Second order reaction rate coefficients for diisocyanates and alcohols at 115°C X 10 (1 mole" sec" ) [Pg.549]

TABLE 2. Second-order reaction rate coefficients, a> at 15, 25 and 40 °C, and activation parameters for the reactions 10-4 M of l-chloro-2,4-dinitrobenzene with piperidine in hydroxylic solvents4813 [Pg.1222]

Yamase and Goto406 determined first- and second-order rate coefficients for the aluminium chloride-catalysed reaction of halide derivatives of benzoic acid (lO5 = F, 1.73 Cl, 4.49 Br, 4.35 I, 0.81) and phenylacetic acid (105fc2 = F, 12 Cl, 21 Br, 9 I, 6) with benzene. The maxima in the rates for the acid chloride are best accommodated by the assumption that a highly (but not completely) polarised complex takes part in the transition state. Polarisation of such a complex would be aided by electron supply, and consistently, the acetyl halides are about a hundred times as reactive as the benzoyl compounds (see p. 180, also Tables 105 and 108). [Pg.173]

The observed second-order rate coefficients can, in all cases, be treated empirically as consisting of the sum of a second-order rate coefficient (for the uncatalyzed reaction) and the product of a third-order rate coefficient and the catalyst concentration (for the catalyzed reaction), as indicated by eqn. (4). If the catalyst is a base this constitutes base catalysis in a formal sense, at least. Nevertheless, [Pg.421]

Base catalysis was shown not to be significant on two grounds. Firstly, the second-order rate coefficients for the two sets of acetate buffer data are the same within experimental error, and secondly, the addition of base of concentrations 0.05 and 0.2 M to the reaction with water caused a negligible change in the rate coefficient. [Pg.210]

Streitweiser et al.591 have measured rates of base-catalysed dedeuteration and detritiation and have attempted to discover details of the reaction mechanism. Second-order rate coefficients for the reaction of some polycyclics with lithium cyclohexylamide in cyclohexylamine are given in Table 179, and it can be seen [Pg.272]

What is the significance of the parameter P = (HiCbiPa) At in the choice and the mechanism of operation of a reactor for carrying out a second-order reaction, rate constant ki, between a gas A and a second reactant B of concentration Cgt in a liquid In the above expression Da is the diffusivity of A in the liquid and ki is the liquid-film mass transfer coefficient. What is the reaction factor and how is it related to pi [Pg.741]

The effect of metal-ion catalysis (especially that of cadmium ion) in the above reaction has been studied628, and in Table 201 are listed the first-order rate coefficients for protodeboronation of 2,6-dimethoxybenzeneboronic acid in malonic acid-sodium malonate buffer or perchloric acid, observed in the absence ( ) or presence ( ) of cadmium ion, together with the second-order rate coefficients (k2) obtained by dividing the difference of these values by the cadmium ion concentration. The data of the first ten rows of Table 201 are plotted in Fig. 4 and the [Pg.298]

Area-based physical mass transfer coefficient, m/s Area-based chemical mass transfer coefficient, m/s Volumetric physical mass transfer coefficient, 1/s Volumetric chemical mass transfer coefficient, 1/s Second order reaction rate constant, 1/s Generalized variable for a second-order reaction, [Pg.408]

The phenomenon was established firmly by determining the rates of reaction in 68-3 % sulphuric acid and 61-05 % perchloric acid of a series of compounds which, from their behaviour in other reactions, and from predictions made using the additivity principle ( 9.2), might be expected to be very reactive in nitration. The second-order rate coefficients for nitration of these compounds, their rates relative to that of benzene and, where possible, an estimate of their expected relative rates are listed in table 2.6. [Pg.27]

Bimolecular reactions have been described in Chaps. 1 and 3 of this book. The efficiency of these processes can depend on the temperature of the gas. All production and destruction terms (in units of cm s ) in equation (4.1) can be written as kijUiUj for bimolecular (second-order) reactions and kiUi for first-order reactions, with kij the rate coefficient of the reaction between species i and j and n the density of the reactant(s). More details on these expressions can be found in Wakelam et al. [22]. [Pg.123]

In 75 % aqueous acetic acid, the bromination of fluorene at 25 °C obeys second-order kinetics in the presence of bromide ion and higher orders in its absence287, with Ea (17.85-44.85 °C) = 17.4, log A = 10.5 and AS = —12.4 however, these values were not corrected for the bromine-tribromide ion equilibrium, the constant for which is not known in this medium, and so they are not directly comparable with the proceeding values. In the absence of bromide ion the order with respect to bromine was 2.7-2.0, being lowest when [Br2]initial was least. Second- and third-order rate coefficients were determined for reaction in 90 and 75 wt. % aqueous acetic acid as 0.0026 and 1.61 (k3/k2 = 619), 0.115 and 12.2 (k3/k2 = 106) respectively, confirming the earlier observation that the second-order reaction becomes more important as the water content is increased. A value of 7.25 x 106 was determined for f3 6 (i.e. the 2 position of fluorene). [Pg.119]

Notice that the molar density of key-limiting reactant A on the external surface of the catalytic pellet is always used as the characteristic quantity to make the molar density of component i dimensionless in all the component mass balances. This chapter focuses on explicit numerical calculations for the effective diffusion coefficient of species i within the internal pores of a catalytic pellet. This information is required before one can evaluate the intrapellet Damkohler number and calculate a numerical value for the effectiveness factor. Hence, 50, effective is called the effective intrapellet diffusion coefficient for species i. When 50, effective appears in the denominator of Ajj, the dimensionless scaling factor is called the intrapellet Damkohler number for species i in reaction j. When the reactor design focuses on the entire packed catalytic tubular reactor in Chapter 22, it will be necessary to calcnlate interpellet axial dispersion coefficients and interpellet Damkohler nnmbers. When there is only one chemical reaction that is characterized by nth-order irreversible kinetics and subscript j is not required, the rate constant in the nnmerator of equation (21-2) is written as instead of kj, which signifies that k has nnits of (volume/mole)"" per time for pseudo-volumetric kinetics. Recall from equation (19-6) on page 493 that second-order kinetic rate constants for a volnmetric rate law based on molar densities in the gas phase adjacent to the internal catalytic surface can be written as [Pg.540]

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