Excess Of Sodium Hydroxide Research Articles

The use of hydrochloric acid to improve the germination of sugar-beet seed

This study confirmed that steeping sugar-beet seed in 0.3 M hydrochloric acid for 2 h as the first part of a 12 h treatment, substantially improved performance under cold, wet conditions. Smaller benefits were also found in warmer, drier tests; no detrimental effects were found. Adding excess sodium hydroxide at the end of the acid steep further improved the growth of the inherently slower part of the population under cold, wet conditions. Steeping seed in acid or acid followed by alkali also controlled Phoma betae as effectively as the current commercial thiram step treatment.

Linear polyesters. Products of interfacial polycondensation of bis(4‐hydroxyphenyl) ether with isomeric phthaloyl chlorides

AbstractNew polyesters were obtained by interfacial polycondensation of bis(4‐hydroxyphenyl) ether with phthaloyl, isophthaloyl, and terephthaloyl chlorides. The initial reaction conditions were as follows: the aqueous to organic phase ratio 1 : 1, reaction temperature 25°C, the rate of chloride addition about 10 min, and molar ratio of the reagents diol/acid dichloride 1 : 1.1, benzene‐hexane as an organic phase. To determine the optimal conditions for interfacial polycondensation, the influence of the following factors on yield and value of reduced viscosity were studied: organic phase, excess of sodium hydroxide as an acceptor of HCl, contribution of benzyltriethylammonium chloride as a catalyst, and contribution of an emulsifier, Mersolan. The structure of all polyesters was determined by elemental analysis and infrared spectra. Initial decomposition and initial intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Some mechanical and electrical properties of isophthaloyl polyester, only partly soluble in organic solvents, were determined.

Phase transfer catalysis: Kinetics and mechanism of hydroxide ion initiated dichlorocarbene addition to styrene catalysed by triethylbenzylammonium chloride

The kinetics of dichlorocarbene addition to styrene was studied under phase-transfer catalytic conditions using aqueous sodium hydroxide as the base and triethylbenzyl ammonium chloride as the phase-transfer catalyst. The reaction was carried out at 40°C under pseudo first-order condition by keeping aqueous sodium hydroxide and chloroform in excess. The fiogress of the reaction was monitored by gas chromatography. The effects of various experimental conditions on the rate of the reaction were studied and based on the results obtained a suitable mechanism has been proposed.

Convenient and Efficient Tosylation of Oligoethylene Glycols and the Related Alcohols in Tetrahydrofuran–Water in the Presence of Sodium Hydroxide

Abstract Oligoethylene glycols and some related alcohols were efficiently tosylated with p-toluenesulfonyl chloride in a tetrahydrofuran–water (1:1) mixture in the presence of excess sodium hydroxide. This method is advantageous over the conventional tosylation in pyridine both regarding the work-up procedure, the yield, and the purity of the product, and may be potentially useful for the tosylation of certain acid-labile alcohols.

Determination of thiamine using continuous flow molecular emission cavity analysis

A continuous flow method for the determination of thiamine hydrochloride (20.0-240.0 microgram ml(-1), 5.9 x 10(-5)-7.1 x 10(-4)m) is described. The sample was mixed with an excess of sodium hydroxide and remained in the delay coil for 20 min at 90 degrees C. The solution was then mixed with an excess of orthophosphoric acid and the hydrogen sulphide evolved was transferred continuously into the cavity to generate a molecular++ emission of S2. The analysis is completely automated, requires no sample pre-treatment and samples can be analysed at a rate of 30 samples h(-1) with a relative error of 1-2%. The method was evaluated by carrying out an interference study with common excipients and other water-soluble vitamins, a recovery study and by the analysis of commercial formulations. Results compared well with those obtained using the official method. The method was also applied to content uniformity tests.

Sulfur-33 NMR of Benzenesulfonic Acid

For the general use of sulfur-33 NMR spectroscopy, measuring conditions for benzenesulfonic acid were examined. A 0.75M solution (deuterium oxide-water mixture in the ratio of 2: 1) adjusted to pH 6.5-10.5 gave a good signal with line width at half the peak height of 13.5Hz after 3h of data accumulation. The chemical shift [-11.5ppm relative to (NH4)2SO4] did not vary with this pH range. Hardly any signal could be observed at a pH less than 3.6. Slight lowering of S/N ratio and minor line-broadening were caused by the addition of excess sodium hydroxide (pH>14). Thus possibly, tuning of the probe and use appropriate pulse conditions are essential for measuring sulfur-33 NMR, and the sample solution of sulfonic acids should be made neutral or alkaline.

