Potassium Hydrogen Carbonate Research Articles

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Degradation of coals and chars from poly(vinyl chloride) (PVC) and mixtures of PVC with other polymers such as polyethylene glycol, poly(vinyl alcohol), polystyrene, and polyethylene using a mixture of copper(II) oxide (CuO) and aqueous potassium carbonate solution at 500 °C to give a mixture of aliphatic and aromatic hydrocarbons, carbon dioxide, potassium hydrogencarbonate, and water soluble and easily decomposable materials with dilute hydrochloric acid. It was revealed that CuO promoted the decomposition of highly aromatized materials such as chars from PVC or coals and the preferential formation of benzene in the decomposition of those materials.

Inhibition of azoxymethane-induced rat colon carcinogenesis by potassium hydrogen D-glucarate.

While calcium D-glucarate was shown to inhibit chemical carcinogenesis in various animal models, the effect of potassium hydrogen D-glucarate has not been extensively investigated. In the present study, potassium hydrogen D-glucarate markedly inhibited azoxymethane (AOM)-induced colon carcinogenesis in male F344 rats. Potassium hydrogen D-glucarate (PHG) or potassium hydrogen carbonate (PHC) were administered to rats in a diet (140 mmol/kg). Continual post-initiation treatment with potassium hydrogen D-glucarate reduced both tumor incidence and multiplicity at sacrifice by ca. 60%, while PHC had no effect. amelioration of overexpression of the betaG gene in rat colon carcinomas was observed using RT-PCR and Northern blot analysis. We hypothesize that previously demonstrated conversion of PHG to D-glucaro-1,4-lactone, a potent inhibitor of beta-glucuronidase (betaG), may be responsible for this effect. The mechanism of PHG inhibition of colon carcinogenesis may also involve suppression of cell proliferation and possibly alterations in cholesterol synthesis or cholesterol metabolism to bile acids. In conclusion, PHG possesses excellent potential as a natural, apparently non-toxic inhibitor to prevent colon cancer.

Determination of Phenytoin and Its Major Metabolites in Human Serum by High-Performance Liquid Chromatography with Fluorescence Detection

A highly sensitive fluorometric high-performance liquid chromatographic method was developed for the simultaneous determination of phenytoin and its major metabolites [5-(3-hydroxyphenyl)-5-phenylhydantoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin]. After extracting these compounds and 5-(4-methylphenyl)-5-phenylhydantoin (MPPH) as an internal standard from serum (50 μl) with ethyl acetate, they were further converted into the corresponding fluorescent derivatives by a reaction with 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone in the presence of potassium hydrogen carbonate and dibenzo-18-crown-6 in acetonitrile. The derivatives were separated by reversed-phase chromatography on a YMC-Pack ODS-A column with a mixture of acetonitrile?50 mM phosphate buffer (pH 7.0) (4:6, v/v) as a mobile phase, and were then detected spectrofluorometrically at 448 nm with excitation at 365 nm. The detection limits for phenytoin, 5-(3-hydroxyphenyl)-5-phenylhydantoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin added to serum were 0.6, 3.0 and 0.8 ng (2.4, 11 and 3.1 pmol) ml-1 serum at a signal-to-noise ratio of three. The method was applied to determine the unbound- and total-phenytoin and the metabolites levels in the serum obtained from two healthy volunteers, after oral administration of the drug.

Incoherent elastic-neutron-scattering study of the vibrational dynamics and spin-related symmetry of protons in theKHCO3crystal

