Yield calculations

Figura 1 Calculated K X-ray production cross sections for protons using the tabulated ECPSSR Ionization cross sections of Cohen end Harrigan, and the fluorescence yields calculated es In Johansson et al. (1 barn h IIT cm l.

By using sodium amide in ammonia, ethynyl-Ai-methylpyrazoles 15a-c were synthesized by dehydrohalogenation of dichlorides 13a-c, 14a-c in 60-85 % yields, calculated on acetylpyrazoles 12a-c (Table VTT). 

A variation of the general method for the synthesis of 2-amino-selenazoles is to avoid the use of the free a-halogenocarbonyl compound and in its place react the corresponding ketone and iodine with selenourea.This procedure is also taken from thiazole chemistry. By contrast with thiourea, the reaction with selenourea needs a longer reaction time and the work up of the reaction mixture is somewhat more difficult. Usually an excess of the ketone is used. In the preparation of 2-amino-4-( n-nitrophenyl)selenazole, a very high yield, calculated on the amount of iodine used, was obtained. To explain this peculiar result, the oxidative action of the nitro group was invoked. This liberates free iodine from some of the hydrogen iodide eliminated in the condensation reaction, and the free iodine then re-enters into the reaction. 

Yield (calculated on dry msteriali h2l per cent. ao -b 1° O acid unmber 7 3 eater number 242-4 ester oumber after iicelyfatioD 27U-3 soinble in I and more i-clume 80 per cent, alcohol. 

The collected ethereal filtrates were acidified with 50 ml of 4 N hydrochloric acid and tills solution was stirred vigorously. The hydrochloride of 1-(4 -benzyloxyphenyl)-2-(1 -methyl-2-phenoxy-ethylamino)propanone-1 precipitated out, was filtered off, washed with water and then with diethyl ether. Then this substance was dried in vacuo. The yield was 37.7 g, i.e., 89% of the theoretically possible yield, calculated on 1-(4 -benzyloxyphenyl)-2-bromine propanone-1. This substance had a light yellow color and melted at 197° to 198°C, while decomposing. 

A solution of 35.4 g of 1 -bromohexanone-5 in 200 ml of ethanol was gradually mixed at the reflux temperature with vigorous stirring with 39.7 g of theobromine-sodium in 100 ml of water. After 3 hours reflux the unreacted theobromine was filtered off with suction, the fil-trete was evaporated to dryness, the residue was dissolved in water and the solution was extracted with chloroform. The chloroform was distilled off and 1-(5 -oxohexyl)-3,7-dimethyl-xanthine was obtained as residue after recrystellization from isopropanol, it melted at 102°C to 103°C (about 25% yield, calculated on the reacted theobromine). 

Recrystallization of this product from dichloromethane-ether (1 4) affords needles of 3-(2-piperidino-1-hydroxyethyl)-5-phenylisoxazole (701 mg, 51.3% as an overall yield calculated based on the starting material, melting point 104°C to 106°C. The product thus obtained may be reacted with citric acid to give the citrate. 

Further, in parameter selection, it is recommended to choose the feature empty syringe before filling with next sample to avoid mixing with the rinsing solvent when the sample is withdrawn from the syringe. Small instrument details incorrectly chosen can falsify the yield calculated later on, or result in loss of costly sample. For application of the whole sample volume, i.e., to minimize the vial dead volume, the needle can be adjusted closer to the bottom of the vial, but special care should be taken with that parameter because wrong adjustment may destroy the needle. 

The percent yield calculated in this way corresponds to the amount of product X relative to all products and is not the same as the percent of the starting material converted to X (this latter expression is given by x/a/Co, where C0 is the number of moles of reactant). It should be noted that similar to the relationship between rate and efficiency, a low quantum yield for a photochemical reaction does not necessarily mean that it will be formed in a low yield (the converse is true, however). If, for example, x = 0.005 and 2, t = 0.00005, then... 

Figure 2. Solubilities and molecular weights of a vitrinite (80.8% C, daf) after nonreductive ethylation (yields calculated on ethylated product (daf))...

Paulonis, M. A., and Krishnagopalan, A., Kappa Number and Overall Yield Calculation Based on Digester Liquor Analysis, Tappi J., 71(11) 185 (1988)... 

In this chapter we will consider the following as examples of radiation chemical applications (1) dosimetry, (2) industrial synthesis and processing, (3) irradiation of food, waste, and medical equipment, and (4) low-energy ion interaction with matter. Dosimetry is of fundamental importance for yield calculations and also for personnel exposure. Industrial processing would include... 

The percent yield calculated by using moles or grams would be the same. 

Experimental data from Bech Nielsen s study is shown in Fig. 6 and Fig. 7. The data show that implanted 2H is found predominantly in bond-center sites. This qualitative conclusion can be drawn immediately from the raw channeling data, especially the 111 planar scans, and does not depend on the details of the model used to subsequently analyze the data in greater detail. Si—Si bonds run perpendicularly across the 111 planar channel. At zero tilt, a strong flux peak of planar channeled ions is focused on the bond centered site and causes the peak seen in the data at this angle. However, back-bonded sites are hidden in the wall of this channel, which is unusually thick and consists of two planes of atoms close together. Thus, the ion flux near the back-bonded sites is low when the tilt angle is small, hence the dip in nuclear reaction yield calculated for this site. Bech Nielsen (1988) found that this data pointed to there being a minority of the 2H... 

The simplest way to calculate the energy yield is to multiply the thermodynamic drive by the mass of the limiting reactant, the reactant that will be first exhausted from the fluid as the reaction proceeds. Figure 22.8 shows energy yields calculated in this way, for the various metabolisms considered. An energy yield calculated in this manner is approximate, since the reaction s thermodynamic drive does not... 

Species are given with their proto-solar abundance by mass fraction, after Lodders (2003). The last column gives the yield calculated by Nomoto et al. for core-collapse supemovae within a Salpeter IMF between mass limits of 0.07 and 50 Mq. 

A careful study of assumptions underlying chemical models for the solar neighbourhood and their comparison with observation was carried out by Thomas, Greggio and Bender (1998). They considered nucleosynthetic yields calculated... 

Table 9 Average effective (chemical) heat of combustion and smoke yield calculated from the data measured in the ASTM E 1354 cone calorimeter0...

Return on investment (ROI)—a simple yield calculation without taking into account the time value of money... 

Percent yield. Calculate the percent yield (see Chapter 2, Keeping a Notebook ) and put it on the label. 

Schmitz et al. <2001JP090> developed two group increment schemes for converting HF/6-31G(d) and B3LYP/6-31G(d) calculated energies of aliphatic amines to estimations of heats of formation. Application to the pyrrolizidine yielded calculated values of —1.09 (HF) and —1.02 (B3LYP) instead of — 0.93 kcal mob1 (experimental). 

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