Kinetics and mechanism of the liquid-phase reaction of 2,4-dinitrotoluene with ozone in the presence of manganese(II) acetate

The kinetics and the mechanism of the liquid-phase oxidation of 2,4-dinitrotoluene with ozone in the presence of manganese(II) acetate have been investigated. The major products of 2,4-dinitrotoluene oxidation with ozone in acetic anhydride are 2,4-dinitrobenzyl acetate (65.8%) and 2,4-dinitrobenzylidene diacetate (18.8%). The effect of the manganese(II) acetate concentration on the selectivity of substrate oxidation at the methyl group is reported. A redox catalysis mechanism providing an explanation to experimental data is considered.     

THz spectroscopic investigation of 2,4-dinitrotoluene

We have investigated the terahertz (THz) spectrum of 2,4-DNT by using Fourier transform infrared spectroscopy in the 0.2–19.5 THz region. We also examined low-frequency intermolecular or phonon modes between 0.2 and 1.8 THz via THz time-domain spectroscopy. The extracted absorption coefficient and refractive index of an intermolecular band at 1.08 THz are 110 cm⁻¹ and 1.67, respectively. Density functional theory (DFT) was applied to obtain structure and vibrational frequencies of 2,4-DNT. The calculated results are in agreement with the experimental data. Observed vibrational frequencies have been interpreted using DFT. Two intermolecular or phonon modes were identified at 1.08 and 2.52 THz.     

Ozone reaction with 2,4-dinitrotoluene in acetic acid solution

2,4-Dinitrotoluene reacts with ozone along two concurrent pathways: at the aromatic ring yielding stable against ozonolysis hydroperoxide, and at the methyl group with retention of the aromatic structure. The relative amount of products undergoing oxidation at the aromatic ring and at the methyl group depends on the ozonation conditions, especially on the process temperature.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 11, 2004, pp. 1678–1680.Original Russian Text Copyright © 2004 by Andreev, G. Galstyan, A. Galstyan.     

Enhanced degradation of 2,4-dinitrotoluene by ozonation in the presence of manganese(II) and oxalic acid

Manganese catalytic ozonation of 2,4-dinitrotoluene (DNT) in the presence of oxalic acid was studied. The addition of manganese ion (Mn²⁺) or oxalic acid alone in ozonation process did not enhance DNT degradation, but the addition of Mn²⁺ coupled with oxalic acid accelerated degradation of DNT. The DNT degradation efficiency was influenced by carbonate in the catalytic ozonation process. Kinetics study showed that Mn²⁺ catalytic ozonation significantly promoted the decomposition of ozone. Experimental results of electron spin resonance (ESR) demonstrated that addition of Mn²⁺ and oxalic acid produced much hydroxyl radicals in catalytic ozonation system than that in single ozonation system. These results suggested that catalytic ozonation followed hydroxyl radical-type mechanism. Mn²⁺ promoted decomposition of ozone to produce hydroxyl radical and it was oxidized into manganese oxide. Manganese oxide was reduced into Mn²⁺ by oxalic acid, which is the key step of catalytic process. Based on above results, a cycle catalytic mechanism of Mn²⁺ was proposed. Intermediates were determined by HPLC and GC–MS, and they mainly included aromatic organics and aliphatic carboxylic acids.     

Thermochemistry of the binary system nitrocellulose+2,4-dinitrotoluene

Melting enthalpy and mixing enthalpy of binary system 2,4-dinitrotoluene and nitrocellulose were determined by DSC method. The maximum value of mixing enthalpy was H _max ^M=1.38 kJ mol⁻¹ for molar fraction x _w24DNT = 0.501. The Flory-Huggins parameter (c) was estimated. The solubility curves and glass transition temperatures were predicted and compared with the experimental results. The measurements were performed for the samples with different times of storage at room temperature. The analysis of melting peaks for the mixture leads to the conclusion that for the long periods of storage the melting of 2,4-dinitrotoluene takes place in the confined spaces (pores) and unconfined space (bulk). The crystallization and melting is observed during the short time of storage in mixtures with low nitrocellulose content and in the case of mixtures with a large amount of NC the glass transition is additionally observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Oxidation of fullerenes with ozone

Heterophase and liquid-phase oxidation reactions of fullerene with ozone and the data on chemiluminescence generated in these reactions were considered and classified for the first time.     

Enzymatic biosensor for the electrochemical detection of 2,4-dinitrotoluene biodegradation derivatives

In this work, we demonstrate for the first time that 4-methyl-5-nitrocatechol (4M5NC) and 2,4,5-trihydroxytoluene (2,4,5-THT), two compounds obtained from the 2,4-DNT biodegradation are recognized by polyphenol oxidase as substrates. An amperometric biosensor is described for detecting these compounds and for evaluating the efficiency of the 2,4-DNT conversion into 4M5NC in the presence of bacteria able to produce the 2,4-DNT-biotransformation. The biosensor format involves the immobilization of polyphenol oxidase into a composite matrix made of glassy carbon microspheres and mineral oil. The biosensor demonstrated to be highly sensitive for the quantification of 4M5NC and 2,4,5-THT. The analytical parameters for 4M5NC are the following: sensitivity of (7.5 ± 0.1) × 10⁵ nAM⁻¹, linear range between 1.0 × 10⁻⁵ and 8.4 × 10⁻⁵ M, and detection limit of 4.7 × 10⁻⁶ M. The sensitivity for the determination of 2,4,5-THT is (6.2 ± 0.6) × 10⁶ nAM⁻¹, with a linear range between 1.0 × 10⁻⁶ and 5.8 × 10⁻⁶ M, and a detection limit of 2.0 × 10⁻⁷. Under the experimental conditions, it was possible to selectively quantify 4M5NC even in the presence of a large excess of 2,4-DNT. The suitability of the biosensor for detecting the efficiency of 2,4-DNT biotransformation into 4M5NC is demonstrated and compared with HPLC-spectrophotometric detection, with very good correlation. This biosensor holds great promise for decentralized environmental testing of 2,4-DNT.     

