Decomposition process

Metastable Peaks. If the mass spectrometer has a field-free region between the exit of the ion source and the entrance to the mass analyzer, metastable peaks m may appear as a weak, diffuse (often humped-shape) peak, usually at a nonintegral mass. The one-step decomposition process takes the general form ... 

Several commercial grades are available fine crystals of 99 to 100% purity, large crystals, pressed lumps, rods, and granular material. Double-Decomposition Methods. Double-decomposition processes all iavolve the reaction of sodium chloride, the cheapest chlorine source, with an ammonium salt. The latter may be suppHed directiy, or generated in situ by the reaction of ammonia and a supplementary iagredient. Ammonium chloride and a sodium salt are formed. The sodium salt is typically less soluble and is separated at higher temperatures ammonium chloride is recovered from the filtrate by cooling. 

Other siinjlai structures undergo the following photofragmentation reartangement decomposition processes ... 

Sylvinite is removed from the ponds with scraper-loaders and hauled to a central pit. The salts are then transported to the refinery in a slurry line. KCl is separated from the NaCl by flotation. The flotation process is standard throughout the industry and is the same process used to separate KCl from impurities in a camaUite decomposition process explained later. An amine collector is used as one of the reagents. 

In solution, chlorine dioxide decomposes very slowly at ambient temperatures in the dark. The primary decomposition process is hydrolysis of chlorine dioxide into chlorite and chlorate ions. The hydrolysis rate is a function of the concentration of hydroxyl ions and temperature, proceeding rapidly at solution pH values above 10 ... 

A catalyst is defined as a substance that influences the rate or the direction of a chemical reaction without being consumed. Homogeneous catalytic processes are where the catalyst is dissolved in a liquid reaction medium. The varieties of chemical species that may act as homogeneous catalysts include anions, cations, neutral species, enzymes, and association complexes. In acid-base catalysis, one step in the reaction mechanism consists of a proton transfer between the catalyst and the substrate. The protonated reactant species or intermediate further reacts with either another species in the solution or by a decomposition process. Table 1-1 shows typical reactions of an acid-base catalysis. An example of an acid-base catalysis in solution is hydrolysis of esters by acids. 

Upon thermolysis of xanthates (xanthogenates) 1 olefins 2 can be obtained, together with gaseous carbon oxysulfide COS 3 and a thiol RSH 4. This decomposition process is called the Chugaev reactionanother common transcription for the name of its discoverer is Tschugaejf. 

The compound NaTa02F2 was found in treated mixtures that contained a higher concentration of Ta02F. The formation of this compound can be explained by the following decomposition process ... 

The formation of MNb02F2 serves as a source for the following decomposition process, which yields metaniobate of the alkali metal, MNb03 ... 

The MNbOF4 formed in the interaction described by Equation (92) then participates again in the decomposition processes described by Equations (90) and (91). 

Decomposition processes of oxyfluorides, in which two compounds are formed, one with a higher oxygen content than the precursor and the other with a lower oxygen content, seem to be common among oxyfluoroniobates. In general, this reaction can be represented as follows ... 

The fluorination process aims to decompose the material and convert tantalum and niobium oxides into complex fluoride compounds to be dissolved in aqueous solutions. The correct and successful performance of the decomposition process requires a clear understanding of the oxygen-fluorine substitution mechanism of the interaction itself. 

The decomposition process can be significantly intensified by the mechanical activation of the material prior to chemical decomposition. Based on a thermodynamic analysis of the system, Akimov and Chernyak [452] showed that the mechanical activation initiates dislocations mostly on the surface of the grains, and that heterogeneities in the surface cause the predominant migration of iron and manganese to the grain boundaries. It is noted that this phenomenon is more pronounced for manganese than it is for iron. 

At even higher temperatures - 80°C for (NH4)3Nb08 and 90°C for (NH4)3Ta08 -the decomposition process becomes explosive [512]. 

Unidentified Inhibitors. Many reports have been published relative to inhibitory responses which were obtained with extracts of plant tissue or from products associated with decomposition processes. For the most part, the inhibitory responses have been noted, but the inhibitors have not been identified chemically. Garb 48) tabulated approximately 25 references in which inhibitors were reported but were not characterized. These will not be relisted here. Uncharacterized inhibitors have also been reportd by Le Tourneau et al. 91), Patrick and Koch 112), Lapusan 85), Guenzi and Mc-Calla 63), Lawrence and Kilcher 86), Grodzinskii et al. 60), Brown 24), Patrick et al. 114), and Hoveland 73). 

It lias also been suggested that photoexcited benzoyl peroxide is somewhat more susceptible to induced decomposition processes involving electron transfer than the ground state molecule. Rosenthal et c//.15 reported on redox reactions with certain salts (including benzoate ion) and neutral molecules (e.g. alcohols). 

