Nitro compounds analysis

Analysis There are two general ones based on reduction of nitrile or nitro compound (a) nitrile route... 

Analysis The nitro compound looks like a Diels-Alder adduct, so we know where to put the double bond ... 

The nitro compound in Et2NH (70 mol equiv) was either heated under reflux with (EtO)2PMe (2- 5 mol equiv) under N2, or the mixture was heated in an autoclave at 57°C, until the reaction was complete as shown by GC analysis of the reaction mixture (4-7d). The excess Et2NH was removed under vacuum and the residue was chromatographed (alumina) to give the product which was further purified by distillation or crystallization. 

In summary, examples of the successful use of silica gel as a conventional stationary phase are in the analysis of mixtures containing polarizable and relatively low polarity solutes typified by mixtures of aromatic hydrocarbons, polynuclear aromatics, nitro compounds, carotenes and vitamin A formulas. 

See entry DIFFERENTIAL thermal analysis (reference 1) See other iv-NITRO COMPOUNDS... 

The increasing concerns of the public and the need for monitoring very low concentrations of toxic compounds means that detection at levels below ig kg-1 are required in many areas of analysis. Pesticides in the food chain, toxic materials in incineration and waste products and traces of nitro-compounds in finger washings of a person suspected of handling explosives, all involve analysis for low concentrations. 

From among the different classes of compounds considered in this work, most of the computational work was done on amines, while less examples are found for nitro compounds and very few for nitroso ones. The different studies may be classified into several major areas (1) conformational analysis and structural investigation (2) spectroscopic experiments and study of chemical effects (3) investigation of chemical reactions mechanism (4) heats of formation and density calculations, especially of high energetic materials. In the following sections we will concentrate on molecular mechanics based research studies, or on such where molecular mechanics calculations played a... 

The nitro group is of high importance in organic chemistry, in particular in aromatic compounds because of its strong electron acceptor capacity. In accordance with this property, the nitro group has low-lying occupied and unoccupied orbitals, and the characteristic IPs of nitro compounds are usually found higher than 10 eV, which may lead to problems in the analysis of PE spectra. 

Although likewise unequivocally dimeric as solids, 2,6-dimethyl- and 2,4,6-trimethylnitrosobenzene (41 and 42) allow for relatively unequivocal thermochemical analysis of both the monomeric and dimeric gases. The desired enthalpies of formation67 of monomeric 41 and 42 are 207.3 12.3 and 140.6 12.5 kJmol-1 respectively. Are these values for the enthalpies of formation of nitrosobenzene derivatives consistent with each other The first comparison considers the difference of the enthalpies of formation of nitroso and nitro compounds, ArNO and ArN02, 547 (Ar NO, NO2) ... 

Nitropropanoyl esters of glucose from the roots of Lotus pendunculatus Cav. were determined by analysis of nitrate released on alkaline hydrolysis. This method was validated for quantitation of both total nitro compounds in ethanolic extracts and for individual components from TLC separations557. 

The anion-radicals from aromatic nitro compounds preserve the second-order axis of symmetry. The analysis of superfine structure of the ESR spectrum of the nitrobenzene anion-radical reveals equivalency of the ortho and meta protons (Ludwig et al. 1964, Levy and Myers 1965). With the anion-radical of nitrosobenzene, the situation is quite different. This was evidenced from the ESR data (Levy and Myers 1965, Geels et al. 1965). Following electron transfer, the bent nitroso group fixes in the plane of the benzene ring to a certain extent. This produces five different types of protons, since both meta and ortho protons become nonequivalent. The nonequivalence of the ortho and meta protons has also been established for the anion-radicals of acetophenone (Dehl and Fraenkel 1963) and 5-methylthiobenzoate (Debacher et al. 1982 Scheme 6.17). 

Where the target analyte contains heteroatoms such as nitrogen, phosphorus and sulfur, atom-selective detectors can provide an ideal detection method. A number of examples appear in the literature of the use of a detector called a thermal energy analyser (TEA) for the measurement of A-nitroso compounds [14-17] and aromatic nitro compounds [18]. This has also been used as an HPLC detector [19, 20], and a modified TEA has been reported to be useful for analysis of amines and other nitrogen-containing compounds [17]. Unfortunately, this technique appears not to have gained in popularity, since no reports have appeared in the literature for over two decades. 

The few methods located for analysis of nitro compounds in air have not been well characterized for 1,3-DNB or 1,3,5-TNB. Only one method considered the analysis of 1,3-DNB specifically. The remainder were for analysis of nitrobenzene but could also be applied to the analysis of 1,3-DNB or... 

Archer, M. C. Tannenbaum, S. R. Wishnok, J. S. Nitro-samine formation in the presence of carbonyl compounds. In Walker, E. A. Bogovski, P. Griciute, L., Eds. "Environmental N-Nitroso Compounds. Analysis and Formation" lARC Scientific Publication No. 14 International Agency for Research on Cancer Lyon, France, 1976 pp. 141-145. 

