The reaction of sodium arsenite with sodium chlorite

Existing procedures for the standardisation of sodium chlorite solutions are critically examined and a suitable method detailed. The reaction between sodium chlorite and sodium arsenite solutions is discussed; reaction is quantitative in the presence of sodium bicarbonate and osmic acid as catalyst.     

XPS characterization of sodium percarbonate granulated with sodium silicate

Granular sodium percarbonate has been characterized by X-ray powder diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The O1s binding energy for the solvating hydrogen peroxide molecules is 535.8 eV. Sodium percarbonate is stabilized by sodium silicate and polyphosphate.     

Preparation of alkaline earth phosphates with sol containing sodium alginate and sodium diphosphate

Magnesium hydrogen phosphate, calcium hydroxyapatite, and strontium hydroxyapatite were successfully prepared from sol consisting of sodium alginate and Na4P2O7 with Mg2+, Ca2+, and Sr2+ in the corresponding nitrates, respectively. It is revealed that the order of the addition of those substrates and the role of sodium alginate are important factors for the preparation of desired phosphate compounds. According to the previous paper on the preparation of calcium hydroxyapatite, sodium alginate was mixed with aqueous Na4P2O7, followed by the addition of the aqueous divalent cations, resulting in the poor formation of the target phosphates. However, as a revised sol-gel technique, sodium alginate was added to the mixture of Na4P2O7 and aqueous Mg2+ and Sr2+, resulting in a rather favorable formation of MgHPO4 and strontium hydroxyapatite, respectively, while the sol thus obtained was stable within a few days. However for aqueous Ca2+, calcium hydroxyapatite could not be obtained through the revised sol-gel technique. In the preparation of magnesium hydrogen phosphate, sodium alginate contributes mainly to the sol formation of the precursor. The ion exchange between Na+ in sodium alginate and aqueous Ca2+ was important for the preparation of calcium hydroxyapatite. In contrast, the reaction of sodium alginate with the mixture of Na4P2O7 and aqueous Sr2+ afforded strontium hydroxyapatite at the specific ratio of those three substrates. The structure of calcium and strontium phosphates prepared from the revised sol-gel process evidently depended on the amount of sodium alginate introduced into the mixture of Na4P2O7 and the corresponding divalent cations.     

Sedimentation of kaolin suspension with copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate

The sedimentation kinetics of kaolin suspension under the action of copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate was studied. The infl uence exerted on the process by the concentration, molecular weight, chemical composition, and conformational state of copolymer macromolecules in solution, and also by the concentration and particle size of the dispersed phase and by salt additives (NaCl, CaCl₂) was examined.     

2,4,6-Trichloropyrimidine. Reaction with sodium amide

The first reaction between 2,4,6-trichloropyrimidine 1 and anionic nitrogen nucleophiles is described. Treatment of 1 with one equivalent of sodium amide gave mixtures of 4-amino-2,6-dichloropyrimidine 2 and 2-amino-4,6-dichloropyrimidine 3 . Additional quantities of sodium amide failed to provide either diamino- or triaminopyrimidines. Instead, the strongly basic nature of sodium amide led to higher molecular products that were not characterized.     

丙二酰氧基硼氢化钠与烯烃的选择性硼氢化

叙述了丙二酰氧基硼氢化钠的制备及其原位与烯烃的选择性硼氢化反应。通过化学反应证实,丙二酰氧基硼氢化钠在THF中与脂肪族末端烯烃例如1-庚烯的硼氢化反应,有98%的硼原子加到双键末端碳原子上,只有2%的硼原子加到2-位上,生成单取代的有机硼化合物,即丙二酰氧基硼氢化钠是一个单官能硼氢化试剂。     

Concentration effect in copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in aqueous solutions

The effect of the concentration of the initial monomer mixture, the comonomer ratio, and temperature on the kinetic parameters of the process and the characteristics of the resulting copolymers in the homogeneous copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in aqueous solutions at 50–80°C in the presence of potassium persulfate is studied. The initial rate of copolymerization and the molecular mass of copolymers increase with the total initial concentration of the monomer mixture and the content of sodium 2-acrylamido-2-methylpropanesulfonate. As temperature increases, the initial rate of copolymerization increases and the molecular mass of the copolymer diminishes. When copolymerization is performed in 10, 30, and 40% aqueous solutions of the monomers, the resulting copolymers are enriched in sodium acrylate units. The content of sodium 2-acrylamido-2-methylpropane-sulfonate units in the copolymer slightly increases with an increase in the total initial concentration of the monomer mixture.     

