Solid phase oxidations

Composite proplnts, which are used almost entirely in rocket propulsion, normally contain a solid phase oxidizer combined with a polymeric fuel binder with a -CH2—CH2— structure. Practically speaking AP is the only oxidizer which has achieved high volume production, although ammonium nitrate (AN) has limited special uses such as in gas generators. Other oxidizers which have been studied more or less as curiosities include hydrazinium nitrate, nitronium perchlorate, lithium perchlorate, lithium nitrate, potassium perchlorate and others. Among binders, the most used are polyurethanes, polybutadiene/acrylonitrile/acrylic acid terpolymers and hydroxy-terminated polybutadienes... 

Salacinski, P. R. P, McLean, C., Sykes, J E. C, Clement-Jones, V. V, and Lowry, P. J (1981) Iodmation of proteins, glycoproteins, and peptides using a solid-phase oxidizing agent, l,3,4,6,-tetrachloro-3a,6a-diphenyl glycolunl (iodogen). Anal. Biochem. 117, 136—146. 

Sodium permanganate, commercially available although more expensive than potassium permanganate (14), was found to be an even more potent oxidant. The monohydrate form (NaMnO. H.O) can be used as purchased to oxidize a variety of functionalities by stirring the solid with substrates dissolved in hexane or methylene chloride (Table II). The solid phase oxidation would seem particularly useful for small-scale reactions (< 1 gram substrate). 

At present we do not understand most aspects of the solid phase oxidations the need for trace quantities of water, Cu" catalysis, RCOOH inhibition, cation dependence, reaction selectivity, crystal deterioration, intermediates and mechanism. It is a case of a field in its infancy. We will clearly need to examine spectrometrically the permanganate surface while a reaction is in progress if we are to learn the secrets of reactivity on this crystalline solid (15). 

There are several reasons why the ability to reduce humic substances could be an advantage to metal-respiring microorganisms. Higher rates of reduction should be possible with humic acids and other soluble oxidants than with solid-phase oxidants that require the organism to continually establish physical contact in order to access fresh oxide surfaces. Humic substances are ubiquitous and accumulate to levels that could make them significant alternative electron acceptors in some ecosystems. As with other anaerobic electron acceptors, the capacity to support respiration is enhanced by processes that regenerate humic... 

Mechanism. No single mechanism explains the action of all fire retardants, so they probably work through a combination of several mechanisms. The mechanisms of fire retardants in wood involve a complex series of simultaneous reactions whose products may affect subsequent reactions. Pyrolysis of cellulose involves dehydration, depolymerization, decarbonylation, decomposition of smaller compounds, condensation, and other reactions. These pyrolysis reactions occur both in the solid phase and vapor phase. Addition of fire retardants will alter the reactions however, this alteration will depend on the additives, the material, and the thermal-physical environment. The presence of oxygen adds subsequent and competitive oxidation reactions to the above series. These oxidative reactions can take place in both the solid and vapor phases. Evidence indicates that most fire retardants reduce combustible volatiles production and limit combustion to the solid phase. The best retardants also inhibit solid-phase oxidation to effectively remove the fuel from the fire. 

The batch precipitation tests show dramatic effects of adipic acid slurry concentration and solid phase oxidation fraction on coprecipitation of adipic acid in scrubber solids. Real world scrubbers would probably never operate at adipic acid concentrations as high as those tested and would also not likely ever produce pure phase calcium sulfite hemihydrate. Therefore, the magnitude of the results observed is somewhat a product of the laboratory test conditions. The results do, however, establish the potential importance of adipic acid coprecipitation and, hence, the need for analysis of scrubber solids for adipic acid when determining adipic acid chemical degradation rates by a mass balance calculation approach. 

Fig. 8.17 Biogeochemical profiles of sulfur, manganese and iron species in a coastal marine sediment (Aarhus Bay, Denmark, 16 m water depth). A) Oxygen and nitrate profiles measured with and NO microsensors. B) Pore water profiles of dissolved manganese, iron and H S. C) Profiles of solid phase oxidized manganese and iron and of pyrite. D) Distribution of sulfate reduction rates (SRR) measured hy S-technique. The broken line at 4 cm depth indicates the transition between the suboxic zone and the sulfidic zone. Data in A) were measured at the same site but a different year than data in B)-D). (Data from Kjaer 2000 and Thamdrup et al. 1994a reproduced from Jorgensen and Nelson 2004).

The charge and discharge cycles of nickel batteries involve two different pairs of solid phases. Oxidation of p-Ni(OH)2 produces p-NiOOH, oxidation of a-Ni(OH)2 produces y-NiOOH. The end-products of these cycles are interconnected by dehydration and overcharge. For the crystallographic properties of Ni(II) hydroxides and Ni(Ill, IV) hydroxides see Section V.3.2.2.1 and Sections V.3.2.3.1, V.3.2.3.2, respectively. 

