Ethylene ions, decomposition

In the 20 eV El mass spectrum of CHD = CHD and CD2CDH, the isotope effects IhJIhd and IHd/Id2 were found to be 1.76 and 1.53, respectively [331]. With the metastable ion decompositions, isotope effects of about 30 were obtained [331, 645]. Isotope effects on loss of molecular hydrogen from all ethylene isomers have been recently... 

Intermolecular isotope effects /c2h4 //c2d4 in the range 1.3 -1.9 have been reported for metastable ion decompositions effecting loss of ethylene from various triazole molecular ions with 7V-ethyl side chains [568, 573]. Subsequent elimination of N2 from the benztriazole fragment ions occurs with an isotope effect of 1.5 (unlabelled vs. perdeuterated ions), perhaps indicating that a hydrogen transfer is involved in the decomposition [573],... 

The radiolysis product yields in the presence of ion scavenger (Table III) also show that ethane is not formed from neutralization of stable ions. Therefore, the remainder of the ethane product (above that indicated to result from neutral decomposition) must be produced by an ion-molecule process—i.e., a yield of G = 1.47. The ion-molecule reactions previously listed show that ethylene ions react with ethyl chloride to form ethane. From the relative rates indicated for Reactions 3a-3d and the ethane yield just derived, a relative yield of 2.46 may be deduced for the ionic fragmentation to ethylene ion in the radiolysis. 

An analogous question arises to that discussed in the case of acetylene concerning whether these products result from the decomposition of C4Hg , C6Hi2, etc. reaction complexes, or whether the dissociation of the initial ion-molecule complex is so rapid that the C3H5 species initiates the reaction chain. Analogous experimental techniques using the tandem mass spectrometer were used to answer these questions for the reaction sequence in the ethylene-ion-ethylene system. 

The information on the characteristic ion decomposition times t < 10 s is rather limited. Experiments using ionization of complex molecules by electron impact in a relatively strong electric field [214] show that most ions in the mass spectra of ethylene, ethane, and hexane are formed in less than 10 s. However, fragment ions formed in a time > 10 s are observed in the mass spectra of hexane and toluene in considerable amounts. The characteristic decomposition times of and other ions [214, 461] include ... 

On the other hand, the formation of ethylene was ascribed mainly to the unimolecular decomposition of a neutral excited propane molecule. These interpretations were later confirmed (4) by examining the effect of an applied electrical field on the neutral products in the radiolysis of propane. The yields of those products which were originally ascribed to ion-molecule reactions remained unchanged when the field strength was increased in the saturation current region while the yields of hydrocarbon products, which were ascribed to the decomposition of neutral excited propane molecules, increased several fold because of increased excitation by electron impact. In various recent radiolysis 14,17,18,34) and photoionization studies 26) of hydrocarbons, the origins of products from ion-molecule reactions or neutral excited molecule decompositions have been determined using the applied field technique. However, because of recent advances in vacuum ultraviolet photolysis and ion-molecule reaction kinetics, the technique used in the above studies has become somewhat superfluous. 

The rate of peroxide decomposition and the resultant rate of oxidation are markedly increased by the presence of ions of metals such as iron, copper, manganese, and cobalt [13]. This catalytic decomposition is based on a redox mechanism, as in Figure 15.2. Consequently, it is important to control and limit the amounts of metal impurities in raw rubber. The influence of antioxidants against these rubber poisons depends at least partially on a complex formation (chelation) of the damaging ion. In favor of this theory is the fact that simple chelating agents that have no aging-protective activity, like ethylene diamine tetracetic acid (EDTA), act as copper protectors. 

The fact that only ethylene and tetramethylethylene are evolved from exp-[8]rotane 168 and permethyl-exp-[6]rotane 173 upon thermal decomposition leads to the conclusion that the spirocyclopropane moieties in these expanded [n]rotanes fragment only externally and leave carbene moieties behind. Indeed, the MALDI-TOF mass spectra of several exp-[ ]rotanes show fragment ions with M minus 28. Thus, if this fragmentation in an exp-[n]rotane were to continue n times, a cyclic C carbon cluster would be left over. So far, however, a fragment ion with m/z = 480 corresponding to 182 has not been recorded in the mass spectrum of exp-[8]rotane 168 and it remains to be seen whether a Cgo cluster 183 will be detected in the mass spectrum of exp-[12]rotane 171 (Scheme 35). 