Oxidation of 2-methylnaphthalene with ozone

In the oxidation of 2-methylnaphthalene with ozone in acetic acid, the oxidant reacts mainly at the double bonds of the substituted aromatic ring to give peroxy compounds. In the presence of cobalt diacetate and sodium bromide, oxidation of the 2-methyl group occurs with formation of 2-naphthoic acid. The major product in the oxidation of 2-methylnaphthalene with ozonated transition metal compounds is 2-methyl-1,4-naphthoquinone.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 12, 2004, pp. 1829–1830.Original Russian Text Copyright © 2004 by Mamchur, Galstyan.     

Catalytic wet air oxidation of 2-nitrotoluidine and 2,4-dinitrotoluene

The rates of wet air oxidation of 2-nitrotoluidine and 2,4-dinitrotoluene in the presence of excess oxygen and at different temperatures and oxygen pressures was investigated. Oxidation experiments were carried out at temperatures between 180 and 225^oC and oxygen partial pressures of 1,0-3,0 MPa, in a 280 mL glass vessel-inserted stainless steel reactor. Copper sulfate (CuSO₄ .5H₂O) was used as a catalyst, and the effect of catalyst loading was studied by varying the concentration: 0.75, 2.5 and 25 mg/L as Cu²⁺. Addition of Cu²⁺ ions in the reaction media accelerated 2-nitrotoluidine oxidation nearly ten times even if it exists in trace amount in the reaction medium (0.75 ppm Cu²⁺). Unfortunately copper did not show catalytic effect for the oxidation of 2,4-dinitrotoluene. This revised version was published online in August 2006 with corrections to the Cover Date.     

Oxidation of p-cresol with ozone in acetic anhydride

Preparation of aromatic alcohols and aldehydes by oxidation of p-cresol with ozone in acetic anhydride in the presence of sulfuric acid, manganese acetate, and potassium bromide was studied. The optimal oxidation conditions were determined.     

Oxidation of ferrocene with ozone and chemiluminescence

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2529–2530, December, 1995.     

Molecularly imprinted polymers labeled with amino-functionalized carbon dots for fluorescent determination of 2,4-dinitrotoluene

The authors have prepared amino-functionalized carbon dots (AC-dots) and applied them to fluorescently label a molecularly imprinted polymer (MIP) prepared by using 2,4-dinitrotoluene (DNT) as a template. Since DNT can retard vinyl polymerization, poly(methyl acrylate-co-acrylic acid) was used as a monomer. Non-imprinted polymers (NIPs) were also synthesized in order to compare data. As expected, MIPs exhibit higher adsorption than NIPs, with imprinting efficiencies ranging from 2 to 2.5. DNT is specifically captured by the cavities in the MIP and interact with AC-dots on the surface, resulting in quenching of the fluorescence of the AC-dots. Response to DNT reaches equilibrium within ~30 min. The method has a dynamic range that extends from 1 to 15 ppm, and allows for quantitation of DNT in aqueous solutions, with a detection limit of 0.28 ppm. Selectivity tests conducted in presence of DNT analogs demonstrated the selective recognition of DNT.

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Graphical Abstract Schematic of the preparation of molecularly imprinted polymers labeled with amino-functionalized carbon dots (AC-dots) for the quenchometric determination of 2,4-dinitrotoluene (DNT).

     

Oxidation of 2-acetoxytoluene with ozone in acetic anhydride

Kinetics and mechanism of the reaction of ozone with 2-acetoxytoluene in acetic anhydride in the presence of sulfuric acid were studied. It was shown that the prevailing reaction route under these conditions is ozonolysis (89%), and the selectivity of the oxidation of the substrate by the methyl group is no higher 9%. However, in the presence of manganese(II) sulfate as a catalyst, the selectivity increases to 76%. The major reaction products were 2-acetoxybenzyl acetate (59%) and 2-acetoxybenzylidene diacetate (17%). In the presence of a manganese bromide catalyst, the oxidation depth increases, and the major reaction product is already 2-acetoxybenzylidene (66%), while the yield of 2-acetoxybenzyl acetate is 15%. The mechanism of the redox catalysis is considered, that explains the experimental results.     

Diphenylamine as an n and π donor in the solid-state reaction of 2,4-dinitrotoluene with diphenylamine

The kinetics and mechanism of the reaction of 2,4-dinitrotoluene with diphenylamine were studied in the solid state. The reaction product is a charge transfer complex with a localized intermolecular interaction as shown by uv and ir spectroscopy. The solid-state studies were complemented by some NMR studies in CCl₄. A novel feature of the study reveals that diphenylamine in this case is a much more powerful n donor than a π donor.