The potassium hydrogen carbonate crystal $({\mathrm{KHCO}}_{3})$ and its deuterated analog $({\mathrm{KDCO}}_{3})$ contain centrosymmetric dimer entities $({\mathrm{HCO}}_{3}^{\mathrm{\ensuremath{-}}}{)}_{2},$ or $({\mathrm{DCO}}_{3}^{\mathrm{\ensuremath{-}}}{)}_{2},$ linked by moderately strong hydrogen or deuterium bonds. The OH/OD bonds are virtually parallel to each other throughout the crystal. The incoherent elastic-neutron-scattering functions (IENSF) ${S(Q}_{x}{,Q}_{y}{,Q}_{z}=0,\ensuremath{\omega}=0)$ and ${S(Q}_{x}{,Q}_{y}=0,{Q}_{z},\ensuremath{\omega}=0)$ were measured over the momentum transfer range from \ensuremath{\sim}0 to \ensuremath{\sim}30 ${\mathrm{\AA{}}}^{\mathrm{\ensuremath{-}}1}$, with resolution of $\ensuremath{\Delta}|\mathbf{Q}|\ensuremath{\sim}1{\AA{}}^{\ensuremath{-}1}.$ The components of the momentum transfer ${Q}_{x},$ ${Q}_{y},$ and ${Q}_{z}$ were parallel to the mean directions of the stretching, in-plane, and out-of-plane bending modes of protons or deuterons, respectively. For ${\mathrm{KHCO}}_{3},$ the broad incoherent scattering peaks, centered at $\mathbf{Q}=0,$ are not amenable to the IENSF calculated with various models: the single harmonic oscillator, the double minimum potential, and the pair of coupled harmonic oscillators. Then, the degenerate ground state of a pair of coupled protons is regarded as composed of indistinguishable fermions. According to the Pauli principle, the symmetric and antisymmetric coordinates are singlet and triplet states, respectively. The IENSF gives quantum interferences that compare favorably to the observations. The estimated mean-square amplitudes in the ground state are amenable to isolated harmonic proton oscillators. Incoherent scattering for ${\mathrm{KDCO}}_{3}$ is amenable to Gaussian profiles for bosons. There is no evidence for quantum interference. The profile narrowing reveals an increase of the mean-square amplitudes attributed to a rather large coupling of the deuteron dynamics to the crystal lattice.

The Pauli principle and the vibrational dynamics of protons in solids: A new spin-related symmetry

Inelastic neutron scattering studies of some hydrogen bonded crystals (e.g., potassium hydrogen carbonate, KHCO 3) have revealed that the dynamics of protons is largely decoupled from the lattice. The KHCO 3 crystal is a prototypical system for proton dynamics which contains centro-symmetric dimer entities (HCO 3 −) 2 linked by moderately strong hydrogen bonds. The quantum dynamics of pairs of coupled oscillators is analyzed. It is shown that the Pauli principle applied to normal coordinates for fermions gives new quantum properties in the degenerate ground state. Vibrational wave functions for the singlet and triplet states are derived. A new spin-related selection rule in proposed: the dynamics of fermions (e.g., H atoms) is decoupled from the dynamics of bosons (e.g., C and O atoms). Scattering functions for the protons are calculated with various models: the single harmonic oscillator, the double minimum potential and pairs of coupled harmonic oscillators. It is concluded that quantum interferences should be observed with elastic neutron scattering for pairs of coupled fermions.

A new view of the quantum dynamics for proton transfer along hydrogen bonds: Vibrational spectroscopy with neutrons

AbstractInelastic neutron scattering is an ideal tool to observe proton transfer dynamics along hydrogen bonds in the quantum regime. “Tunnelling” transitions associated with the quantum transfer of a single proton have been observed for potassium hydrogen carbonate, KHCO3, and similar hydrogen bonded complexes in the solid state. More recently, the tunnelling transition was observed for a polypeptide: polyglycine II. The “tunnelling” bands are rather sharp. Therefore, the proton transfer is largely decoupled from the heavy atom dynamics. Force‐field calculations including INS intensities confirm that the proton dynamics are almost totally decoupled from those of the surrounding heavy atoms. This is in contrast to the “vibration assisted tunnelling” model that supposes a large modulation of the double minimum potential by the low frequency modes of the hydrogen bond. The double minimum potential functions governing the proton transfer are discussed.

Efficient Recovery of Carbon Dioxide from Flue Gases of Coal-Fired Power Plants by Cyclic Fixed-Bed Operations over K2CO3-on-Carbon

An efficient chemical absorption method capable of cyclic fixed-bed operations under moist conditions for the recovery of carbon dioxide from flue gases has been proposed employing K2CO3-on-carbon. Carbon dioxide was chemically absorbed by the reaction K2CO3 + CO2 + H2O ⇄ 2KHCO3 to form potassium hydrogencarbonate. Moisture, usually contained as high as 8−17% in flue gases, badly affects the capacity of conventional adsorbents such as zeolites, but the present technology has no concern with moisture; water is rather necessary in principle as shown in the equation above. Deliquescent potassium carbonate should be supported on an appropriate porous material to adapt for fixed-bed operations. After breakthrough of carbon dioxide, the entrapped carbon dioxide was released by the decomposition of hydrogencarbonate to shift the reaction in Eq.1 in reverse on flushing with steam, which could be condensed by cooling to afford carbon dioxide in high purity. Among various preparations of alkaline-earth carbonates (...