Salacinski, R, et al. (1981). Iodination of Proteins, Glycoproteins, and Peptides Using a Solid Phase Oxidizing... 

A solid-phase oxidative method for the conversion of 1,4-dihydropyridines to pyridines in good yields (76 90%) was carried out by employing phenyliodine(III) Z)w(trifluoroacetate) (FIFA) at room temperature. The dealkylation at the 4-position in the case of ethyl-, isopropyl-, and benzyl-substituted dihydropyridine derivatives with FIFA was circumvented by using elemental sulfur in solvent-free conditions under MWI for 5-7 min, compared to 3 5 min for the traditional heating to yield products 155 and 156 in 68% and 85% yields, respectively (Scheme 34) (99JCS(F1)1755). 

No such investigations have been performed for aromatic heterochain polymers (AHP). Thus there are many unclear and doubtful aspects in understanding the degradation mechanism. Studies performed at G. Petrov Research Institute for Plastics (Moscow) and Research and Production Company Polyplastic (Moscow) over the last 15 years concerning APH ageing and stabilisation, have been analysed. Specific features of high-temperature oxidation (300-400 °C) in melt and solid-phase oxidation (150-200 °C) of APH have been investigated. 

PDI extraction requires synchronisation of the oxidative process in neighbouring methylene chains, separated by a polymellitimide fragment. Random chain initiation and transmission would cause the occurrence of a series of oligomers in products of solid-phase oxidation. 

TPA amide is formed by thermo-oxidation in melt and at low-temperature solid-phase oxidation. Light yellow crystals of TPA amide and TPA mixture occur and accumulate on the surface of mould samples during accelerated heat ageing at temperatures of 150-200 °C. TPA is a typical product of hydrolysis by macrochain ends. From our point of view, TPA amide product is of greater interest. Recall that analogous products (relative to polymer structure) were already observed in investigation of thermo-oxidative transformations of other APH. For example, pyromellite diimide, was identified in thermooxidation of PAI [7, 21] and classical polyimide Capton , and 2,2 -(l,4-phenylene)-bis-(phenylpyrazine), is formed by poly(phenylquinoxaline) ageing [7]. 

PPQ, and other APH, thermo-oxidation of which are decelerated by addition of [11] and PCA. For example, addition of anilidophosphoric acid diphenyl ether and CUSO4 was found the most effective in polyimide (PI) and poly(alkene imide) (PAI) [7,21]. Use of PI and PAI as additives decelerate O2 absorption in PPA-2 at the solid-phase oxidation noticeably more effectively, than phenolic antioxidants. Efficiency of the additives is also noticeable at high temperatures, at which phenols are inefficient. 

Reproduced from Nlldshin Gl, Sokova LL, Makhaev VD, Kapustina Nl. Solid-phase oxidative halodecarboxylation of fi-arylacrylic acids with the ceric ammonium nitrate-alkali halide system. Russ Chem Bull Int Ed 2008 57 118-23, with permission of Springer. 

The mechanism of solid-phase oxidation, in particular, the oxidation of polymers has been still less investigated. Work in this field has begun comparatively recently. 

Several references have appeared on the use of solid-phase oxidants. Solid potassium permanganate-copper sulphate mixtures oxidize secondary alcohols to ketones in high yield, and pyridinium chromate or chromic acid on silica gel are described as convenient off-the-shelf reagents for oxidation of both primary and secondary alcohols. Anhydrous chromium trioxide-celite effects similar transformations only when ether is present as co-solvent. An excellent review, with over 400 references, on supported oxidants covers the use of silver carbonate-celite, chromium trioxide-pyridine-celite, ozone-silica, chromyl chloride-silica, chromium trioxide-graphite, manganese dioxide-carbon, and potassium permanganate-molecular sieve. 

Mn and Fe oxyhydroxides provide an important source of solid phase oxidants in natural materials and their reduction by anaerobic landfill leachate has been correlated with the increased biotransformation of XOMs... 

According to [5], they approach zero. Generally speaking, one of the features of the solid-phase oxidation is high E value of macroradical recombination. For instance, E of the second degree recombination of peroxy radicals reaches 50 - 100 kJ/mol [11, pp. 64, 69]. However, it is also known that PO recombination mechanism is superimposed with migration of free valences. Intensification of molecular movements due to plasticization or transition to amorphous systems causes an abrupt decrease of to 10 - 20 kJ/mol [11, p. 64]. These values are typical of transfers in liquids [6, p. 81]. In the present case, oxidation proeeeds in the polymer melt, i.e. molecular movements are unfrozen. Moreover, macroradical... 

As described in [1 - 11], the solid-phase oxidation is developed from the surface with oxygen penetration inside the sample. Table 9 shows assessments of oxidized l er thiekness at application of various stabilization systems. 

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