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1.
Danov S. M. Kolesnikov V. A. Esipovich A. L. 《Russian Journal of Applied Chemistry》2010,83(1):168-170
The kinetics of benzene mononitration in excess of 45–70 wt % nitric acid in a homogeneous liquid phase was studied. The data
on the effects of temperature and nitric acid concentration on the reaction rate were obtained. 相似文献
2.
V. A. Rafeev Yu. I. Rubtsov T. V. Sorokina N. V. Chukanov 《Russian Chemical Bulletin》1999,48(1):66-70
The equilibrium of nitration of cellulose was studied at 13.1 and 20 °C in aqueous solutions of HNO3 (77.3–80.5 wt.%) forming quasi-homogeneous solutions with cellulose. At 20 °C under quasi-homogeneous conditions, the rates
of cellulose nitration are comparable to those of homogeneous nitration of alcohols. The effective nitration constants differ
substantially for heterogeneous and homogeneous reactions. Using IR spectra, the partial conversions in the nitration to the
2, 3 and 6 positions of the glucopyranose cycle and the effective equilibrium constants of formation of different isomeric
nitrates were estimated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 66–70, January, 1999. 相似文献
3.
Kinetics and mechanism of nitration of aromatic compounds using trichloroisocyanuric acid (TCCA)/NaNO2, TCCA-N,N-dimethyl formamide (TCCA-DMF)/NaNO2, and TCCA-N,N-dimethyl acetamide (TCCA-DMA)/NaNO2 under acid-free and Vilsmeier-Haack conditions. Reactions followed second-order kinetics with a first-order dependence on [Phenol] and [Nitrating agent] ([TCCA], [(TCCA-DMF)], or [(TCCA-DMA)] >> [NaNO2]). Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but did not fit well into the Hammett's theory of linear free energy relationship or its modified forms like Brown-Okamoto or Yukawa-Tsuno equations. Rate data were analyzed by Charton's multiple linear regression analysis. Isokinetic temperature (β) values, obtained from Exner's theory for different protocols, are 403.7 K (TCCA-NaNO2), 365.8 K (TCCA-DMF)/NaNO2, and 358 K (TCCA-DMA)/NaNO2. These values are far above the experimental temperature range (303-323 K), indicating that the enthalpy factors are probably more important in controlling the reaction. 相似文献
4.
The regularities of vapor-phase nitration of cellulose with HNO3 under conditions of natural convection and hindered heat removal in the absence of air were studied using the nonisothermal kinetic method. It was established that the nitration rate at the depth of conversion of 0.08 to 0.7 is described by the kinetic law d/dt =k
1
p/(1+), wherek
1 = 104.49±0.6 exp(–A/RT) s–1 atm–1, = 10–35.5±15.7exp(B/RT),A = 36.6±3.8 kl mol–1, andB = 203±88 kJ mol–1. The diffusion mechanism of vapor-phase nitration of cellulose, which explains the high value of activation energies, is discussed. The effective diffusion coefficient of HNO3 in cellulose at 25 °3.7 · 10–7 cm2 s–1) and the activation energy of diffusion (38.3±4.2 kJ mol–1) were estimated.For Part 1, see Ref. l.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1981–1985, August, 1996. 相似文献
5.
The esterification reaction of n-butanol and acetic acid has been performed in batch reactor in the presence of different homogeneous acid catalyst, namely sulfuric acid, nitric acid, and para toluene sulfonic acid (p-TSA). The objective of present research work is to investigate kinetic behavior of esterification reaction over the temperature range of 60°C–80°C. The effect of reaction parameter such as catalyst loading varied from 1% to 5% v/v and acid to alcohol molar ratio of 1:1, 1:3, and 1:5 has been observed. A pseudo homogeneous kinetic model has been applied. Kinetic parameters such as equilibrium constant, reaction rate constant, enthalpy, activation energy, and entropy were calculated by the experimental data for different acid catalyst system. It was observed that sulfuric acid gives higher conversion 73% than p-TSA 68.5% and nitric acid 66.25% at temperature of 80°C, 1:1 molar ratio and 3% catalyst concentration. The activation energy was estimated 36448.49, 23324.31 and 19060.156 J/mol K for three different catalyst sulfuric acid, nitric acid and p-TSA respectively. The enthalpy and entropy of the esterification reaction of acetic acid with n-butanol over three different catalysts has been calculated (Enthalpy: 25.788 KJ/mol, 12.256 KJ/mol, 28.320 KJ/mol, Entropy: 88.1 J/mol K, 45.298 J/mol K, 91.44 J/mol K) and found enthalpy is having positive value that shows reaction is endothermic. 相似文献
6.