Synthesis of (15 E)-17β-hydroxyandrost-4-ene-3,15-dione 15-( O-carboxymethyl)oxime, a potential hapten for testosterone immunoassays

The key intermediate, 15-oxandrost-5-ene-3β, 17β-diyl 3-acetate 17-benzoate ( 10), was prepared by a five-step procedure based on the addition of 4-methoxybenzyl alcohol to 3β-hydroxyandrosta-5,15-dien-17-one ( 1). The resulting C-15 isomers were separated as acetates. In both series, the 17-ketones were reduced to 17β-hydroxy derivatives, and after benzoylation, the protecting methoxyphenylmethyl group at position 15 was removed with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, leaving 15β-hydroxyandrost-5-ene-3β, 17β-diyl 3-acetate 17-benzoate ( 6) and its 15α-isomer 9. After Jones oxidation, both benzoates afforded the identical ketone 10. The reaction of 10 with ( O-carboxymethyl)hydroxylamine in pyridine followed by diazomethane esterification gave (15 E)-15-oxandrost-5-ene-3β, 17β-diyl 3-acetate 17-benzoate 15-( O-carboxymethyl)oxime methyl ester ( 11). Methyl ester 11 was successively submitted to acidic deacetylation, Oppenauer oxidation, potassium hydroxide treatment, and reesterification with diazomethane to give (15 E)-17β-hydroxyandrost-4-ene-3,15-dione 15-( O-carboxymethyl)oxime methyl ester ( 14). After purification, ester 14 was hydrolyzed with potassium hydrogen carbonate in aqueous methanol at elevated temperature into free testosterone 15-( O-carboxymethyl)oxime ( 15).

Generation and trapping of monomeric metaphosphoric acid esters in solution: Mechanistic investigation into the fragmentation of mixed carbonic-phosphoric acid anhydrides and the chelotropic breakdown of cyclic pyrocarbonate esters

The generation of alkyl-substituted monomeric metaphosphoric acid esters (ROPO2) 4 in solution is described, utilizing two different methods based on the condensation of alkyl phosphorodichloridates either with anhydrous potassium hydrogen carbonate or with the novel disodium pyrocarbonate salt 5, which is formed in quantitative yield from diethyl pyrocarbonate by treatment with two equivalents of sodium trimethylsilanolate in THF at 0°C. The first method is believed to proceed via a transient mixed carbonic-phosphoric anhydride 3, which decomposes at room temperature with release of 1 mol each of hydrogen chloride and carbon dioxide to produce 4. In the other method, 31P NMR spectroscopy indicated the involvement of a cyclic pyrocarbonate phosphate (2-alkoxy-1,3,5-trioxaphosphorinane-4,6-dione-2-oxide) 6, which decomposed in situ with the release of 2 mol of carbon dioxide. In both cases, the metaphosphate thus formed spontaneously self-condensed to produce polymeric species with P-O-P bonds having characteristic 31P NMR signals clustered in the δ -12 and -24 regions. When metaphosphate 4 is generated by either process in the presence of styrene oxide, polymerization is avoided, and trapping occurs with the exclusive formation of a diastereomeric mixture of 2-alkoxy-1,3,2-dioxaphospholane-2-oxides 7 (cis, trans). In order to shed some mechanistic light on the formation of 7, 31P NMR studies have been carried out on the individual trapping reactions between (—)-methyl metaphosphate 4d and racemic styrene oxide, as well as its optically pure forms. Based on evidence that these transformations proceed by inversion of configuration at the phenyl-bearing carbon of styrene oxide, a mechanism is invoked whereby the dipolar metaphosphate 4d reacts both as an electrophile and as a nucleophile in a self-catalyzed process via the activated complex 9d. © 1996 John Wiley & Sons, Inc.

