Vibrational spectroscopy hydroperoxides

Many methods have been developed to access the extent of oxidative deterioration, which are related to the measurement of the concentration of primary or secondary oxidation products or of both. The most commonly used are peroxide value (PV) that measures volumetrically the concentration of hydroperoxides, anisidine value (AV), spectrophotometric measurement in the UV region and gas chromatographic (GC) analysis for volatile compounds. Vibrational spectroscopy, because of its high content in molecular structure information, has also been considered to be useful for the fast measurement of lipid oxidation. In contrast to the time consuming chromatographic methods, modem techniques of IR and Raman spectrometry are rapid and do not require any sample preparation steps prior to analysis. These techniques have been used to monitor oil oxidation under moderate and accelerated conditions and the major band changes have been interpreted. ... 

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... 

NMR spectroscopy, 694-5 vibrational spectra, 692 X-ray diffraction, 695-6 synthesis, 309-51 tertiary, 690-1 theoretical aspects, 67-84 thymine ozonolysis, 616 see also Chiral hydroperoxides DNA... 

Poly(vinylferrocenium perchlorate). Hydroperoxide biosensor, 688 POM (polyoxometaUates), 429-30, 1057 POP (persistent organic pollutants), 747 Poppyseed oil, vibrational spectra, 692 Porphyrin, O NMR spectroscopy, 185 Potassium carbonate, alcohol oxidation, 492 Potassium hexacyanoferrate(II), hydrogen peroxide biosensor, 653 Potassium hydrogen phthalate hemiperhydrate, 98-100... 

The primary product of oxidation is the hydroperoxide group and analysis of peroxide formation is an important feature of many studies. The most commonly used methods take advantage of the ability of hydroperoxides to oxidize either iron (II) or iodide ions in acidic solutions (138,139). They can be extremely sensitive but are time consuming and require very careful control to avoid problems from adventitious oxidation of solvents. In principle, hydroperoxides are detectable by ir spectroscopy, but their characterization is complicated by the broad absorption due to hydrogen bonding interaction with other hydroperoxides and with —OH groups, and the overlap with —OH vibrations. Studies of hydroperoxides in PP using CPMAS nmr spectroscopy on C-enriched polymer have been reported (140). 

---