Figure 27.18 Common configuration for postcolumn reactors with electrochemical analysis. (A) LC-chemical reaction-EC. Postcolumn addition of a chemical reagent (for example, Cu2+ or an enzyme). (B) LC-enzyme-LC. Electrochemical detection following postcolumn reaction with an immobilized enzyme or other catalyst (for example, dehydrogenase or choline esterase). (C) LC-EC-EC. Electrochemical generation of a derivatizing reagent. The response at the second electrode is proportional to analyte concentration (for example, production of Br2 for detection of thioethers). (D) LC-EC-EC. Electrochemical derivatization of an analyte. In this case a compound of a more favorable redox potential is produced and detected at the second electrode (for example, detection of reduced disulfides by the catalytic oxidation of Hg). (E) LC-hv-EC. Photochemical reaction of an analyte to produce a species that is electrochemically active (for example, detection of nitro compounds and phenylalanine). Various combinations of these five arrangements have also been used. [Reprinted with permission from Bioanalytical Systems, Inc.]...

Merritt, Jr, Applications of Pyrolysis GC/MS in the Analysis of Organic Nitro Compounds , Proc 23rd Annual Conf on MS Allied Topics,... 

Hess et al, Automated System for Analysis of Nitro Compounds in Water , BullEnvironContam-Toxicol 13 (5), 579-81 (1975) 128) R.J. 

Nitro compounds, labelled with carbon-14, have been used during the polymerization of styrene (40). It has been shown that picric acid, which is rather an inefficient inhibitor, formally resembles p benzoquinone with this monomer. It becomes incorporated in the polymer but most of it is included in polystyrene of comparatively low molecular weight. Most of the combined picric add can subsequently be removed by treatment with trifluoro-acetic anhydride reagent, showing that the picric acid is not held in the polymer by carbon-carbon bonds. Further, it was shown, by isotope dilution analysis, that most of the picric add removed from the polymer by this treatment appeared as the add. 

The anion radicals from aromatic nitro compounds preserve the second-order axis of symmetry. The analysis of the superfine structure of the ESR spectrum of the nitrobenzene anion radical reveals equivalency of the ortho and me la protons (Ludwig et al. 1964 Levy Myers 1965). 

Wardman P, Dennis MF, Everett SA, Patel KB, Stratford MRL, Tracy M (2003) Radicals from one-electron reduction of nitro compounds, aromatic N-oxides and quinones the kinetic basis for hypoxia-selective, bioreductive drugs. Biochem Soc Symp 61 171-194 Warman JM, de Haas MP, Hummel A, van Lith D, VerberneJB, Loman H (1980) A pulse radiolysis conductivity study of frozen aqueous solutions of DNA. Int J Radiat Biol 38 459-459 Warman JM, de Haas MP, Rupprecht A (1996) DNA a molecular wire Chem Phys Lett 249 319-322 Warters RL, Lyons BW (1992) Variation in radiation-induced formation of DNA double-strand breaks as a function of chromatin structure. Radiat Res 130 309-318 Warters RL, Hofer KG, Harris CR, Smith JM (1977) Radionuclide toxicity in cultured mammalian cells Elucidation of the primary site of radiation damage. Curr Top Radiat Res Q 12 389-407 Weiland B, Huttermann J (1998) Free radicals from X-irradiated, dry and hydrated lyophilized DNA as studies by electron spin resonance spectroscopy analysis of spectral components between 77 K and room temperature. Int J Radiat Biol 74 341-358 Weinfeld M, Soderlind K-JM (1991) 32P-Postlabeling detection of radiation-induced DNA-damage identification and estimation of thymine glycols and phosphoglycolate termini. Biochemistry 30 1091-1097... 

Substitutions by the SRn 1 mechanism (substitution, radical-nucleophilic, unimolecular) are a well-studied group of reactions which involve SET steps and radical anion intermediates (see Scheme 10.4). They have been elucidated for a range of precursors which include aryl, vinyl and bridgehead halides (i.e. halides which cannot undergo SN1 or SN2 mechanisms), and substituted nitro compounds. Studies of aryl halide reactions are discussed in Chapter 2. The methods used to determine the mechanisms of these reactions include inhibition and trapping studies, ESR spectroscopy, variation of the functional group and nucleophile reactivity coupled with product analysis, and the effect of solvent. We exemplify SRN1 mechanistic studies with the reactions of o -substituted nitroalkanes (Scheme 10.29) [23,24]. 

S3S) Camera, E., Pravisani, D., Ohman, V. Gas-liquid chromatographic analysis of mixtures of nitric esters with nitro compounds. Explosivstoffe 13, 237 (1965). —... 

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