Quantitative treatment of cationic surfactant catalyzed alkaline degradation of polyester

Abstract In order to study the role of cationic surfactant in the rate enhancement of reaction, the alkaline degradation of polyester was performed in the presence of excess sodium hydroxide and higher bath ratio solutions at 95°C, using cetyl benzyl dimethyl ammonium chloride as a catalyst. The kinetic rate constants of reaction were determined, and treated quantitatively by a pseudo phase model. It was suggested that the role of cationic surfactant in the rate enhancement was to provide a pseudo phase for reaction by binding itself to the fiber.

Linear polythioesters. X. Products of interfacial polycondensation of bis(4‐mercaptophenyl)ether with izomeric phthaloyl chlorides

AbstractNew polythioesters were obtained by interfacial polycondensation of bis(4‐mercaptophenyl)ether with phthaloyl, isophthaloyl, and terephthaloyl chlorides. To determine the optimal conditions for interfacial polycondensation, the influence of the following factors on yield and value of reduced viscosity were studied: organic phase, 100% excess of sodium hydroxide, contribution of benzyltriethylammonium chloride as a catalyst, and the temperature of the reaction. A thorough examination of the process was carried out only for polycondensation of dithiol with phthaloyl chloride. Yield of all reaction products as well as reduced viscosity of only polythioesters from dithiol and phthaloyl chloride were found because these were the ones which were soluble in tetrachloroethane. The structure of all polythioesters was determined by elemental analysis and infrared spectra. Initial decomposition and initial intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Some mechanical and electrical properties of polythioesters were determined.

Swelling of carboxyl-containing copolymer latexes

Methacrylic acid copolymers (5–50%) with methyl methacrylate, styrene, and 2-ethylhexyl acrylate were prepared at 60°C by batch and semicontinuous emulsion polymerization, and the latexes were neutralized with sodium hydroxide. In some cases, ethyl acrylate or crosslinking monomers such as ethylene glycol dimethacrylate, divinylbenzene, or trimethylolpropane triacrylate were added to the recipe. The parameters varied included the Tg of the copolymer, the hydrophobicity of the base monomer, the carboxyl group distribution within the particle, and the degree of crosslinking. The variation of particle size with pH was determined using dissymmetry of light scattering, the variation of viscosity with pH using the Weissenberg Rheogoniometer in the cone-plate mode, and the loci of the carboxyl groups by a modified conductometric titration method. The serum was separated from the latex particles by serum replacement, an excess of sodium hydroxide was added to the cleaned latex, and the conductance and unreacted sodium hydroxide were measured as a function of time. The carboxyl groups were arbitrarily divided into: (i) the particle surface neutralized instantaneously; (ii) the first subsurface layer neutralized within 10 minutes; (iii) the second subsurface layer neutralized within 24 hours; (iv) the unneutralized particle core; (v) the latex serum. The three characterization techniques gave a detailed analysis of the swelling behavior of the carboxyl-containing copolymers. The swelling upon neutralization of the relatively hydrophilic methyl methacrylate copolymers was higher than that of the relatively hydrophobic styrene and 2-ethylhexyl acrylate copolymers. Batch polymerization of the methyl methacrylate copolymers gave a higher concentration of carboxyl groups at or near the particle surface; semicontinuous polymerization gave a more uniform distribution throughout the particle. Decreasing the Tg of the copolymer increased the concentration of carboxyl groups at or near the particle surface. Crosslinking of the particle had little effect on the carboxyl group distribution.

Reaction calorimeter for applications in chemical process industries: Performance and calibration

Two types of reaction calorimeter for use in evaluation of thermai data for plant design and assessment of thermal safety in the chemical process industries have been developed. The principle of calorimetric measurement is thermoelectrical compensation of the heat of reaction. One calorimeter is built in stainless steel, the other in glass. Reactor volumes are 200 to 1400 ml. Practicable temperature range is about −50°C to +200°C and admissible pressures range from 0 to 50 bars. For the chemical calibration of these reaction calorimeters the neutralization reaction of sulfuric acid in excess sodium hydroxide has been chosen. A calibration curve in a appropiate concentration range has been established by precision calorimetry and can be used now as a reference of sufficient accuracy.