The Sol Concentration Effect in n-Butylammonium Vermiculite Swelling

AbstractThe swelling of n-butylammonium vermiculite in water was investigated as a function of the sol concentration (r), the salt concentration (c) and the temperature (T).The interlayer spacing in the gel phase was investigated as a function of r and c by neutron diffraction and by laboratory experiments which measured how many times its own volume a crystal would absorb. The salt concentration was found to be the stronger variable with the interlayer spacing decreasing proportional to c0.5, which is consistent with previous results and with the Coulombic attraction theory. The sol concentration was found to affect the swelling for two reasons, the salt fractionation effect and the trapped salt effect. Both of these cause the salt concentration in the supernatant fluid to be greater than that originally added to the crystals and so reduce the swelling.A new method was used for extracting the solution from inside the gels by collapsing the gels by the addition of potassium hydrogen carbonate. The Volhardt titration was carried out on the extracted and supernatant solutions from about 250 gels. The ratio of the external to the internal chloride concentration was found to be approximately constant across the range of salt concentrations. Its average value was equal to 2.6, again in agreement with Coulombic attraction theory and showing the surface potential to be constant at about 70 mV.The (r, c, T) boundary of the two phase colloid region was investigated by three methods. A plot of log c against Tc was linear within experimental accuracy, with a gradient of 0.077 K−1 or 13 K per log unit. This shows that the surface potential varies by only 1 mV per decade in the salt concentration. The system is therefore governed by the Dirichlet boundary condition and not by the Nernst equation.

Electrical conductivity and relative permittivity of KHCO3

The electrical conductivity σ and the relative permittivity (κ) as function of temperature 300 K < T < 400 K are measured and presented for potassium hydrogen carbonate KHCO3. It seems likely that the compound undergoes tow structural phase transitions at ≈ 318 and ≈ 365 K. The differential thermal analysis DTA and the thermogravimetric analysis TGA are performed in the same temperature range. The thermogram confirms the existence of structural phase transitions, whereas TGA indicates the absence of any loss in weight. The data are correlated to the crystal structure and the arrangement of the molecules in the crystal including the hydrogen bonding dimers (HCO3).

Freezing-temperature depressions of aqueous potassium hydrogen carbonate

Osmotic and activity coefficient of aqueous potassium hydrogen carbonate at freezing temperatures determined from cryoscopic measurements are reported.

From Gas Phase to Condensed Phase: Towards Metaphosphate Generation in Solution

Abstract Based on attempts to generate methyl metaphophate in solution by thermal fragmentation of a cyclic pyrocarbonate phosphate, it has emerged that reaction of methyl dichlorophosphate with anhydrous potassium hydrogen carbonate serves as an alternative approach as proven by trapping with styrene oxide to form a 1,3,2-dioxaphospholane.

Potassium promotion of iron oxide dehydrogenation catalysts supported on magnesium oxide: 1. Preparation and characterization

Catalysts of iron oxide supported on magnesium oxide and promoted with potassium were prepared by incipient wetness impregnation of preshaped magnesium oxide support pellets with a solution of an iron complex, either ammonium iron(III) citrate or ammonium iron(III) EDTA and potassium carbonate. Iron and potassium were applied either simultaneously or consecutively. As determined using X-ray diffraction, thermogravimetric analysis, and magnetic measurements, calcination above 923 K results in the formation of a mixed oxide of iron and potassium, viz., KFeO 2 After calcination at 973 K the average crystallite size of the KFeO 2 phase is about 300 Å. The formation of KFeO 2 appeared to have a strong retarding effect on the reduction of the iron oxide phase to metallic iron. It was found that the KFeO 2 phase is unstable in atmospheric air due to reaction with carbon dioxide and moisture to form potassium (hydrogen)carbonate and (hydrated) iron oxide.

Synthesis of Lantern-type Dinuclear Mixed-Metal Complex of Platinum(II) and Nickel(II)

Abstract Reaction of tetra(4-methylpyridine-2-thiol)platinum(II) chloride (1) with nickel acetate in naphthalene at 120 °C in the presence of potassium hydrogen carbonate affords acetonitriletetra(μ-4-methylpyridine-2-thiolato)platinum(II)nickel(II) (2). Structural characterization has been made for 1 and 2, and confirmed that 2 has a lantern type structure.