The basic approach taken in the analytical studies of composite-propellant combustion represents a modification of the studies of double-base propellants. For composite propellants, it has been assumed that the solid fuel and solid oxidizer decompose at the solid surface to yield gaseous fuel and oxidizing species. These gaseous species then intermix and react in the gas phase to yield the final products of combustion and to establish the flame temperature. Part of the gas-phase heat release is then transferred back to the solid phase to sustain the decomposition processes. The temperature profile is assumed to be similar to the situation associated with double-base combustion, and, in this sense, combustion is identical in the two different types of propellants. 

Constant rate thermo gravimetry has been described [134—137] for kinetic studies at low pressure. The furnace temperature, controlled by a sensor in the balance or a pressure gauge, is increased at such a rate as to maintain either a constant rate of mass loss or a constant low pressure of volatile products in the continuously evacuated reaction vessel. Such non-isothermal measurements have been used with success for decomposition processes the rates of which are sensitive to the prevailing pressure of products, e.g. of carbonates and hydrates. 

Systems for consideration under this heading are conveniently classified into two groups, distinguished by the relationship existing between the reactant and the additive considered, which may be (i) a product of the decomposition process or (ii) a substance chemically different from all the participating phases. In certain important respects, reactions of type (i) may be regarded as specific instances of the autocatalytic behaviour characteristic of the reactant-derived product in many nucleation and... 

The hydrolysis of Pu+lt can result in the formation of polymers which are rather intractable to reversal to simpler species. Generally such polymerization requires [Pu] > 10-8 M but, due to the irreversibility, dilution of more concentrated hydrolysis solutions below this value would not destroy the polymers. The rate of polymerization has been found to be third order in Pu concentrations and has a value of 5.4 X 10-5 moles/hr at 50°C and [Pu+I ]T t 0.006 M, [HNO3] s o.25 M (13). Soon after formation, such polymers can be decomposed readily to simple species in solution by acidification or by oxidation to Pu(Vl). However, as the polymers age, the decomposition process requires increasingly rigorous treatment. The rate of such irreversible aging varies with temperature, Pu(IV) concentration, the nature of... 

Intramolecular isotope effects were studied in the systems N2-HD, CO-HD, 02-HD and C02-HD (20). Product decomposition directly associated with rupture of OH or OD bonds was not observed in these reactions. Isotope effects in decomposition processes which gave OH + or OD+ from reactions of 02+ with HD and COH+ or COD + from... 

Correlated or geminate radical pairs are produced in unimolecular decomposition processes (e.g. peroxide decomposition) or bimolecular reactions of reactive precursors (e.g., carbene abstraction reactions). Radical pairs formed by the random encounter of freely diffusing radicals are referred to as uncorrelated or encounter (P) pairs. Once formed, the radical pairs can either collapse, to give combination or disproportionation products, or diffuse apart into free radicals (doublet states). The free radicals escaping may then either form new radical pairs with other radicals or react with some diamagnetic scavenger... 

The mechanism shown in Scheme 6 is, for the most part, consistent with points (1) to (9). Thus, initially formed is a o--complex that is stable only at low temperatures. Upon matrix warm-up, a caged, radical pair forms and, if the R portion possesses a sufficient excess of vibrational energy, decomposition processes may occur. The radicals combine to form RPdX, which may, or may not, be isolated. 

Influence of OH concentration on the reaction rate constant. From the dependence of the observed first order rate constant on the sodium hydroxide concentration, shown in Table 3, it can be established that equation (2) holds, where ko represents the contribution due to the unimolecular decomposition process and koH is the contribution due to the base-catalysed process in alkaline medium. 

It should be noted that the absence of a proton in the a position in the case of N-Br-aminoisobutyric acid makes unoperative its decomposition to form an a-ketoacid, and the slight increase in the observed reaction rate constant upon increasing the NaOH concentration can be attributed to a secondary decomposition process, probably leading to the formation of an hydrazine (refs. 22 - 24). 

Influence of ionic strength on the reaction rate constant. The influence of the ionic strength on the reaction rate constant was studied using KCl as electrolyte. The results obtained in this study are listed in Table 4, where we can see that the reaction rate constant for N-Br-alanine decomposition undergoes an increment of 40 % upon changing the ionic strength from 0.27M to IM, while in the case of N-Bromoaminoisobutyric acid the increment of the reaction rate constant is of about 12 %. This is an evidence of a non ionic mechanism in the case of the decomposition of N-Br-aminoisobutyric acid, as it is expected for a concerted decarboxylation mechanism. For the decomposition of N-Br-proline the increase on the reaction rate constant is about 23 % approximately, an intermediate value. This is due to the fact both paths (concerted decarboxylation and elimination) have an important contribution to the total decomposition process. 

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