Acetic acid rate constant

Solvolysis of rra -[Co(en)2L2]+, where L = 2-, 3-, or 4-methyl benzoate or 2,3-, 2,4-, 3,4-, or 3,5-dimethyl benzoate, has been studied in acetic acid. Rate constants do not correlate with electronic properties of the ligands, but there is a rough trend with steric factors, particularly in that compounds containing an o-methyl substituent in the benzoate ligands react relatively rapidly. ... 

The process of acid dissociation can be thought of as comprising two steps, namely ionisation and dissociation of the ion-pair into separate products. The first step may be studied in isolation if a solvent of low dielectric constant is employed, as the second process then occurs to a negligible extent. For example, the rates of proton exchange in acetic acid (dielectric constant, 6.27) are given [73] in Table 15. The measured rate,... 

The equilibrium constant K, the rate constants and and the dependences of all these quantities on temperature were determined. In the absence of added acetic acid, the conversion of nitric acid into acetyl nitrate is almost quantitative. Therefore, to obtain at equilibrium a concentration of free nitric acid sufficiently high for accurate analysis, media were studied which contained appreciable concentrations (c. 4 mol 1 ) of acetic acid. 

The dependence of the zeroth-order rate constants on the concentration of acetyl nitrate is shown in fig. 5.1 in the absence of added acetic acid the rate increases according to the third power of the concentration of acetyl nitrate, but when acetic acid is added the dependence becomes... 

The kinetics of the nitration of benzene, toluene and mesitylene in mixtures prepared from nitric acid and acetic anhydride have been studied by Hartshorn and Thompson. Under zeroth order conditions, the dependence of the rate of nitration of mesitylene on the stoichiometric concentrations of nitric acid, acetic acid and lithium nitrate were found to be as described in section 5.3.5. When the conditions were such that the rate depended upon the first power of the concentration of the aromatic substrate, the first order rate constant was found to vary with the stoichiometric concentration of nitric acid as shown on the graph below. An approximately third order dependence on this quantity was found with mesitylene and toluene, but with benzene, increasing the stoichiometric concentration of nitric acid caused a change to an approximately second order dependence. Relative reactivities, however, were found to be insensitive... 

Ratio of first order rate constant for solvolysis in indicated solvent to that for solvolysis in acetic acid at 25 C... 

One of the most sensitive tests of the dependence of chemical reactivity on the size of the reacting molecules is the comparison of the rates of reaction for compounds which are members of a homologous series with different chain lengths. Studies by Flory and others on the rates of esterification and saponification of esters were the first investigations conducted to clarify the dependence of reactivity on molecular size. The rate constants for these reactions are observed to converge quite rapidly to a constant value which is independent of molecular size, after an initial dependence on molecular size for small molecules. The effect is reminiscent of the discussion on the uniqueness of end groups in connection with Example 1.1. In the esterification of carboxylic acids, for example, the rate constants are different for acetic, propionic, and butyric acids, but constant for carboxyUc acids with 4-18 carbon atoms. This observation on nonpolymeric compounds has been generalized to apply to polymerization reactions as well. The latter are subject to several complications which are not involved in the study of simple model compounds, but when these complications are properly considered, the independence of reactivity on molecular size has been repeatedly verified. 

Hydrolysis of TEOS in various solvents is such that for a particular system increases directiy with the concentration of H" or H O" in acidic media and with the concentration of OH in basic media. The dominant factor in controlling the hydrolysis rate is pH (21). However, the nature of the acid plays an important role, so that a small addition of HCl induces a 1500-fold increase in whereas acetic acid has Httie effect. Hydrolysis is also temperature-dependent. The reaction rate increases 10-fold when the temperature is varied from 20 to 45°C. Nmr experiments show that varies in different solvents as foUows acetonitrile > methanol > dimethylformamide > dioxane > formamide, where the k in acetonitrile is about 20 times larger than the k in formamide. The nature of the alkoxy groups on the siHcon atom also influences the rate constant. The longer and the bulkier the alkoxide group, the lower the (3). 

In a study of the kinetics of the reaction of 1-butanol with acetic acid at 0—120°C, an empirical equation was developed that permits estimation of the value of the rate constant with a deviation of 15.3% from the molar ratio of reactants, catalyst concentration, and temperature (30). This study was conducted usiag sulfuric acid as catalyst with a mole ratio of 1-butanol to acetic acid of 3 19.6, and a catalyst concentration of 0—0.14 wt %. 

Continuous esterification of acetic acid in an excess of -butyl alcohol with sulfuric acid catalyst using a four-plate single bubblecap column with reboiler has been studied (55). The rate constant and the theoretical extent of reaction were calculated for each plate, based on plate composition and on the total incoming material to the plate. Good agreement with the analytical data was obtained. 

