Bronsted equation, for

Low Energy Activation in Each Step. In certain cases, the rule is, the better the thermodynamic of the step, the lower the energy activation (Polanyi-Semenov, Bronsted equations, for example). 

Calculate the identity rate constant, for the reaction of 4-nitrophenolate ion with 4-nitrophenyl acetate given that the Bronsted equation for the attack of substituted phenolate ions on the ester is ... 

The Bronsted equation for the correlation for the mutarotation of glucose catalysed by general bases (B) is... 

The reactivities of ammonium ion-catalysed reactions are several orders of magnitude larger than those predicted from the Bronsted Equation for the general acid-catalysed process. This result indicates a different mechanism and the favoured one involves the formation of an iminium ion (Scheme 28) intermediate which is present in substantial proportions at neutral pH. 

The following data give the dissociation constants for several acids that catalyze hydration of acetaldehyde. Also given are the rate constants for the hydration reaction catalyzed by each acid. Treat the data according to the Bronsted equation, and comment on the mechanistic significance of the result. 

Write the balanced chemical equation for (a) the thermal decomposition of potassium chlorate without a catalyst (b) the reaction of bromine with water (c) the reaction between sodium chloride and concentrated sulfuric acid, (d) Identify each reaction as a Bronsted acid—base, Lewis acid—base, or redox reaction. 

The (La3+( OCH3))2 and 9 Zn2+( OCH3) promoted methanolyses of the phos-phonates (22)17e and phosphonothioates (23)17g generally follow the same sort of trends as the phosphates and phosphorothioates discussed above so they need not be discussed in great detail here. Analysis of the linear Bronsted plots for the phospho-nates 22 gives the relationships shown in Equations (27)-(29) which shows the common trend that the j8lg observed for the metal-catalyzed reactions are greater than that of the methoxide reactions. Since the Leffler parameter, a, for the La3+-catalyzed... 

The hexadecyltrimethylammonium cation causes a modest increase in rate constant for the anion-anion reaction [Fe(CN)5(4-CNpy)]3-+CN-. This can equally well be interpreted according to the pseudophase model developed from the Olson-Simonson treatment of kinetics in micellar systems or by the classical Bronsted equation (135). 

As our basis we chose the Bronsted-Guggenheim (6) equation for the mean activity coefficient YR x t ie electrolyte in a solution of several electrolytes having cation R and anion X. The mean activity coefficient Y R>x is given by... 

Equation 1 is differentiated to calculate the ionic activity coefficients using the same technique as for non-electrolytes. Combining these ionic activity coefficients to form the mean ionic activity coefficients, y., we obtain the Bronsted-Guggenheim equations for two 1-1 electrolytes with a common ion ... 

Estimated pKa Values Based on Rate Constants for N-Methylation and Bronsted Equation [Eq. (15)1°... 

With the aid of the Bronsted equation [Eq. (15)] the reactivities of simple azoles or benzazoles may be predicted from a knowledge of their pKa values. While this equation was derived for N-methylation reactions using solvents such as DMSO and dimethyl sulfate, it can be applied to estimate nucleophilicity toward other alkylating agents in various solvents provided that (a) the Bronsted / values for the new systems are similar to the old one, and (b) that steric factors are unimportant. The foregoing discussion serves as a guide to indicate when such limitations apply. 

SAMPLE SOLUTION (a) Always start with an equation for an acid-base reaction. Ammonia is a Bronsted base and accepts a proton from the —OH group of acetic acid. Ammonia is converted to its conjugate acid, and acetic acid to its conjugate base. 

PROBLEM 15.1 Write a balanced equation for the dissociation of each of the following Bronsted-Lowry acids in water ... 

Second-order rate constants for the reactions of phenacyl bromide with a number of anionic or neutral nucleophiles in 3 2 (v/v) acetone-water have been measured at several temperatures.141 Correlation analysis with the Bronsted equation or Swain-Scott equation is not satisfactory. Better results were obtained with the two-parameter Edwards equation. 

Solvolysis of the R,R and R,S isomers of 2-bromo-9-(l-X-ethyl)fluorenes, X = Cl, Br, I, or OBs, in 25% (v/v) acetonitrile in water has been studied with respect to rates of formation of elimination products and of substitution products (X = OH or NHCOMe).142 The parent 9-(l-X-ethyl)fluorenes and the 2,2/-dibromo-9-(l-X-ethyl)-fluorenes were also studied. Various effects of leaving group and of the presence of nucleophiles on the competition between the reactions were observed and the Bronsted equation was applied to the results for the elimination reactions. A related study of solvolysis of 9-(X-methyl)fluorenes, X = I, Br, or Bs, was also carried out, in which the Swain-Scott equation was applied to nucleophilic selectivities in the S 2 reactions.143... 

Rate constants of ketonization of acetophenone enol along paths (a) and (b) have been be estimated using the Bronsted Equation (16).20 Those predicted for path (a) are orders of magnitude below the observed rate constant k c = 0.18 s 1, while those for path (b) were found to be in reasonable agreement with experiment. The concerted mechanism (c) does not satisfactorily account for structure-reactivity relationships observed in aqueous solution. It may, however, well be the dominant mechanism in aprotic solvents containing small amounts of water. 

The individual steps in Scheme 11.15 should have linear Bronsted dependences where and C are the general parameters corresponding to the equation for kn. The overall... 

It is possible that this relationship between the thermal effect of the complex reaction and its observed activation energy is responsible for the fact that the Bronsted equation (or its analogs) appear to be valid for some elementary reactions as well. A question arises whether the observed activation energy can be higher than the activation energy of elementary steps. 

Figure 1.14 a Equation for the cyclization of geraniol, and b possible mechanism in the presence of zeolite Y, a solid acid catalyst that has both Bronsted and Lewis acid sites. 

One of the most useful features of the Bronsted system is that is takes into account what happens after an acid-base reaction occurs. You all know HC1 is an acid, so let s write an equation for it behaving as an acid. That is, let s allow HC1 to give away its hydrogen ion. 

---