Reaction data

Figure A3.6.3. Solvent polarity dependence of the rate constant for the Menshutkin reaction (data from [14]).

RDfile. Tdf Reaction-Data file extension of the MDL Molfile containing one or more sets of reactions nmm.mdli.com 50... 

Compounds are stored in reaction databases as connection tables (CT) in the same manner as in structure databases (see Section 5.11). Additionally, each compound is assigned information on the reaction center and the role of each compound in the specific reaction scheme (educt, product, etc.) (see Chapter 3). In addition to reaction data, the reaction database also includes bibliographic and factual information (solvent, yield, etc.). All these different data types render the integrated databases quite complex. The retrieval software must be able to recall all these different types of information. 

This reaction data set of 626 reactions was used as a training data set to produce a knowledge base. Before this data set is used as input to a neural Kohonen network, each reaction must be coded in the form of a vector characterizing the reaction event. Six physicochemical effects were calculated for each of five bonds at the reaction center of the starting materials by the PETRA (see Section 7.1.4) program system. As shown in Figure 10,3-3 with an example, the physicochemical effects of the two regioisomeric products arc different. 

With its flexible and logical search language, REACCS can retrieve molecular stmctures, the atoms and bonds that are transformed ia a reaction, relative and absolute stereochemistry, the role (reactant, product, solvent, or catalyst) of a molecule ia a reaction, reaction data (eg, temperature and yield), hterature references, and keyword descriptions of reaction types. 

The heal of reaction (see Section 4.4) is defined as tlie enthalpy change of a system undergoing chemical reaction. If the retictants and products are at tlie same temperature and in their standard states, tlie heat of reaction is temied tlie standard lieat of reaction. For engineering purposes, the standard state of a chemical may be taken as tlie pure chemical at I atm pressure. Heat of reaction data for many reactions is available in tlie literature. ... 

The vacuum decomposition [1106] of nickel maleate at 543—583 K was predominantly a deceleratory process. Following an initial surface reaction, data fitted the kinetic expression... 

The photo-induced exo selectivity was observed in other classic Diels-Alder reactions. Data relating to some exo adducts obtained by reacting cyclopentadiene or cyclohexadiene with 2-methyl-1,4-benzoquinone, 5-hydroxynaphtho-quinone, 4-cyclopentene-l,3-dione and maleic anhydride are given in Scheme 4.13. The presence and amount of EtsN plays a decisive role in reversing the endo selectivity. The possibility that the prevalence of exo adduct is due to isomerization of endo adduct under photolytic conditions was rejected by control experiments, at least for less reactive dienophiles. 

With this relationship for all samples was calculated from ninh This M is used for evaluating the reaction data. The ultracen rifuge (u.c measurements were carried out in a Spinco model E analytical ultracentrifuge, with 0.4% solutions in 90% formic acid containing 2.3 M KCl. By means of the sedimenta- ion diffusion equilibrium method of Scholte (13) we determine M, M and M. The buoyancy factor (1- vd = -0.086) necessary for tSe calculation of these molecular weights from ultracentrifugation data was measured by means of a PEER DMA/50 digital density meter. 

The evaluation of the 220 C reaction data show (fig. 2) that the reaction does not follow third order kinetics, sra g. 

In order to determine wether the speed of reaction is limited by the diffusion of the condensate, the following rate diffusion function for sperical particles (6 14) was applied on the reaction data for several partical sizes... 

Use of thermal stability tests (DTA s) to determine the heat sensitivity of a given process mixture is desirable. Recent advances in analytical methods permit good calorimetric determination of heat of reaction. Heat of reaction data are critical for exothermic reactor vent sizing. Heat impact from fire is usually small in comparison, but should not be neglected. 

FIGURE 7.2 Experiment versus fitted batch reaction data (a) first-order fit (b) second-order fit (c) 1.53-order fit. 

Unsteady reaction data are often an excellent means for estimating physical parameters that would be difficult or impossible to elucidate from steady-state measurements. However, the associated problems in nonlinear optimization can be formidable. A recent review and comparison of methods is given by... 

Reactions of the complexes [CjH5Fe(CO)3, (CNCH3)JPF6 [x=l, 2 143), 3 146)] with pentafluorophenyllithium have been carried out. For the mono- and diisocyanide complexes, several products were observed the overall yield was generally low however. These reaction data are summarized by the equations below. 