The kinetics and mechanism of 2,4-dihydro-1,2,4-triazol-3-one nitration in nitric acid have been studied. The role of 2-nitro-2,4-dihydro-1,2,4-triazol-3-one as an intermediate has been determined. 相似文献
7.
The kinetics of vapor nitration of cellulose with nitric anhydride at various pressures was studied under conditions of natural convection in the absence of air, using the nonisothermal kinetic method. The process rate was found to be proportional to the N2O5 pressure. The nitration is described by a law of the dη/dt =k 1/(1+βν) type, wherek 1 = 103.82±0.5 exp[-(36000±(RT)]p N 2O5 s?1. β = 10?7.33±1.4exp[(41300±8000)/(RT)] s?1, s?1, within the extents of conversion from 0.04 to 0.4. At high levels of conversion, the nitration occurs with autoacceleration caused by the accumulation of the HNO3 formed. The diffusion mechanism of vapor nitration of cellulose was suggested and discussed. The values of the effective diffusion constant for N2O5 in cellulose and the corresponding activation energy (38.4±2.8 kJ mol?1) have been estimated. 相似文献
8.
<正>A mild,efficient and regioselective method for the mononitration of phenolic compounds is described using bismuth subnitrate/ charcoal in the presence of trichloroisocyanuric acid in CH_2Cl_2 at room temperature. 相似文献
9.
10.
M. Satish Kumar Y. Hemanth Sriram M. Venkateswarlu M. Sai Sudhakar Purugula Venkanna 《合成通讯》2018,48(1):59-67
Silica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions. 相似文献
11.
K. Kh. Dzumakaev A. D. Kagarlitskii G. T. Fedolyak 《Reaction Kinetics and Catalysis Letters》1986,30(2):289-295
The dependence of the rate constant on the temperature, nitrile concentration and amount of catalyst in benzonitrile hydration on a skeletal copper catalyst has been established. Activation energies have been determined. A reaction mechanism is suggested.
, . . .相似文献
12.
The rates of the formation of benzoguanamine from dicyandiamide and benzonitrile in the presence of a basic catalyst, have been measured by means of UV spectrophotometry. The rate is expressed as ν = k × [dicyandiamide]·[benzonitrile]·[KOH]. Since the addition of a small amount of cyanamide retards the rate, cyanamide cannot be an intermediate. Application of the rate data observed with p-methyl-, methoxy-, and chlorobenzonitriles to the Hammett's equation gives a positive value of +1·82. A probable mechanism involving a rate-determining attack of the conjugate base of dicyandiamide on benzonitrile is suggested and discussed. 相似文献
13.
Anelise M. Regiani Elisabete Frollini Guilherme A. Marson Guilherme M. Arantes Omar A. El Seoud 《Journal of polymer science. Part A, Polymer chemistry》1999,37(9):1357-1363
Commercially available cellulose (Avicell PH101) was successfully acylated under homogeneous solution conditions by the following procedure: 2.0 g of cellulose were stirred with 75 mL of N,N‐dimethylacetamide for 1 h at 150°C, 3.5 g of LiCl were added, the temperature was raised to 170°C, ca. 18.5 mL of the solvent were distilled and the suspension was cooled to room temperature and stirred overnight. The temperature of the clear cellulose solution was raised to 110°C, kept at that temperature for 1 h, an acid anhydride was added and the solution stirred at 110°C for additional 4 h. Acetates, propionates, butyrates, and acetate/propionate mixed ester were prepared with excellent control of the degree of substitution, DS, 1 to 3 for acetates, 2 and 3 for propionates and butyrates, and 3 for acetate/propionate. The degree of polymerization of cellulose is negligibly affected under these reaction conditions. The distribution of the acetyl moiety among the three OH groups of the anhydroglucose unit shows a preference for the C6 position. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1357–1363, 1999 相似文献
14.
