Reaction, extent order

The glycolysis of PETP was studied in a batch reactor at 265C. The reaction extent in the initial period was determined as a function of reaction time using a thermogravimetric technique. The rate data were shown to fit a second order kinetic model at small reaction times. An initial glycolysis rate was calculated from the model and was found to be over four times greater than the initial rate of hydrolysis under the same reaction conditions. 4 refs. 

In order indicate the contribution of each reaction to the overall model more clearly, the matrix of reaction extents is differenced, giving the reaction extents in each interval ... 

This order of reactivity was observ for add dedeuteration, but for acetylation, formylation, and chlorination it was slightly different thieno[3,2-h]thiophene (2) > thieno[2,3-h]thiophene (1) > thiophene thieno[3,4-6]thiophene (3) was not studied. A substantially greater discrepancy between theoretical and experimental data was observed for nucleophilic substitution from the data on base dedeuteration and competitive metalation reactions/ the order of decreasing reactivity was as follows thieno[2,3-h]thiophene (1) > thieno[3,2-h]thiophene (2) > thiophene. To a certain extent this may be explained by differences in the mechanism of metalation and deuterium exchange with a base. A discrepancy between calculation and experiment was also found for free-radical substitution. ... 

Put another way, epimerization is the mechanistic event, racemization is the observation. True racemization, the actual production of a racemic mixture, is rarely seen in peptide synthesis. Instead, it is the extent of epimerization that defines the stereochemical outcome of a peptide-bond-forming reaction. In order to assess the probability of epimerization under a given set of conditions, one must be aware of the mechanisms of epimerization, as well as the thermodynamic and kinetic factors that affect this process. 

The primary purpose of this section has been to show the possibilities for using density and area profile data to aid in the better understanding of gas-carbon reactions. In order to determine specific reaction rates and carbon dioxide concentrations at given penetrations, it has been necessary to make assumptions which can only be approximations to the truth. Several major anomalies in the results have been found, however. The calculated concentrations of carbon dioxide at the external surface of rods reacted at 1200 (Table VI) and 1305° are not in agreement with the known carbon dioxide concentrations. Clearly, more information is required on the variation of Deir with temperature and its variation with porosity produced at different reaction temperatures. It is feasible that at high temperatures, considerable porosity may be produced without increasing Deo to such a marked extent as found at 900°. Another anomaly is the non-uniformity of reaction found at 925°, when it would be expected that the reaction should be in Zone I. The preliminary assumption of a completely interconnecting pore system may not be valid. It should also be noted that neither the value of K in Equation (75) nor the low-temperature activa-... 

The rate of hydrolysis of 3H-phenyl-cocaine in the presence and absence of each monoclonal antibody as a function of substrate concentration was determined. Production of radiolabeled benzoic acid at time points corresponding to < 5% reaction extent provided initial rates. A saturation kinetics and a linear Lineweaver-Burk plot for each artificial enzyme were plotted. The first-order rate constants (kcat) and Michaelis constants (Km) of selected antibodies are provided in Table 2. 

Extent of involvement varies across VA systems. For example, at the VA clinic in La Jolla, California, a psychiatric pharmacist s scope of practice includes 1) assessing clinical response to medication via mental status exam and psychiatric interviewing techniques 2) assessing development of adverse drug reactions 3) ordering and evaluating appropriate laboratory tests to assess cli-... 

Initial Rate Method For reversible reactions, we use a modified differential method—the initial rate method. In this case, a series of experiments are conducted at selected initial reactant compositions, and each run is terminated at low conversion. From the collected data, we calculate (by numerical differentiation) the reaction rate at the initial conditions. Since the reaction extent is low, the reverse reaction is negligible, and we can readily determine the orders of the forward reaction from the known initial compositions. The rate of the reversible reaction is determined by conducting a series of experiments when the reactor is charged with selected initial product compositions. The initial rate method is also used to determine the rates for complex reactions since it enables us to isolate the effect of different reactants. 

In order to describe the kinetics of enzymatic starch depolymerization, information on reaction rate, reaction extent, and product distribution profiles are required. Traditional end-group analysis can be used to a limited extent in the first two areas, but will not provide information about the last important subject. Hence, SEC profiles can provide sufficient insight into the mechanism of starch degradation. 

The kinetics of curing reaction of PU elastomers is analysed by in situ quantitative FTIR. The reactions, uncatalysed and catalysed by dibutyltin dilaurate (DBTDL), follow second-order kinetics at low conversion. At high conversion, however, the second-order rate constants decrease with the increase of reaction extent, due to the influence of diffusion control. The reaction kinetics parameters are given and the possible reaction mechanism is further offered. DBTDL is an effective positive catalyst for the reaction of -NCO with -OH. 8 refs. 