Equation (1) consists of various resistance terms. l/Kj a is the gas absorption resistance, while 1/ K,a corresponds to the maleic anhydride diffusion resistance and l/i k represents the chemical reaction resistance. The reaction rate data obtained under the reaction conditions of 250°C and 70 atm were plotted according to equation (1). Although catalytic reaction data with respect to time on stream were not shown here, a linear correlation between reaction rate data and catalyst loading was observed as shown in Fig. 2. The gas absorption resistance (1/ a) was -1.26 h, while the combined reaction-diffusion resistance (lJK,a + 1 T]k) was determined to be 5.57 h. The small negative value of gas absorption resistance indicates that the gas-liquid diffusion resistance was very small and had several orders of magnitude less than the chanical reaction resistance, as similarly observed for the isobutene hydration over Amberlyst-15 in a slurry reactor [6]. This indicates that absorption of malei c anhydride in solvent was a rapid process compared to the reaction rate on the catalyst surface. 

Figure 13. Specific 2-CP (open symbols) and 2,4-DCP (solid symbols) hydrodechlorination rate constant K) as a function of the average Ni particle diameter ( nO for reaction over Ni catalysts prepared via impregnation with nitrate (0,0), deposition-precipitation (A,A) and impregnation with nickel ethanediamine ( , ) r= 423K reaction data refer to aqueous solutions. (Reprinted from Reference [147], 2003, with permission from Royal Society of Chemistry).

In order to illustrate how the mode of operation can positively modify selectivity for a large reactor of poor heat-transfer characteristics, simulations of the reactions specified in Example 5.3.1.4 carried out in a semibatch reactor were performed. The reaction data and process conditions are essentially the same as those for the batch reactor, except that the initial concentration of A was decreased to cao = 0.46 mol litre, and the remaining amount of A is dosed (1) either for the whole reaction time of 1.5 h with a rate of 0.1 mol m s", or (2) starting after 0.5 h with a rate of 0.15 mol m " s". It is assumed that the volume of the reaction mixture and its physical properties do not change during dosing. The results of these simulations are shown in Fig. 5.3-15. The results of calculation for reactors of both types are summarized in Table 5.3-3. 

The chemical reaction data are the same as in the preceding example. The reaction kinetics are... 

Reactan Structure mmol H2CO / g catalysf Reaction Data ... 

The datum temperature in the program is 25°C (298 K), which is standard for most heat of reaction data. Specific heats are represented by a cubic equation in temperature ... 

Table 2 Reaction data obtained on hydrogenation of DMIT over AHC-1 with multiple re-use of the catalyst at different TON s.

It is necessary to get the reaction data at lower temperatures (i.e. 350-400 0) to distinguish between... 

The first-stage effluent temperature has been limited to 560 °C in order to prevent excessive catalyst activity losses. The heat of reaction data is slightly inconsistent with the reported activation energies, but use of this expression demonstrates the ease with which temperature dependent properties may be incorporated in the one-dimensional model. 

There is considerable variation in the heat of reaction data employed in different articles in the literature that deals with this reaction. Cited values differ by more than an order of magnitude. If we utilize heat of combustion data for naphthalene and phthalic anhydride and correct for the fact that water will be a gas instead of a liquid at the conditions of interest, we find that for the first reaction (equation 13.2.3) the standard enthalpy change will be approximately — 429 kcal/g mole for the second reaction it will be approximately — 760 kcal/g mole. These values will be used as appropriate for the temperature range of interest. Any variation of these parameters with temperature may be neglected. 

Figure 9. Kinetic energy release distributions for several dehydrogenation reactions. Data from reference 38.

As this work progressed, it became convenient for comparative purposes to express the pyrolysis results for a specific pyrolysis experiment in terms of the extent of the observed reaction of the initial organohalogen component content recovered chromatographically. The extent of reaction data as determined by the CGC analysis of the volatile reaction products for the pyrolysis of some representative simple mixtures of DBDPO are summarized in Table II. As illustrated by these data, the results obtained for the DBDPO/Sb203 mixture suggest that, in the absence of a polymer substrate, Sb203 exhibits the same extent of reaction as observed for other inert fillers such as glass beads or alumina. 

From the single component, simple mixture and ternary mixture extent of reaction data presented, it was concluded that the extent of DBDPO reaction in the ternary mixtures studied, which was measured by CGC and CGC/MS analysis, was greater than could be accounted for on the basis of the reactivity of the individual components initially present. Taken together these data suggest that a reaction intermediate or product was formed during the degradation of the ternary mixtures which was either (a) more reactive towards DBDPO itself or (b) a powerful catalyst for the subsequent dehalogenation of the DBDPO. 

Catalysis is demonstrated by the process that the radicals are generated by the oxidized form of the catalyst in the reaction with aldehyde, and the reduced form of the catalyst is rapidly oxidized by perbenzoic acid formed in the chain reaction. Data on the catalytic oxidation of aldehydes of different structures are found in Refs. [50,51]. 

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