In our experiment, photocatalytic decomposition of ethylene was utilized to probe the surface defect. Photocatalytic properties of all titania samples are shown in table 2. From these results, conversions of ethylene at 5 min and 3 hr were apparently constant (not different in order) due to the equilibrium between the adsorption of gaseous (i.e. ethylene and/or O2) on the titania surface and the consumption of surface species. Moreover it can be concluded that photoactivity of titania increased with increasing of Ti site present in titania surface. It was found that surface area of titania did not control photoactivity of TiOa, but it was the surface defect in titania surface. Although, the lattice oxygen ions are active site of this photocatalytic reaction since it is the site for trapping holes [4], this work showed that the presence of oxygen vacancy site (Ti site) on surface titania can enhance activity of photocatdyst, too. It revealed that oxygen vacancy can increase the life time of separated electron-hole pairs. 

Both Ag(ll) and Ag(III) have been considered to be the active species in the Ag(I)-catalysed oxidation of many compounds by persulphate ion. Salts of Ag(III) have been prepared but only a single kinetic study (of the decomposition of water by the ethylene dibiguanide nitrate) has been reported (p. 366). 

The removal of inorganic salts from reaction mixtures afforded by polymeric materials may be simply and effectively accomplished by dialysis,166 178 after decomposition of remaining periodate with ethylene glycol130 131 or butylene glycol. 161 170 Alternatively, the iodate and periodate ions may be removed as such, or after reduction to free iodine. The iodate and periodate ions have been effectively precipitated by means of sodium carbonate plus manganous sulfate,6 or by lead dithionate,191 barium chloride,24 192 193 strontium hydroxide194 202 or barium hydroxide,203 204 lead... 

We note finally that in view of the apparent fragmentation of parent species, it seems somewhat surprising that the low temperature ethylene desorption peak is not accompanied by a partial decline in the intensity of the C2H2 ion. In fact, the intensity of this ion appears to increase slightly in this region. We suggest that this is due to the formation of additional acetylenic complexes by decomposition of adsorbed ethylene upon heating. 

The major pathways for the fragmentation of kojic acid (81,5-hydroxy-2-hydroxymethyl-pyran-4-one), are shown in Scheme 14 support for each route was provided by the appearance of metastable ion peaks (67MI22203). An RDA cleavage followed by loss of a CH2OH radical produces ion (81a), m/e 69, the structure of which was substantiated by deuteration experiments. The ion at m/e 97 arises by extrusion of CO from the molecular ion and loss of HO- from the side chain structures (81b) and (81c) were proposed. Decomposition of [M]t occurs to give ethylene and an HC=0 fragment. The initial stage involves loss of a -CHO radical from the hydroxymethyl substituent, a process which has... 

Acrylic acid [79-10-7] - [AIR POLLUTION] (Vol 1) - [ALDEHYDES] (Vol 1) - [ALLYL ALCOHOL AND MONOALLYL DERIVATIVES] (Vol 2) - [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) - [POLYESTERS, UNSATURATED] (Vol 19) - [FLOCCULATING AGENTS] (Vol 11) - [CARBOXYLICACIDS - SURVEY] (Vol 5) -from acetylene [ACETYLENE-DERIVED CHEMICALS] (Vol 1) -from acrolein [ACROLEIN AND DERIVATIVES] (Vol 1) -acrylic esters from [ACRYLIC ESTER P OLYMERS - SURVEY] (Vol 1) -from carbon monoxide [CARBON MONOXIDE] (Vol 5) -C-21 dicarboxylic acids from piCARBOXYLIC ACIDS] (Vol 8) -decomposition product [MAT. ETC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) -economic data [CARBOXYLIC ACIDS - ECONOMIC ASPECTS] (Vol 5) -ethylene copolymers [IONOMERS] (Vol 14) -in floor polishes [POLISHES] (Vol 19) -in manufacture of ion-exchange resins [ION EXCHANGE] (V ol 14) -in methacrylate copolymers [METHACRYLIC POLYMERS] (Vol 16) -in papermaking [PAPERMAKING ADDITIVES] (Vol 18)... 

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