Chemiluminescence oxidation

Figure 4 Chemiluminescence oxidation runs at 140°C in oxygen for films of polypropylene (PP), polyamide 66 (PA 66) and polyethylene (PE) (logarithmic time scale).

Figure 5 Chemiluminescence oxidation runs for powder of poly(2,6-dimethyl-l,4-phenylene oxide) at different temperatures, oxygen (logarithmic time scale).

Figure 14 Chemiluminescence oxidation runs at 120°C in oxygen for polypropylene powder samples of different molar mass. The numbers against each curve express the average molar mass in g/mol. 

Figure 15 Chemiluminescence oxidation runs for polypropylene powder at different temperatures the average molar mass of the polymer is 180 kg/mol. 

In aprotic media, the chemiluminescent oxidation of luminol requires only oxygen and a strong base2 4. 

A still more complicated reaction is the chemiluminescent oxidation of sodium hydrogen sulfide, cysteine, and gluthathione by oxygen in the presence of heavy metal catalysts, especially copper ions 60>. When copper is used in the form of the tetrammin complex Cu(NH3) +, the chemiluminescence is due to excited-singlet oxygen when the catalyst is copper flavin mononucleotide (Cu—FMN), additional emission occurs from excited flavin mononucleotide. From absorption spectroscopic measurements J. Stauff and F. Nimmerfall60> concluded that the first reaction step consists in the addition of oxygen to the copper complex ... 

A still more complex reaction pattern underlies the oxidation of purpurogallin 12. The chemiluminescent oxidation of pyrogallol has been known for quite a long time. 

Fluorescence is by far the most important emission in hydrazide chemiluminescence the possible involvement of triplet-singlet transfer in some cases is discussed below. The correct chemical pathway can be understood to mean in part that a hydrazide must be stable enough under the oxidative reaction conditions usually applied to ensure that only a small proportion of the hydrazide molecules are consumed in non-chemiluminescent oxidation reactions, 3.6-diamino-phthalic hydrazide 24, for example, should yield a highly fluorescent dicarboxylate dianion and therefore exhibit strong chemiluminescence. However, being a derivative... 

The emission spectra match the fluorescence of the corresponding acid. Methane was detected as a major product in the chemiluminescent oxidation of 57 a and it was suggested that it resulted from the decomposition of methyl-diimine formed after dehydrogenation of the hydrazide 57a ... 

The bioluminescence of the American firefly (Photinus pyralis) is certainly the best-known bioluminescent reaction, thanks to the work of Me Elroy and coworkers and E. H. White and his group (for references see P, p. 138, 6,168,169)) The substrate of this enzyme-catalyzed chemiluminescent oxidation is the benzothiazole derivative 107 (Photinus luciferin) which yields the ketone 109 in a decarboxylation reaction. The concept of a concerted cleavage of a dioxetane derivative has been applied to this reaction 170> (see Section II. C.). Recent experiments with 18C>2 have challenged this concept, as no 180-containing carbon dioxide was detected from the oxidation of 107 171>. 

Sakamoto [243] determined picomolar levels of cobalt in seawater by flow injection analysis with chemiluminescence detection. In this method flow injection analysis was used to automate the determination of cobalt in seawater by the cobalt-enhanced chemiluminescence oxidation of gallic acid in alkaline hydrogen peroxide. A preconcentration/separation step in the flow injection analysis manifold with an in-line column of immobilised 8-hydroxyquinoline was included to separate the cobalt from alkaline-earth ions. One sample analysis takes 8 min, including the 4-min sample load period. The detection limit is approximately 8 pM. The average standard deviation of replicate analyses at sea of 80 samples was 5%. The method was tested and inter calibrated on samples collected off the California coast. 

Evidence is presented in support of free-radical mechanisms for the oxidation of ionizable carbon acids by oxidized flavin. Activation of molecular oxygen by reduced flavin is shown to occur through the formation of a 4a-hydroperoxyflavin that may, dependent upon conditions and substrate, transfer one or two oxygen atoms. Examples of all reactions are provided in the text. The present state of knowledge concerning the chemiluminescent oxidations of aldehydes by 4a-hydroperoxyfla-vin is considered. 

In addition to their implication as reactive intermediates in bioluminescence, dioxetanones have been proposed as key intermediates in several chemiluminescent systems. Most notable are the chemiluminescent oxidation reaction of acridan esters [19] and the chemiluminescent reaction of the related acridinium salts [20] (Rauhut et al., 1965a McCapra et al., 1977). Both reactions are quite efficient at generating singlet excited states (pCE = 10% and 2% respectively) and, owing to the elegant work of McCapra and others, are among the best understood complex chemiluminescent reaction mechanisms. 

Pseudobases have often been postulated as intermediates in the chemiluminescent oxidation of acridinium cations to acridinones.103-297 299 Both the mono- and dipseudobases (156 and 157) of lucigenin have been proposed as intermediates in the chemiluminescent oxidation of this cation in basic solutions. 

As in the case of horseradish peroxidase, several synthetic metalloporphyrins in the presence of H2O2 have been found to be potent catalysts for the chemiluminescent oxidation of luminol or isoluminol. The microperoxidases, mainly MP8 and MPll, have been shown to act as functional peroxidase enzyme models. " However, they are readily inactivated within one min of catalytic turnover, and incorporation into a molecular sieve... 

The autoxidation of 9-phosphono-9,10-dihydroacridanes (3) provided chemiluminescence which lasted enough to be spectroscopically detected, and whose emission spectra were in completely agreement with the fluorescence spectrum of the acridone anion generated from 5 under basic conditions. The formation of the weakly fluorescent 9-phosphonoacridine (7) accompanies these chemiluminescent oxidation reactions. 

Motoyoshiya J, Isono Y, Hayashi S, Kanzaki Y, Hayashi S, Chemiluminescent oxidation of phosphonates Phospha-l,2-dioxetanes as possible intermediates. Tetrahedron Lett 1994 35 5875-78. 

Nozaki O, Ji X, Kricka LJ. New enhancers for the chemiluminescent peroxidase catalysed chemiluminescent oxidation of pyrogallol and purpurogallin. J Biolumin Chemilumin 1995 10 151-6. 

Til. Thorpe, G. H. G., Kricka, L. J., Gillespie, E., Mosely, S., Amess, R., Baggett, N., and Whitehead, T. P., (1985). Enhancement of horseradish peroxidase catalyzed chemiluminescent oxidation of cyclic diacyl hydrazides by 6-hydroxybenzothiazole. Anal. Biochem. 145, 96-100 (1985). 

Freed and Faulkner (1972) have deduced that the monocation dimer of N-mcthylphenothiazine (N-MP) affects the yield of triplet states in the chemiluminescent oxidation of fluoranthene anion radical (FA -) by N-MP + [eqns (91) and (92)]. The triplet yields... 

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