Indirect determination of ampicillin sodium with sodium nitrate-ammonium thiocyanate-water system by extraction-flotation of cuprous thiocyanate

A novel method for indirect determination of ampicillin sodium by the extraction-flotation is proposed in this paper. It is indicated that the degradation of ampicillin sodium took place in the presence of 0.30 M sodium hydroxide in boiling water for 20 min. At pH 4.0, in the presence of ammonium thiocyanate, the thiol group of the degradation product of ampicillin sodium could reduce copper(II) to copper(I) due to the formation of the emulsion cuprous thiocyanate precipitation. By determining the residual amount of copper(II) in the solution and calculating the flotation yield of cuprous thiocyanate, the indirect determination of ampicillin sodium can be performed. When the concentration of cooper(II) was 5.0 μg/mL, a good linear relationship was obtained between the flotation yield of cuprous thiocyanate and the amount of ampicillin sodium in the range of 0.40～9.6 μg/mL. The linear equation is E = 4.1469 + 3.7949c with the correlation coefficient r = 0.9992, and the detection limit (3σ/K) of 0.37 μg/mL. Each parameter has been optimized and the reaction mechanism has been studied. The method has been successfully applied to the determination of ampicillin sodium in pharmaceutical, human plasma and urine samples. Analytical results obtained are satisfactory.     

Copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in water-dimethyl sulfoxide solutions

The solvent effect on the kinetic features of the synthesis and molecular characteristics of the copolymers in homogeneous radical copolymerization of sodium 2-acrylamido-2-methylpropanesulfonate with sodium acrylate in water and water-dimethyl sulfoxide mixtures (75: 25, 50: 50, 25: 75) at pH 9 and 60°C in the presence of potassium persulfate was studied     

Interaction of 5-fluorouracil with sodium carboxymethylcellulose

The interaction of an anticancer drug, 5-fluorouracil with sodium carboxymethylcellulose in aqueous solution was studied with a spectral method and viscosity measurement. From the binding data, the standard molar change in enthalpy, entropy and the number of binding sites on polymer were calculated. The standard molar change of enthalpy of 5-fluorouracil is about — 7 Kcal/mol with sodium carboxymethylcellulose. The enthalpy change is a considerably greater.     

Interaction of sodium benzoate with trypsin by spectroscopic techniques

The toxicity of sodium benzoate to trypsin was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, UV-visible absorption spectroscopy and circular dichroism (CD) spectroscopy under mimic physiological conditions. Sodium benzoate could unfold trypsin by decreasing the β-sheet structure, which leads to more exposure of internal amino acid groups and the obvious intrinsic fluorescence quenching with the rising concentration of sodium benzoate. The results of spectroscopic measurements indicated that sodium benzoate changed the internal microenvironment of trypsin and induced the alteration of the whole molecule, which were performed toxic effects on the organism. Trypsin and sodium benzoate interacted with each other to produce a substance by van der Waals forces and hydrogen bond, the model of which was shown by AutoDock software.     

Nitroarene catalyzed oxidation with sodium percarbonate or sodium perborate as the terminal oxidant

A new catalytic oxidation method for the preparation of aromatic carboxylic acids from methyl aryl ketones is reported. The method is an alternative to the haloform reaction; it is benign and affords the desired product without production of any harmful side products. The catalytic cycle is based on the use of an electron-deficient nitroarene as catalyst with either of the two cheap and green oxidants sodium percarbonate or sodium perborate. The method gives a good yield (87%) and shows excellent selectivity when the model substrate (acetophenone) is oxidized. A series of benzoic acids of industrial interest were prepared by means of this method.     

Potentiometric method of determination of sodium ions with the help of the glass electrode with sodium function

Summary The possibility of determination of the concentration of ions in natural waters with the help of the glass electrode with sodium function was demonstrated.     