Über die radikalische Desoxygenierung sekundärer Alkohole

On the Radical Deoxygenation of Secondary AlcoholsThe derivatives 1c–1f were prepared from tetramethyl‐(+)‐catechin (1b). Their radical reduction with tri‐n‐butyltin hydride or tris(trimethylsilyl)silane in the presence of azobis‐(isobutyronitrile) as initiator led to (2R)‐(—)‐3′,4′,5,7‐tetramethoxyflavan (1g). The best yield of 1g (about 75% from 1b) was achieved via the N‐(imidazolyl)thiocarbonyl derivative 1c. Analogously the enantiomeric (2S)‐(+)‐3′,4′,5,7‐tetramethoxyflavan (2g) was obtained from tetramethyl‐(+)‐epicatechin (2b) via 2c. Experimental evidence is given which shows that in aqueous solution, with a catalytic amount of potassium hydrogen carbonate, (+)‐catechin (1a) epimerises at the C‐2 position of the flavan skeleton to give (+)‐epicatechin (2a).

Fixation of Carbon Dioxide with Diphenylcarbodiimide as a Model of Biotin Enzyme Active Site and a Weak Base: The Carboxylation of Fluorene under Mild Conditions

Abstract Carbon dioxide was directly fixed into fluorene in the presence of diphenylcarbodiimide (DPC) as a model of a biotin enzyme active site and potassium hydrogencarbonate. It was considered that not only carbon dioxide but also the hydrogencarbonate ion were the carbon source in the presence of DPC. Weak bases such as potassium acetate, potassium propionate, and potassium formate were also effective for carboxylation.

The anisotropy of the proton momentum distribution in KHCO3: A deep inelastic neutron scattering study

We report the anisotropy of the proton momentum distribution in potassium hydrogen carbonate, KHCO3. Using the deep inelastic neutron scattering technique, the mean proton momenta along, and across, the O–H–O bond have been determined. While the momentum across the bond corresponds to a proton in a harmonic potential, that along the bond shows this potential is consistent with a previously proposed double well shape.

N-(bromoacetyl)-N′-[5-(dimethylamino)naphthalene-1-sulphonyl]piperazine as a sensitive labelling reagent for the determination of carboxylic acids by liquid chromatography with peroxyoxalate chemiluminescence and fluorescence detection

The synthesis and application of a labelling reagent for the column liquid chromatographic determination of carboxylic acids using chemiluminescence (CL) detection is described. Dansyl chloride is first reacted with an excess of piperazine and then with bromoacetic acid. The resulting label, N-(bromoacetyl)-N′-[5-(dimethylamino)naphthalene-1-sulphonyl]piperazine (dansyl-BAP), which contains a reactive bromoacetamide group, is stable for at least 6 months. Pre-column derivatization is carried out in polar aprotic media in 30 min at room temperature for aliphatic acids, and in 30 min at 55 °C for aromatic acids, in the presence of 18-crown-6 and potassium hydrogen carbonate as a base catalyst. After derivatization, excess of dansyl-BAP is converted into a relatively polar product by reaction with thymine and is subsequently separated from the derivatized analytes on a silica cartridge. High-performance liquid chromatography is performed on C18 and C8 columns with acetonitrile–water mixtures as the eluent. Fluorescence detection is carried out at an excitation wavelength of 255 nm using a 470 nm emission cut-off filter. Chemiluminescence detection is carried out by adding bis(2-nitrophenyl) oxalate and hydrogen peroxide dissolved in acetonitrile to the column effluent. The fluorescence detection limit is 0.8–1 pmol for acids such as substituted benzoic acids and the drugs naproxen and ibuprofen; the CL detection limit is 25 fmol for retinoic acid, a vitamin A precursor.

Electrochemical Reduction of Carbon Dioxide at Various Metal Electrodes in Aqueous Potassium Hydrogen Carbonate Solution

Abstract The electrochemical reduction of carbon dioxide at various metallic electrodes was carried out potentiostatically at 298 K in aqueous potassium hydrogen carbonate solution in order to make clear the electrocatalysis of metals in reduction of CO2. It was found that metals used as electrodes are classified into four groups according to their main products from CO2, i. e., metallic In, Sn, Hg, and Pb are selective for the production of formic acid; metallic Ag and Au are selective for the formation of carbon monoxide; metallic copper has the highest electrocatalytic activities in formation of hydrocarbons, aldehydes, and alcohols; and metallic Al, Ga, Group a, and Group VIII elements except Pd have scarce electrocatalytic activity in reduction of CO2. Effects of the reduction potential on products from CO2 were also examined in detail for Zn, In, and Au electrodes which have some interesting properties.