Stoyko Gyurov Diana Rabadjieva Daniela Kovacheva Yoanna Kostova 《Journal of Thermal Analysis and Calorimetry》2014,116(2):945-953
The kinetics of air copper slag oxidation under nonisothermal conditions is studied using simultaneous TG–DTA at a varying heating rate of slag and flow rate of the oxidizing gas flux. The values of the kinetic parameters, activation energy and pre-exponential factor, have been determined based on: data from DTA by the methods of Kissinger and Ozawa; data from TG using an isoconversion method and the computation procedures of Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose. No relationship between the kinetic parameters and the oxidation gas flow rate has been established. The changes of the phase composition with temperature are investigated by X-ray powder diffraction analysis on the basis of data obtained for the products formed at the different stages of the oxidation process. The morphology of the oxidized slag as well as the elements distribution is studied by electron microscopy and EDS analysis. 相似文献
15.
An efficient and facile process has been developed for the regioselective C5 nitration of the N-protected indolines using ferric nitrate as the nitrating reagents. The reaction proceeded smoothly in moderate to excellent yields with high efficiency and broad substrate scope under mild conditions. In addition, the synthesized nitration products can be further transformed to 5-nitroindolines and C5-nitroindole derivatives. The method is operationally simple, efficient, and might have potential application in industry production. 相似文献
16.
Najmeh Nowrouzi Abdol Mohammad MehranpourElham Bashiri Zohre Shayan 《Tetrahedron letters》2012,53(36):4841-4842
The use of N-bromosuccinimide and silver nitrate as a convenient reagent system for the nitration of aromatic compounds under neutral and environmentally safer reaction conditions is described. 相似文献
17.
Ghigo G Causà M Maranzana A Tonachini G 《The journal of physical chemistry. A》2006,110(49):13270-13282
The viability of some nitration pathways is explored for benzene (B), naphthalene (N), and in part pyrene (P). In principle, functionalization can either take place by direct nitration (NO2 or N2O5 attack) or be initiated by more reactive species, as the nitrate and hydroxyl radicals. The direct attack of the NO2 radical on B and N, followed by abstraction of the H geminal to the nitro group (most likely accomplished by 3O2) could yield the final nitro-derivatives. Nevertheless, the initial step (NO2 attack) involves significant free energy barriers. N2O5 proves to be an even worst nitrating agent. These results rule out direct nitration at room temperature. Instead, NO3 and, even more easily, HO can form pi-delocalized nitroxy- or hydroxycyclohexadienyl radicals. A subsequent NO2 attack can produce several regio- and diastereoisomers of nitroxy-nitro or hydroxy-nitro cyclohexadienes. In this respect, the competition between NO2 and O2 is considered: the rate ratios are such to indicate that the NO3 and HO initiated pathways are the major source of nitroarenes. Finally, if the two substituents are 1,2-trans, either a HNO3 or a H2O concerted elimination can give the nitro-derivatives. Whereas HNO3 elimination is feasible, H2O elimination presents, by contrast, a high barrier. Under combustion conditions the NO2 direct nitration pathway is more feasible, but remains a minor channel. 相似文献
18.
The reaction of myristic acid (MA) and isopropyl alcohol (IPA) was carried out by using both homogeneous and heterogeneous catalysts. For a homogeneously catalyzed system, the experimental data have been interpreted with a second order, using the power‐law kinetic model, and a good agreement between the experimental data and the model has been obtained. In this approach, it was assumed that a protonated carboxylic acid is a possible reaction intermediate. After a mathematical model was proposed, reaction rate constants were computed by the Polymath* program. For a heterogeneously catalyzed system, interestingly, no pore diffusion limitation was detected. The influences of initial molar ratios, catalyst loading and type, temperature, and water amount in the feed have been examined, as well as the effects of catalyst size for heterogeneous catalyst systems. Among used catalysts, p‐toluene sulfonic acid (p‐TSA) gave highest reaction rates. Kinetic parameters such as activation energy and frequency factor were determined from model fitting. Experimental K values were found to be 0.54 and 1.49 at 60°C and 80°C, respectively. Furthermore, activation energy and frequency factor at forward were calculated as 54.2 kJ mol?1 and 1828 L mol?1 s?1, respectively. © 2008 Wiley Periodicals, Inc. 40: 136–144, 2008 相似文献
19.
20.
Khabarov Yu. G. Kuzyakov N. Yu. Veshnyakov V. A. Komarova G. V. Garkotin A. Yu. 《Russian Chemical Bulletin》2016,65(12):2925-2931
Russian Chemical Bulletin - The nitration of sulfate lignin by nitric acid in an aqueous-dioxane medium under homogeneous conditions was studied. The method proposed makes it possible to synthesize... 相似文献