Carbonate species reaction with

Xie and Bell (2000) used a Raman cell that was a reactor to identify the carbon-containing species on the surface of zirconia during the synthesis of dimethyl carbonate from C02 and methanol. The results showed that surface methoxides and surface carbonates formed from monomethyl carbonate species that yield dimethyl carbonate upon reaction with methanol. 

In freshwaters, where the Br concentrations are typically far lower, -OH may react either with bicarbonate, carbonate, or dissolved organic matter, depending on the relative concentrations of these species. Reactions with bicarbonate and carbonate produce either the bicarbonate radical, -HCOs, or the carbonate radical anion, COj the pKa of the acid form is about 7.6 (Eriksen et al., 1985). 

P.V. Kortunov, M. Siskin, L.S. Baugh, D.C. Calabro, In situ nuclear magnetic resonance mechanistic studies of carbon dioxide reactions with liquid amines in Non-aqueous systems evidence for the formation of carbamic acids and zwitterionic species. Energy Fuels 29 (9) (2015) 5940-5966. 

SSITKA. The idea behind this approach was to compare the time response of isotopically labelled surface and gas-phase species by DRIFT spectroscopy and MS analysis. This novel technique was applied for mechanistic analysis water-gas shift (WGS) and reversed WGS reactions over F t- and Au-based catalysts with the aim of identifying true surface intermediates. These authors found that both formate and carbonate species labelled with C were formed on the catalyst surface after switching from C0/H20/Ar = 2/7/91 to C0/H20/A = 2/7/91. In order to determine which surface species actively participated in CO2 formation, they compared temporal changes in the IR bands of these surface species with those of gas-phase C02. Since the rate of CO2 formation was ca. 60 times higher than the rate of the exchange of formate species it was concluded that the formates detected by DRIFT spectroscopy could not be the main surface intermediates of gas-phase CO2. However, the role of surface formates in CO2 production may change with rising temperature as demonstrated in Ref. 129 where the formate species were spectators at 160°C but became main reaction intermediates at 220 C. 

Once the radicals diffuse out of the solvent cage, reaction with monomer is the most probable reaction in bulk polymerizations, since monomers are the species most likely to be encountered. Reaction with polymer radicals or initiator molecules cannot be ruled out, but these are less important because of the lower concentration of the latter species. In the presence of solvent, reactions between the initiator radical and the solvent may effectively compete with polymer initiation. This depends very much on the specific chemicals involved. For example, carbon tetrachloride is quite reactive toward radicals because of the resonance stabilization of the solvent radical produced [1] ... 

Quantitative Analysis of All llithium Initiator Solutions. Solutions of alkyUithium compounds frequentiy show turbidity associated with the formation of lithium alkoxides by oxidation reactions or lithium hydroxide by reaction with moisture. Although these species contribute to the total basicity of the solution as determined by simple acid titration, they do not react with allyhc and henzylic chlorides or ethylene dibromide rapidly in ether solvents. This difference is the basis for the double titration method of determining the amount of active carbon-bound lithium reagent in a given sample (55,56). Thus the amount of carbon-bound lithium is calculated from the difference between the total amount of base determined by acid titration and the amount of base remaining after the solution reacts with either benzyl chloride, allyl chloride, or ethylene dibromide. 

The reaction is proposed to proceed from the anion (9) of A/-aminocatbonylaspattic acid [923-37-5] to dehydrooranate (11) via the tetrahedral activated complex (10), which is a highly charged, unstable sp carbon species. In order to design a stable transition-state analogue, the carboxylic acid in dihydrooronate (hexahydro-2,6-dioxo-4-pyrimidinecarboxylic acid) [6202-10-4] was substituted with boronic acid the result is a competitive inhibitor of dibydroorotase witb a iC value of 5 ]lM. Its inhibitory function is supposedly due to tbe formation of tbe charged, but stable, tetrabedral transition-state intermediate (8) at tbe active site of tbe enzyme. 

A dication derived from 1,3,5,7-tetramethylcyclooctatetraene is formed at —78 C in SO2CI by reaction with SbFj. Both the proton and carbon NMR spectra indicate that the ion is a symmetrical, diamagnetic species, and the chemical shifts are consistent with an... 

The silyl group directs electrophiles to the substituted position. That is, it is an ipso-directing group. Because of the polarity of the carbon-silicon bond, the substituted position is relatively electron-rich. The ability of silicon substituents to stabilize carboca-tion character at )9-carbon atoms (see Section 6.10, p. 393) also promotes ipso substitution. The silicon substituent is easily removed from the c-complex by reaction with a nucleophile. The desilylation step probably occurs through a pentavalent silicon species ... 

Vapor-grown carbon fibers have been prepared by catalyzed carbonization of aromatic carbon species using ultra-fine metal particles, such as iron. The particles, with diameters less than 10 nm may be dispersed on a substrate (substrate method), or allowed to float in the reaction chamber (fluidized method). Both... 

Cp(CO)2Re(THF) forms the complex 105 upon reaction with thiophene (89JA8753, 910M2436). Similar species are known for 2- and 3-methyl-, 2,5-dimethyl, and tetramethylthiophene (91IC1417). Thiophene in 105 is S-coordi-nated, and the sulfur atom is pyramidal. Treatment of 105 with Fc2(CO)9 produces 106, where the thiophene ligand is bridge-coordinated via the sulfur atom to rhenium and four carbon atoms of the dienic system with iron (the coordination mode). The pyramidal nature of the sulfur atom is preserved. The -coordination of thiophene separates the dienic and sulfur counterparts of the ligand and decreases the TT-electron delocalization, which leads to the enhanced basicity of the sulfur atom. 

The initial step is the protonation of the aldehyde—e.g. formaldehyde—at the carbonyl oxygen. The hydroxycarbenium ion 6 is thus formed as reactive species, which reacts as electrophile with the carbon-carbon double bond of the olefinic substrate by formation of a carbenium ion species 7. A subsequent loss of a proton from 7 leads to formation of an allylic alcohol 4, while reaction with water, followed by loss of a proton, leads to formation of a 1,3-diol 3 " ... 

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