The solvolysis of 2, 35-3-(4-methoxyphenyl)but-2-yl/>-toluensulfonate in acetic acid can be followed by several kinetic measurements (a) rate of decrease of observed rotation (k ) rate of release of the leaving group (k,) and, when 0-labeled sulfonate is used, the rate of equilibration of the sulfonate oxygens (k ). At 25°C, the rate constants are... 

The batch reactor initially contains 227 kg of acetyiated castor and die initial temperature is 613 K. Complete hydrolysis yields 0.156 kg acetic acid per kg of ester. Eor diis reaction, die specific reaction rate constant k is... 

The rate constant for the acid-catalyzed hydrolysis of ethyl acetate is... 

The most reliable method of preparing benzofuroxans is by decomposition of o-nitrophenyl azides. Decomposition can be achieved by irradiation, or more usually by pyrolysis temperatures between 100° and 1.50° are commonly used. Refluxing in glacial acetic acid is the recommended procedure for 4- or 5-sub-stituted 2-nitrophenyl azides, but with 3- or 6-substituted compounds higher boiling solvents are usually necessary. Quantitative studies on the reaction rate have been made, and a cyclic transition state invoked, an argument which has been used to account for the greater difficulty of decomposition of the 6-substituted 2-nitrophenyl azides. Substituent effects on the reaction rate have also been correlated with Hammett a constants, ... 

The above generalities apply particularly to palladium. Hydrogenation over platinum or rhodium are far less sensitive to the influence of steric crowding. Reduction of 1-t-butylnaphthalene over platinum, rhodium, and palladium resulted in values of /ci//c2 of 0.42, 0.71, and 0.024, respectively. Also, unlike mononuclear aromatics, palladium reduces substituted naphthalenes at substantially higher rates than does either platinum or rhodium. For example, the rate constants, k x 10 in mol sec" g catalyst", in acetic acid at 50 C and 1 atm, were (for 1,8-diisopropylnaphthalene) Pd (142), Pt(l8.4), and Rh(7.1)(25). 

The positive bromination of aromatics ethers was first studied by Bradfield et al.193 and by Branch and Jones194. The reaction of hypobromous acid in 75 % aqueous acetic acid with benzyl 4-nitrophenyl ether and 4-nitrophenetole at 20 °C was very rapid and approximately second-order193. The value of k2/[H+] remained constant in the [H+] range 0.005-0.090 M for the effect of added mineral acids on the bromination of 4-nitroanisole and 4-nitrophenetole (at 19.8 °C)194. The variation in reaction rate with the percentage of acetic acid in the medium was also studied and showed a large increase in the 0-10 % range with a levelling off at approximately 25 % acetic acid (Table 52) this was attributed... 

Berliner et a/.284-8 have examined kinetics of bromination in aqueous acetic acid in an attempt to find the acid concentration at which the change in kinetic order principally occurs, though it follows from the earlier work that this will depend upon the aromatic reactivity. In 50 % acid the bromination of naphthalene was second-order overall284, and at constant ionic strength the rate coefficient showed a dependence on [Br-] according to equation (140)... 

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). 

Unionized mercuric acetate is also a mercurating species, for the second-order rate coefficient for mercuration of benzene by mercuric acetate in acetic acid at 25 °C is 0.41 x 10"7. If mercuration took place via ionized acetate ion pairs HgOAc+OAc" for which AT, the equilibrium constant can be estimated at 2 x 10"8, then since the rate of mercuration by this ion pair will be approximately the same as by the acetoxymercury perchlorate ion pair for which k2 the second-order rate coefficient has been determined (above) as 0.37x10"3 at 25 °C, the observed second-order rate should be 2 x 10"8 x0.37 x 10"3 = 0.74xl0-11. This is so different from the rate actually observed that mercuration by the ion pair can be eliminated which leaves ionized mercurcy acetate as the only possible mercurating species439. 

Shatenshtein et al.5ia also found a similar dependence of rate coefficient upon the concentrations of stannic chloride and acetic acid in the dedeuteration of [l,4-2H2]-durene in benzene. Rate coefficients increased linearly with increasing stannic chloride concentration and at a constant value of this the rate increased only slightly with increasing acetic acid concentration, except at high concentrations of the latter when the rate then decreased (Table 155). Cryoscopic mea-... 

The rate of the reaction in various buffer solutions, covering the pH range 4-8, was determined, and in hydrogen phosphate-dihydrogen phosphate buffers the rate at constant pH decreased as the concentration of dihydrogen phosphate increased. Similarly, with acetic acid-acetate and phosphoric acid-dihydrogen phosphate buffers the rate was inversely dependent upon the concentration of the molecular acid in addition, with the latter buffer, the kinetic plots showed an unexplained departure from linearity after 50 % reaction. 

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