been overlooked, and instead it has been assumed that the driving force is simply provided by holes at the upper edge of the valence band or electrons at the lower edge of the conduction band. In view of thermodynamics, this is simply the difference of an electrochemical potential (Fermi level) and an electrical potential. 

Dichlorination of ketones. a-Monochlorination (Clj) of alkyl aryl ketones proceeds readily in a variety of solvents. a.a-Dichlorination has been effected with sodium acetate as catalyst in refluxing acetic acid (5 hours, 80-90% yield). Actually this reaction can be effected with DMF as catalyst and solvent at 80-100° in 35-45 minutes in yields of 80-95%... 

Both values are in excess of ozone yields actually achieved in ozonizers. If we assume that Reaction 9 proceeds at every termolecular collision, we can show that it will be faster than Reaction 2 as long as the ratio O/O2 1/100. 

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