Effect of sodium salicylate, sodium oxalate, and sodium chloride on the micellization and adsorption of sodium deoxycholate in aqueous solutions

The salicylate ion increases the rate of bile flow (choleretic effect) and bile salts are known to affect the colonic absorption of oxalate. Owing to this physiological relevance of salicylate and oxalate ions, critical micelle concentration (cmc) values of sodium deoxycholate (NaDC) were determined in aqueous sodium oxalate, sodium salicylate, and sodium chloride solutions by using surface tension, fluorescence, and EMF methods. The results indicate, besides a counterion effect, the influence of coanions on the cmc. In the range from 25 to 40 °C, cmc increases almost linearly with temperature. In the temperature range from 30 to 40 °C, the counterion binding constant β of NaDC micelles has the same value (0.17±0.01) in the presence of sodium chloride and sodium salicylate. On the other hand, in sodium oxalate solution β=0.05±0.02 when oxalate concentration is less than or equal to c* and β=0.48±0.04 above c*, where c*≈0.038 mol kg(-1). EMF measurements also supported this type of counterion binding to NaDC micelles in sodium oxalate solutions. In sodium oxalate solution, at c* a change in the shape of deoxycholate micelles is expected to take place. Salicylate, oxalate, and chloride coanions have a similar effect on the adsorption of NaDC. This study reveals that the choleretic effect of salicylate is not due to the influence of salicylate ions on the micellization of NaDC.     

Reduction of 2,3,4-substituted quinolines with sodium borohydride

1,2-Dihydroquinolines were obtained by the reduction of 3-substituted 2-methyl-4-phenylquinolines with sodium borohydride in aliphatic carboxylic acids; N-alkyl derivatives are also formed. The corresponding 1,4-dihydroquinoline was obtained in the reaction of 2-methyl-3-nitroquinolinium perchlorate with sodium borohydride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1680–1686, December, 1991.     

二氧化碳和水气氛对高钠煤转化过程中钠迁移的影响

对新疆的两种高钠煤（伊犁煤YL、呼图壁煤HTB）进行了N₂、CO₂和H₂O气氛和不同温度下钠迁移的研究。采用逐级萃取和湿法消解法确定了原煤、半焦中钠的赋存形态,定量研究了两种煤中钠的挥发及迁移规律。结果表明,YL煤的形态钠中水溶钠占80.08%,HTB煤的形态钠中不溶钠占61.54%。不同气氛下,升高温度都可促进两种煤中钠的挥发,半焦中水溶钠比例减小,醋酸铵可溶钠比例会出现先增加后减少现象,盐酸可溶钠比例呈增加趋势。对于YL煤,CO₂气氛可抑制钠的挥发,H₂O蒸气可促进钠的挥发;900℃时,YL煤CO₂气氛下钠挥发仅为N₂气氛下的50.25%,而H₂O气氛钠挥发为N₂气氛下的111.45%。对于HTB煤,CO₂气氛也可抑制钠的挥发,900℃时CO₂气氛下钠挥发为N₂气氛的80.91%;HTB煤在H₂O蒸气下,800℃之前钠挥发高于N₂,当900℃时,钠挥发略低于N₂气氛。YL煤形态钠中以水溶钠为主,其挥发的同时会向盐酸可溶钠及不溶钠转变。而HTB煤形态钠中以不溶钠为主,其次是水溶钠,CO₂和H₂O气氛能促进不溶钠向其他可溶态钠转变。     

An unusual reaction of cyclopropenylphosphonium bromide with sodium polyphosphides – A novel approach to sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide

1,2,3-Triphenylcyclopropenylphosphonium bromide reacts with sodium polyphosphides to give sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide in high yield.     

Interaction of polypeptide neurotoxins with a receptor site associated with voltage-sensitive sodium channels

Anthopleurin A, a polypeptide toxin from the Pacific sea anemone Anthopleura xanthogrammica, enhances persistent activation of voltage-sensitive sodium channels by the alkaloid toxins veratridine and batrachotoxin with K0.5 = 20 nM. This effect is inhibited by depolarization. There is a close correlation between enhancement of sodium channel activation and block of [125I]scorpion toxin binding by unlabeled scorpion toxin, sea anemone toxin II from Anemonia sulcata, and Anthopleurin A, indicating that these three polypeptide toxins interact with a common receptor site in modifying sodium channel function. Photo-activable derivatives of scorpion toxin label a single Mr approximately 250,000 polypeptide chain at the polypeptide toxin receptor site. Labeling is blocked by unlabeled scorpion toxin or depolarization and is not observed in variant neuroblastoma clones, which lack sodium channels. These results identify a protein component of the polypeptide toxin receptor site of voltage-sensitive sodium channels.     

Reaction of sodium amide with 1-chloromethylsilatrane

The reaction of 1-chloromethylsilatrane with sodium amide in benzene is accompanied by ring expansion with formation of 1-amino-2-carba-3-oxahomosilatrane.     

Ruthenium-catalyzed oxidation of alcohols with sodium bromate

Ruthenium trichloride-catalyzed oxidation of secondary alcohols with sodium bromate under basic conditions affords ketones in the excellent yields.