It is to be seen that the heat of reaction measured in solution is the resultant of several heats of reaction. In order to establish the heat of reaction of the equilibrium describing the actual extent of the acid-base interaction AH it would be necessary to know the heats of reaction of the other four steps, which is not always possible. Thus, on the basis of various pieces of indirect information, it is usual to regard one or other interaction as negligible, or to assume that the heats or reaction of certain steps just compensate each other. Such simplifications are permissible in many cases without affecting the overall conclusions. However, if any of the assumptions is incorrect, the entire interpretation of the reaction will be faulty. 

In order to achieve high-molecular mass products in reasonable reaction times, small amounts of externally added strong acids (such as sulfuric acid or / -toluenesulfonic acid) were employed as catalysts. Under these conditions, [HA] in Equation 4.1 is the concentration of the catalyst. Making the same assumptions as previously, the dependence of the reaction extent and average degree of polymerization on reaction time are written as 1... 

The variations of the physical and rheological properties of the material with the reaction are described by constitutive equations. In particular, changes in viscosity with reaction extent can encompass several orders of magnitude, so it is important to establish adequate rheoldnetic relationships. 

Alternate Formal Graph The possibility to model a reactive species or a chemical reaction in the physical chemical energy variety is restricted to first-order reactions. Higher-order reactions require another energy variety especially devoted to the modeling of any kind of reaction called chemical reaction energy. The state variables in this energy variety are the reaction extent as basic quantity, the affinity JA as effort, and the reaction rate V as fiow. 

Another energy variety required. The case of reaction orders higher than one cannot be handled with the sole physical chemical energy variety. It requires a supplementary energy variety, called chemical reaction energy, whose state variables are the reaction extent (basic quantity), the affinity (effort), and the reaction rate (flow). This subject is treated as a coupling between energy varieties in case study J1 nth-Order Chemical Reaction in Chapter 12. 

As in any solid-liquid reaction, the reactivity of the carbon precursor is a key factor governing the activation process. Thus, in the case of coals, the lower the rank, the higher the reaction extent with the hydroxide. As the structnral order of the carbon increases (i.e., anthracite versus lignite), the activation process becomes more difficult. In these cases, KOH is much more effective than NaOH, presumably because of its easier intercalation in the graphene layers of the carbon precursors. 

In the past two decades, several papers have appeared on lactide manufacture [73, 74]. A main underlying problem in understanding all information is that the reaction from oligomer to lactide is an equilibrium reaction. In order to pull the reaction toward the right, lactide must be withdrawn from the system. In reaction engineering terms, this means that the chemical kinetics of the reaction cannot be understood without consideration of the method and efficiency of lactide removal. In terms of know-how described in patents, this means that reported lactide production rates depend to a large extent on the geometry of the equipment in which lactide synthesis is performed and that provides for removal of lactide vapor from the reaction zone. 

The two-step preparation via an intermediate (HBPAA or LPAA) was chosen for the preparation both HBPI (Figure 9) and LPI [5]. Taking into consideration the gel (crosslinked structure) formation at definite reaction extent during the reaction of a bifunctional and a trifunctional monomer [15], our attention was also devoted to the choice of optimal reaction conditions of the HBPI(ODPA-MTA) preparation. The maximal monomer concentrations in NMP and the way of their combination were especially found. The dianhydride solution was added drop-to-drop to the diamine solution. This monomer order also decreases a probability of the dianhydride hydrolysis during an intermediate preparation. 

This equivalence also holds for predicting chemical conversion as can be seen in Fig. 12 where reaction extent was calculated for a second order reaction with unmixed feedstreams. The agreement is excellent. More generally, equivalence relationships can be established between all one-parameter micromixing models. For instance, the various models cited above yield approximately the same results under the equivalence conditions ... 

We have an ambitious goal to classify catalytic oxides known to be selective in different oxidation reactions, in order to further use the resulting classification as a predictive trend. Among the parameters mentioned earlier, optical basicity A as well as ICP seemed to be the most appropriate parameters, because both take into account not only the type (ionic to covalent) of Me-O bond but also the extent (through polarizability) of the negative charge borne by oxygen. Duffy et al. 

Equation (1-6) provides a unique estimate of reaction yields because the first-order reaction extent depends only on the time that the molecule has spent in the system and not on interactions or mixing with other molecules. Reactions other than first order give more ambiguous results because the RTD does not measure spatial mixing between molecules that can affect reaction yields. 

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