Mass spectroscopy peroxides

Within the cage, both fcrf-alkoxy and acryloxy radicals undergo side reactions. For example, tert-butoxy radicals d ompose to form acetone and methyl radicals while benzoyloxy radicals liberate carbon dioxide to form phenyl radicals. Fink [154] has studied the decomposition of benzoyl peroxide in benzene and analyzed the products using gas chromatography and mass spectroscopy. The three products produced were biphenyl (72%), phenyl cyclohexadiene (28%), and phenyl benzoate (0.3%). Using deuterated benzoyl peroxide, it was determined that these products arose from reaction with the benzene rather than radical combination within the cage. 

Pena-Quevedo, A.J. Cyclic organic peroxides identification and trace analysis by Raman microscopy and open-air chemical ionization mass spectroscopy. University of Puerto Rico, PhD thesis, Puerto Rico (2009)... 

NMR, mass spectroscopy, and various chromatographic techniques. Among the accelerated life tests used in fuel cell systems, Fenton s reagent, a combination of ferrous ions and aqueous hydrogen peroxide, is a well-known method for generating peroxide radicals at temperatures that mimic fuel cell operation (Fig. 2.30) [157],... 

Liquid and paper chromatographies as well as mass spectrometry (MS) are used for the identification and analysis of hydroperoxides [60]. Nuclear magnetic resonance (NMR) spectroscopy is used for identification of diacyl peroxides. 

Over the past decades several techniques have been used to obtain direct experimental information on the speciation of peroxo metal complexes heteronuclear NMR, IR and Raman spectroscopy, potentiometry and electrospray ionization mass spectrometry (ESI-MS). Often, more than one technique was used at the same time for acquiring complementary evidence. A significant, although nonexhaustive, list of examples related to several metals is given in Table 2. They include cases with hydrogen peroxide or alkyl... 

Conjugated dienes value (CDV), secondary oxidation products, 663, 671-2 Coordination compounds O NMR spectroscopy, 185 silyl peroxides, 808-10 Coordination ionospray mass spectrometry,... 

Dialkyl peroxides (continued) colorimetry, 707-8 flame ionization detection, 708 NMR spectroscopy, 708 titration methods, 707 UV-visible spectrophotometry, 707-8 enthalpies of reactions, 153-4 graft polymerization initiation, 706 hydroperoxide determination, 685 peroxide transfer synthesis, 824-5 stmctural characterization, 708-16 electrochemical analysis, 715-16 electron diffraction, 713 mass spectrometry, 714 NMR spectroscopy, 709-11 thermal analysis, 714-15 vibrational spectra, 713-14 X-ray crystallography, 711-13 synthesis... 

Final ozonides (FOZ), 716, 717, 718 cis and trans isomers, 719, 720 dialkyl peroxide formation, 706 IR spectroscopy, 719 mass spectrometry, 690 microwave spectroscopy, 721-3 molecular model, 750 NMR spectroscopy, 724-5 ozone water disinfection, 606 X-ray crystallography, 726-30 Fireflies... 

However, spectroscopic studies of activated BLM indicate that it is not an Fev=0 species. It exhibits an S - 1/2 EPR spectrum with g values at 2.26, 2.17, and 1.94 [15], which is typical of a low-spin Fe111 center. This low-spin Fem designation is corroborated by Mossbauer and x-ray absorption spectroscopy [16,19], Furthermore, EXAFS studies on activated BLM show no evidence for a short Fe—0 distance, which would be expected for an iron-oxo moiety [19], These spectroscopic results suggest that activated BLM is a low-spin iron(III) peroxide complex, so the two oxidizing equivalents needed for the oxidation chemistry would be localized on the dioxygen moiety, instead of on the metal center. This Fe(III)BLM—OOH formulation has been recently confirmed by electrospray ionization mass spectrometry [20] and is supported by the characterization of related synthetic low-spin iron(III) peroxide species, e.g., [Fe(pma)02]+ [21] and [Fe(N4py)OOH]2+ [22], The question then arises whether the peroxide intermediate is itself the oxidant in these reactions or the precursor to a short-lived iron-oxo species that effects the cytochrome P-450-like transformations. This remains an open question and the subject of continuing interest. 

Yates group [67] used IR spectroscopy, temperature-programmed desorption, and mass spectrometry to study Xe adsorption on purified and cut SWNTs. The nanotubes were cut by subjecting them to a mixture of sulfuric and nitric acid treatment, followed by sonication with sulfuric acid and peroxide. Infrared (IR) measurements determined the presence of carboxylic acid and quinone groups on the treated tubes. Mass spectrometry of treated tubes heated under vacuum determined the evolution of different groups from the tubes as the temperature increased (CH4, CO, H2, and CO2). 

Parkes and co-workers have also conducted H NMR studies on s5movial fluid from patients with rheumatoid arthritis. Tbe nature of the nontransferrin-bound iron in the synovial fluid of patients with inflammatory joint disease was investigated. Transferrin is an iron ion transport protein. In these patients the synovial fluid contains non-transferrin-bound iron which appears to be in low-molecular-mass, redox-active complexes of unknown type. This form of iron has the adverse effect of stimulating free-radical lipid peroxidations involving oxygen. 500 MHz spin-echo H NMR spectroscopy was used to show that the incubation of patient synovial fluid with the powerful Fe(III)... 

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