Hydrogenation of bicarbonate

Heterogeneous Catalyst Hydrogenation of Bicarbonate to Formate in Aqueous Solutions." Journal ofCatalysis, 110, 184-190. 

RuCI2(/ tppms)2 2 was found to be an excellent catalyst (precursor) for the hydrogenation of bicarbonate to formate especially when an excess of mtppms was added. When the reactions were run in the presence of C02, a very high rate increase was observed at /4H2) 60bar,/)(CO2) = 35 bar at 80 C, a0.3MNaHCO3 solution... 

Figure 3.5 Hydrogenation of bicarbonate catalyzed by [RuCI2(PTA)4] as a function of pH. [Ru]=2.61 x 10 3 M, [C02]+ [NaHCO ]=l M, 50 °C, p(H2)=60 bar. Reprinted with permission fromInorg. Chem. 2000,39,5083. Copyright (2000) American Chemical Society.

Table 7.7 Catalyst screening for aqueous hydrogenation of bicarbonate at different pH values and temperatures...

The amount of bicarbonate solution varies, depending on the weight of hydrogen chloride used. There is usually required 250-350 ml. 

Pure tin is completely resistant to distilled water, hot or cold. Local corrosion occurs in salt solutions which do not form insoluble compounds with stannous ions (e.g. chloride, bromide, sulphate, nitrate) but is unlikely in solutions giving stable precipitates (e.g. borate, mono-hydrogen phosphate, bicarbonate, iodide) . In all solutions, oxide film growth occurs and the potential of the metal rises. Any local dissolution may not begin for several days but, once it has begun, it will continue, its presence being manifested... 

In a recent screening of different metal salts, Lane and Burgess found that simple manganese(n) and (in) salts catalyzed the formation of epoxides in DMF or t-BuOH in the presence of aqueous hydrogen peroxide (Scheme 6.7) [68]. It was further established that the addition of bicarbonate was of importance for the epoxidation reaction. 

Along with the respiratory system, the renal system maintains acid-base balance by altering the excretion of hydrogen and bicarbonate ions in the urine. When the extracellular fluid becomes acidic and pH decreases, the... 

Several cases of spontaneous ignition after exposure to air of fine coke particles removed from filter strainers on a petroleum refinery furfural extraction unit have been noted. This has been associated with the use of sodium hydrogen carbonate (bicarbonate) injected into the plant for pH control, which produced a pH of 10.5 locally. This would tend to resinify the aldehyde, but there is also the possibility of a Cannizzaro reaction causing conversion of the aldehyde to furfuryl alcohol and furoic acid. The latter, together with other acidic products of autoxidation of the aldehyde, would tend to resinily the furfuryl alcohol. Pyrolysis GLC showed the presence of a significant proportion of furfuryl alcohol-derived resins in the coke. The latter is now discarded into drums of water, immediately after discharge from the strainers, to prevent further incidents. 

Figure 5 displays a typical time dependent trace of the hydrogen production during catalysis of the WGSR by Cr(CO)e. The decrease in activity of mature catalyst solutions is due to the consumption of KOH by C02, i.e., the formation of bicarbonate (C02 + 0H" HC03"). Reaction solutions prepared from Cr(CO)e with KHC03 as the added alkaline were much less active than their KOH counterparts. Experiments are planned at higher reaction temperatures in an effort to minimize this behavior. However, at 100° the Cr(C0) catalyst is quite active for the decomposition of formate ion to H2 plus C02 (vide infra). 

Hydrogenation of C02 to formic acid (Eq. (1)) is thermodynamically unfavorable unless a base is present (see Scheme 17.1) the proton transfer to the base drives the reaction. In the absence of a base, the reaction usually fails completely or provides only small yields [19, 20], even though the initial rate of reaction was high in one case [21]. For the reaction in water, NaOH, bicarbonates, carbonates and even dialkylamines [22] are used as the base. For the reaction in or-... 

In basic aqueous solutions, C02 exists primarily in the bicarbonate or carbonate forms. Thus, the hydrogenation of either C02 or bicarbonate salts in such solutions could conceivably proceed by hydrogenation of the bicarbonate anion. Pd... 

The water soluble tertiary phosphine complex of ruthenium(II), [RuCl2(PTA)4], (PTA=l,3,5-triaza-7-phosphaadamantane) was used as catalyst precursor for the hydrogenation of CO2 and bicarbonate in aqueous solution [51]. For this relatively... 

Acetazolamide is an aromatic sulfonamide used as a carbonic anhydrase inhibitor. It facilitates production of alkahne urine with an elevated biocarbonate, sodium, and potassium ion concentrations. By inhibiting carbonic anhydrase, the drug suppresses reabsorption of sodium ions in exchange for hydrogen ions, increases reflux of bicarbonate and sodium ions and reduces reflux of chloride ions. During this process, chloride ions are kept in the kidneys to cover of insufficiency of bicarbonate ions, and for keeping an ion balance. Electrolytic contents of fluid secreted by the kidneys in patients taking carbonic anhydrase inhibitors are characterized by elevated levels of sodium, potassium, and bicarbonate ions and a moderate increase in water level. Urine becomes basic, and the concentration of bicarbonate in the plasma is reduced. 

Mechanism of Action A carbonic anhydrase inhibitor that reduces formation of hydrogen and bicarbonate ions from carbon dioxide and water by inhibiting, in proximal renal tubule, the enzyme carbonic anhydrase, thereby promoting renal excretion of sodium, potassium, bicarbonate, and water. Ocular Reduces rate of aqueous humor formation, lowers intraocular pressure. Therapeutic Effect Produces anticonvulsant activity. 

The second method, illustrated in Section B for the ammonium salt, relies on the direct stoichiometric acid-base reaction between V2Os and the oxide, hydroxide, carbonate, or hydrogen carbonate (bicarbonate) of the desired positive ion. Surprisingly, this method works well for quite a variety of ions, even in cases where both reactants are only slightly soluble in water (e.g., CaO + V2Os). 

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