Nitration temperature coefficient

Because of these difficulties, special mechanisms were proposed for the 4-nitrations of 2,6-lutidine i-oxide and quinoline i-oxide, and for the nitration of the weakly basic anilines.However, recent remeasurements of the temperature coefficient of Hq, and use of the new values in the above calculations reconciles experimental and calculated activation parameters and so removes difficulties in the way of accepting the mechanisms of nitration as involving the very small equilibrium concentrations of the free bases. Despite this resolution of the difficulty some problems about these reactions do remain, especially when the very short life times of the molecules of unprotonated amines in nitration solutions are considered... 

Manganous sulphate5 and ferric salts in general accelerate the decomposition of hydrogen peroxide.6 The sulphate is less active than the chloride or nitrate. With dilute solutions of the salts the effect is proportional to the concentration of the peroxide and that of the iron ions, whilst in the presence of acids it is inversely proportional to the hydrogen-ion concentration. The temperature coefficient of the reaction is 3 25 for ten degrees. ... 

On plotting these values, the curve shown in Fig. 71 is obtained. The curve shows distinct breaks at 32° (transition point for and a-rhombic) and at 125° (transition point for rhombohedral and regular or cubic). No detectible break, however, was observed at 84° (transition point for a-rhombic and rhombohedral), showing that the temperature coefficients of solubility of a-rhombic and rhombohedral ammonium nitrate are practically the same. 

The nitration coefficient is usually in the range of 3-6 and the nitration temperature is 5-25 °C. 100 kg diethylene glycol can produce 168.7 kg of nitrate ester with a theoretical yield of 91.3 %. 

Pentaerythritol trinitrate is prepared by a condensation reaction between formaldehyde and propionic aldehyde to pentaerythritol, which is farther nitrated by a mixed acid of nitric acid and sulfuric acid. The preparation condition is nitration coefficient of 5-6, nitration temperature of 20-25 °C, and nitration time of 25-30 min. The nitration yield at 10 °C with a mixed acid of 45 % nitric acid and 55 % sulfuric acid is 197-198 %, about 93 % of the theoretical yield. If 20 % fuming sulfuric acid is used, the yield can be increased to 97-98 % of the theoretical yield. The parameters of stability treatment with water-washing coefficient of 5 are listed in Table 5.56. 

For three actinide ions, viz. Th, U, and UOl", the enthalpy changes AH° accompanying the hydrolytic reactions have also been determined. In two of these investigations, pertaining to Th [259] and UO [66], the values of A// have been measured calorimetrically. In all other cases [32,40,55,67] the values have been calculated from the temperature coefficient of the equilibrium constant, a method that is generally less accurate. Perchlorate media have been used, except for one study of Th " [259] and one of [55] which refer to chloride and nitrate media, respectively. 

Among the properties sought in the solvent are low cost, avadabihty, stabiUty, low volatiUty at ambient temperature, limited miscibility in aqueous systems present in the process, no solvent capacity for the salts, good solvent capacity for the acids, and sufficient difference in distribution coefficient of the two acids to permit their separation in the solvent-extraction operation. Practical solvents are C, C, and alcohols. For industrial process, alcohols are the best choice (see Amyl alcohols). Small quantities of potassium nitrate continue to be produced from natural sources, eg, the caUche deposits in Chile. 

The conclusion that the nitration of quinoline in sulphuric acid takes place via the conjugate acid has been confirmed by Moodie et al.50, who measured the rates of nitration of a wide range of heterocyclic compounds in nitric acid-sulphuric acid mixtures at a range of temperatures. A summary of the second-order rate coefficients and Arrhenius parameters is given in Table 4. From an analysis of the shapes of the plots of log k2 versus sulphuric acid acidity (or some function of this), it was concluded that all of the compounds starred in Table 4... 

Toluene is continuously nitrated to mononitrotoluene in a cast-iron vessel, 1 m diameter, fitted with a propeller agitator 0.3 m diameter rotating at 2.5 Hz. The temperature is maintained at 310 K by circulating 0.5 kg/s cooling water through a stainless steel coil 25 mm o.d. and 22 mm i.d. wound in the form of a helix, 0.80 m in diameter. The conditions are such that the reacting material may be considered to have the same physical properties as 75 per cent sulphuric acid. If the mean water temperatute is 290 K, what is the overall coefficient of heat transfer ... 

The rate coefficient (k2 enc) for the collision of two species is given by 8RT/3Z (where Z is the viscosity of the medium at the reaction temperature), the Smoluchowski equation. This is the maximum possible rate of reaction, which is controlled by the rate at which the two reacting species diffuse together. For nitration in >90% H2S04, where nitric acid is completely ionized, if exclusively the free base nitrates the rate coefficient (k2 fb) would equal k2 obs KJhx (where Ka is the ionization constant of the base, and hx the acidity function that it follows). Thus, if k2 fb> k2 enc free base nitration is precluded, but if... 

The above procedure is now applied to two ethanol-water (8, 9) and five 1-propanol-water systems (9) which have been saturated with an inorganic salt and which show partial miscibility. The vapor pressures and molar volumes (10), and second virial coefficients of water (11), ethanol (12), and 1-propanol (IS) were obtained by interpolation of literature data. The vapor pressures of water saturated with salts over a temperature range are available for all salts (14) except lead nitrate. Such data are unavailable for both alcohols saturated with salt. Hence a correction to the saturation vapor pressure is made by multiplying by the ratio of the vapor pressure of alcohol saturated with salts to the vapor pressure... 

Estimation of the diffusion coefficient from the data on the electrical conductivity of nitrate glasses has shown that, in the KN03 + Ca(N03)2 matrix, the diffusional decay of N03 radicals at T < 297 K and t < 102s is negligible. A rise of temperature in the low-temperature region results in a small increase in the slope of kinetic curves. Thus, just as in the case of the decay of N03 in the water-alkaline matrix, the decay of N03 radicals in the KN03 + Ca(N03)2 matrix at low temperatures is an activated electron tunneling process. 

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