Formate ion, from

The conditions of IC analysis (Table I) chosen were based on the need for separation of formate ion from common atmospheric contaminants, such as chloride ion, and other organic anions, such as acetate. The conditions were also optimized to obtain a suitable detection limit. Thus, a weak borate eluent (0.005 combined with a 500 mm anion separator column (and a 150 mm precolumn) was chosen. Conversion of the pre-column and separator column to their borate forms (from the normal carbonate form) was necessary. The process of continually passing the borate eluent through the columns until a stable baseline was obtained required several hours. 

The same workers have more recently used a similar catalyst system to produce formic acid (formate ion) from hydrogen and carbon dioxide (160). The catalyst system is again Pd(diphos)2 and Et3N in benzene solution under 25 atm each of C02 and H2. The reaction is run at room temperature or higher. A small amount of water dramatically accelerates the rate of the reaction, and a mechanism is proposed to account for this effect. Control experiments are stated to rule out the initial reduction of C02 to CO by H2, followed by reaction with water to yield the formic acid. 

The zeroth-order rates of nitration depend on a process, the heterolysis of nitric acid, which, whatever its details, must generate ions from neutral molecules. Such a process will be accelerated by an increase in the polarity of the medium such as would be produced by an increase in the concentration of nitric acid. In the case of nitration in carbon tetrachloride, where the concentration of nitric acid used was very much smaller than in the other solvents (table 3.1), the zeroth-order rate of nitration depended on the concentrationof nitric acid approximately to the fifth power. It is argued therefore that five molecules of nitric acid are associated with a pre-equilibrium step or are present in the transition state. Since nitric acid is evidently not much associated in carbon tetrachloride a scheme for nitronium ion formation might be as follows ... 

Ion formation region from suitable atmospheric pressure inlet... 

These effects of differential vapor pressures on isotope ratios are important for gases and liquids at near-ambient temperatures. As temperature rises, the differences for volatile materials become less and less. However, diffusion processes are also important, and these increase in importance as temperature rises, particularly in rocks and similar natural materials. Minerals can exchange oxygen with the atmosphere, or rocks can affect each other by diffusion of ions from one type into another and vice versa. Such changes can be used to interpret the temperatures to which rocks have been subjected during or after their formation. 

Field desorption. The formation of ions in the gas phase from a material deposited on a solid surface (known as an emitter) that is placed in a high electrical field. Field desorption is an ambiguous term because it implies that the electric field desorbs a material as an ion from some kind of emitter on which the material is deposited. There is growing evidence that some of the ions formed are due to thermal ionization and some to field ionization of material... 

The chromium can be stabilized in a limited way to prevent surface fixation by addition of formate ions. The formate displaces the sulfate from the complex and masks the hydroxyl ions from forming the larger higher basicity complexes. This stabilization can then be reversed in the neutralization to a pH of about 4.0 and taimage becomes complete. This simple formate addition has decreased the time of chrome tanning by about 50% and has greatly increased the consistent quaHty of the leather produced. 

Deposition of MnO from a solution containing Mn cations on the anode is not considered the primary electrode process. Initially the Mn (ITT) ion is formed on the anode (73). MnO formation arises from Mn(TTT) disproportionation ... 

Because of analogy of radical formation by iron(II) ion from either peroxides or oxaziridines, the latter were proposed repeatedly as initiators of radical chains, e.g. in styrene polymerization and in treatment of unsaturated polyesters. Oxaziridines appear to be easier to prepare than peroxides and to be less hazardous in handling (76MI50801). 

The formation of ethyl cyano(pentafluorophenyl)acetate illustrates the intermolecular nucleophilic displacement of fluoride ion from an aromatic ring by a stabilized carbanion. The reaction proceeds readily as a result of the activation imparted by the electron-withdrawing fluorine atoms. The selective hydrolysis of a cyano ester to a nitrile has been described. (Pentafluorophenyl)acetonitrile has also been prepared by cyanide displacement on (pentafluorophenyl)methyl halides. However, this direct displacement is always aecompanied by an undesirable side reaetion to yield 15-20% of 2,3-bis(pentafluoro-phenyl)propionitrile. 

Another type of interference in ICPMS is suppression of the formation of ions from trace constituents when a large amount of analyte is present. This effect depends on the mass of the analyte The heavier the mass the worse the suppression. This, in addition to orifice blockage from excessive dissolved solids, is usually the limiting factor in the analysis of dissolved materials. 

Addition of hydride ion from the catalyst gives the adsorbed dianion (15). The reaction is completed and product stereochemistry determined by protonation of these species from the solution prior to or concurrent with desorption. With the heteroannular enolate, (13a), both cis and trans adsorption can occur with nearly equal facility. When an angular methyl group is present trans adsorption (14b) predominates. Protonation of the latter species from the solution gives the cis product. Since the heteroannular enolate is formed by the reaction of A" -3-keto steroids with strong base " this mechanism satisfactorily accounts for the almost exclusive formation of the isomer on hydrogenation of these steroids in basic media. The optimum concentration of hydroxide ion in this reaction is about two to three times that of the substrate. 

The formation of a bromohydrin via the addition of hyprobromous acid to olefins complements the above mentioned route. This reagent adds to the double bond in a tm/w-diaxial manner, the addition being initiated by the attack of a positive bromonium ion from the less hindered side. The... 

The dilithium triimidochalcogenites [Ei2 E(N Bu)3 ]2 form dimeric structures in which two pyramidal [E(N Bu)3] dianions are bridged by four lithium cations to form distorted, hexagonal prisms of the type 10.13. A fascinating feature of these cluster systems is the formation of intensely coloured [deep blue (E = S) or green (E = Se)] solutions upon contact with air. The EPR spectra of these solutions (Section 3.4), indicate that one-electron oxidation of 10.13a or 10.13b is accompanied by removal of one Ei" ion from the cluster to give neutral radicals in which the dianion [E(N Bu)3] and the radical monoanion [E(N Bu)3] are bridged by three ions. ... 

Postulate a transition state structure for the formation of the acetylpyridinium ion from pyridine and acetic anhydride. 

The electric field-jump method is applicable to reactions of ions and dipoles. Application of a powerful electric field to a solution will favor the production of ions from a neutral species, and it will orient dipoles with the direction of the applied field. The method has been used to study metal ion complex formation, the binding of ions to macromolecules, and acid-base reactions. 

First, let us consider the formation of ions from covalently bound species, i.e., the heterolytic cleavage of the covalent (or partially covalent) bond. Charge separation under the influence of the solvent generates an ion pair in a process called ionization this ion pair may then separate into free ions in a dissociation step (Eq. 8-18). 

Inspection of the citrate structure shows a total of four chemically equivalent hydrogens, but only one of these—the pro-/J H atom of the pro-i arm of citrate—is abstracted by aeonitase, which is quite stereospecific. Formation of the double bond of aconitate following proton abstraction requires departure of hydroxide ion from the C-3 position. Hydroxide is a relatively poor leaving group, and its departure is facilitated in the aeonitase reaction by coordination with an iron atom in an iron-sulfur cluster. 

Display the lowest-unoccupied molecular orbital (LUMO) for cyclohexyl bromonium ion. From which side will the Br attack Will this lead to formation of cis-1,2-dibromo-cyclohexane or 1,2-dibromocyclohexane Is this... 

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