Reaction interval

Benson [499] and Livingstone [500] considered the influence of experimental accuracy on measured rate and temperature coefficients. To measure the rate coefficient to 0.1%, the relative errors in each ctj value must be <0.1% and the reaction interval should be at least 50%. Temperature control to achieve this level of precision must be 0.003% or 0.01 K at 300 K. For temperature control to 1 K, the minimum error in the rate coefficient is 5% and in the activation energy, measured over a 20 K interval, is 10%. No allowance is included in these calculations for additional factors such as self-heating or cooling. 

Figure 1 shows three 29Si NMR spectra from reaction intervals 20 sec - 40 min, 40 min - 100 min and 100 - 160 min. These results are important for kinetic investigations. Some reported chlorosilanols are listed in Table 2. 

Figure 1. 29Si NMR spectra from the reaction intervals Table 2. Known Chlorosilanols...

Compare Eq. 3-229 with 3-224. The decay in monomer concentration depends on the orders of both initiator and activator initial concentrations with no dependence on deactivator concentration and varies with t2/3 under non-steady-state conditions. For steady-state conditions, there are first-order dependencies on initiator and activator and inverse first-order dependence on deactivator and the time dependence is linear. Note that Eq. 3-229 describes the non-steady-state polymerization rate in terms of initial concentrations of initiator and activator. Equation 3-224 describes the steady-state polymerization rate in terms of concentrations at any point in the reaction as long as only short reaction intervals are considered so that concentration changes are small. 

AB, CD and EF Plateaus, Tj Initial Temperature. Tf Final Temperature If- I, Reaction interval. Figure 3.8 A typical TG curve. 

Catalyst (reference) Test reaction Interval of pretreatment, °C. T. A log A... 

For the case S = 0.65 (curves 2) which is very close So we obtain the first-order phase transitions at y = 0.193 and at yj = 0.225 the reaction interval is very narrow. As for the case discussed above we do not have a state where the lattice is completely covered by A. 

At five suitable reaction intervals (e.g., 5, 10, 15, 20, and 25 min), remove 5 ml reaction mixture and transfer each subsample to a separate flask containing titration cocktail prepared in step 1. Swirl contents immediately to stop the reaction. 

Run-mean cooling rate, dT/dt Air-wall temperature difference, AT Reaction interval, Atr... 

We see that the expected accuracy of A a is much lower than the errors of measurement and that this arises principally because of the small reaction interval chosen. 

The total mass of major cations transferred to solution during reaction interval, i, is ... 

Highly reactive intermediates, such as atoms and free radicals, occur at small concentrations in many reaction systems. Their net rates of production, Rj, are normally small relative to their total rates of formation and consumption, except for small regions near the start and end of the reaction interval of space or time. This behavior prompted the assumption... 

The effect of an increase in pressure on the TG curve has been described by Brown et al. (28). High-pressure effects would be the opposite of those encountered in low-pressure atmospheres the for the reaction would be shifted to higher temperatures as well as the increase in the reaction interval,... 

The effect of the self-generated atmosphere, curve B, is to increase the initial mass-loss temperature, 7J, and to decrease the reaction interval, Tf — T. The increase in % has the beneficial effect of eliminating the initial mass-loss at room temperature with its resulting uncertainty about the starting point of the curve. The inflection point during loss of water is located at about 135°C and a mass fraction of 0.9. The second stage of mass-loss... 

The reaction interval will be narrower, overlapping reactions will be more clearly resolved, and intermediates will be more accurately identified. 

It has been claimed that irreversible decompositions will show better resolution and a smaller reaction interval in some instances, although it is not known why. 

The reaction interval is the temperature difference between 7 and T as defined previously. 

Since the reagent reacts with primary amines rapidly at room temperature to form fluorescent compounds with different stabilities, the derivatised sample should be injected after a precisely determined reaction interval (usually 2 min), thus limiting the apparatus in its present form to manual operation. 

With these possibilities in mind we attempted the photo-oxygenation of norbornene. With either methylene blue or hematoporphyrin as sensitizer and methanol or pyridine as solvent, we obtained no evidence of any reaction by infrared or NMR spectrum, by gas chromatography, or by spot test for hydroperoxide (potassium iodide/starch in 2-propanol/ acetic acid) or peroxide (hydriodic acid/starch in 2-propanol). While the half-life of reaction of cyclohexene was only about one day under our reaction conditions, no evidence of reaction of norbornene was obtained in a period of one month. Assay of norbornene by gas chromatography with benzene as internal standard failed to show any depletion of norbornene over the attempted reaction interval. 

The total helium flow (850 cc/min.) plus the vapor phase reactant and products maintained the bed in vigorous motion which, in turn, insured good temperature control. Runs were carried out at 1 WHSV based on the low EHI feed component, 410 C and atmospheric pressure. The catalyst was automatically oxidatively regenerated after each 10-20 minutes reaction interval. 

Table 11 Model compound conversion data 410 C, 1 atm., 1.0-1.1 WHSV, 20 min. reaction intervals HZSM-5 in Si02/Al203...

The increase in cellulose II character and decrease in accessibility of the amorphous hydrocellulose upon exposure to the alkaline medium and during the reaction interval definitely indicate partial recrystallization. However, selective removal of amorphous cellulose may have occurred simultaneously. This additional possibility is consistent with the alkaline reaction data. 

Clinical reaction Interval between penicillin Main symptoms administration and symptoms Antibodies involved Specificity ... 

For structure 2, three distinct reaction intervals are needed, two of which are fed-batch operations. The cycle is initiated with a constant a interval, followed by a nonconstant a interval, and completed with a period of standard batch reaction. This is given in Figure 7.5(b) by the path ADBC. 

Figure 15-8. Specific surface area of the siloxene samples oxidized in water (o) and a 2% H2O2 solution ( ) as a function of the reaction intervals.

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