Friedel‐Crafts‐Acylierungen aliphatischer Verbindungen. VII. Friedel‐Crafts‐Acylierungen von Carbonsäurechloriden mit Maleinsäureanhydrid ‐ ein neuartiger Zugang zu Tetronsäuren

Friedel‐Crafts‐Acylations of Aliphatic Compounds. VII. Friedel‐Crafts‐Acylations of Carboxylic Acid Chlorides with Maleic Acid Anhydride — a New Access to Tetronic AcidsReaction of succinic acid with propionyl chloride under Friedel‐Crafts‐reaction conditions yields 2‐methyl‐cyclopentan‐1,3‐dione. The related reaction of maleic acid anhydride with propionyl chloride does not yield 2‐methyl‐cyclopent‐4‐en‐1,3‐dione 7, but a E/Z‐mixture of the lactones 5 and 8. By treating with hydrogen chloride in methanol or with thionylchloride in methanol the lactone mixture is converted to dimethyl (2Z, 4E)‐3‐hydroxy‐2‐methyl‐hexa‐2,4‐diendioate 10. By reaction with excessive sodium hydroxide the mixture of lactones is transformed into tetronic acid 11. Structure determinations are based on u.v.‐, i.r.‐, m.s.‐ and n.m.r.‐spectroscopy and on further chemical transformations. This tetronic acid synthesis represents an intramolecular addition of a carboxylate anion to an α, β‐unsaturated carbonyl compound.

Bilirubin acidity. Titrimetric and 13C NMR studies.

Acidimetric titration of bilirubin IX-alpha, dissolved in excess aqueous sodium hydroxide, showed that two protons are dissociated with pK values well below 7 and that one or several additional acidic groups titrate with pK around 12.9. Precipitation of the nearly insoluble acid precluded determination of the two lower pK values by titration in aqueous solution. In dimethyl sulfoxide solution, four acidic protons were demonstrated, titrating two by two without precipitation. 13C NMR spectra of bilirubin IX-alpha were recorded and complete assignments were made by comparison with the spectra of bilirubin XIII-alpha and mesobilirubin etc. Such spectra, recorded after addition of 2 and 4 mol of base per mol of bilirubin IX-alpha, showed that both carboxyl groups are titrated by the first 2 mol of base, and both lactams by the following 2 mol of base. Cotitrations of bilirubin IX-alpha with other acids, o- and m-hydroxybenzoic acid and 2-pyridone, were used to determine relative pK values in dimethyl sulfoxide solution, and pK values for the four acidic protons of bilirubin IX-alpha in aqueous solution were calculated from the Born equation. Both carboxyl groups exhibited pK = 4.4, and both lactams pK = 13.0, in good agreement with values expected from the chemical structure of the bilirubin molecule. The implications of these findings for understanding the mechanism of bilirubin neurotoxicity are discussed.

Effect of drag-reducing additives on the rate of mass transfer in diffusion-controlled electrochemical processes

Mass transfer between a rotating cylinder and a solution containing sodium carboxymethyl cellulose polymer, was studied using an electrochemical technique involving the reduction of potassium ferricyanide in a large excess of sodium hydroxide. The Reynolds number and polymer concentration were varied over the ranges 4100–41 000 and 10–500 ppm, respectively. Under these conditions, it was found that polymer addition reduces the mass transfer coefficient by 10–22% depending on Reynolds number and polymer concentration. The mass transfer data in polymer-containing solutions were found to fit the equation (St) = 0.07(Re)−0.3(Sc)−0.644.

Carbon-13 NMR Spectra of Benzene Mono- and Di-Carboxylic Acids and Their Analytical Applications

Abstract Carbon-13 NMR spectra of benzoic, and phthalic acids were compared both in D2O with an excess of sodium hydroxide and in a mixture of DMSO-d6 and H2O (4:1). Tight ion pair forms of benzoate anion were considered. A simple additive rule for isomeric phthalic acids was employed to assign the spectral peaks. These carboxylic acids gave characteristic peaks and so can be distinguished from others in mixtures. Quantitative analyses of these carboxylic acids with calibration curves are also possible by a simple preparation of basic D2O solutions. An example of the use of these data is the Henkel process (cf. Fig. 1) for the synthesis of terephthalic acid.

ChemInform Abstract: CYCLONUCLEOSIDES RELATED TO ADENOSINE AND TUBERCIDIN

AbstractDas Adenosinderivat (I) gibt mit einer äquimolaren Menge NaOH das Cyclonucleosid (II), das mit NaOH‐Überschuß weiter zum Imidazol‐Cyclonucleosid (III) reagiert.

Cyclonucleosides Related to Adenosine and Tubercidin

Treatment of N6,N6-dibenzoyl-2′,3′-O-isopropylidene-5ʹ-O-mesyladenosine (IV) with an equimolar amount of sodium hydroxide afforded a cyclonucleoside, IX, which was furthur converted to an imidazole cyclonucleoside, VI, with excess sodium hydroxide. In aqueous acetic acid VI was converted to a cyclonucleoside, XIII, which suffered from furthur degradation on mild alkaline hydrolysis giving a cyclonucleoside, XIV. In the tubercidin (7-deaza-adenosine) series the reaction proceeded analogously.

The preparation of crystalline polypropylene sodium sulfonates and their interaction with an included sodium hydroxide phase

AbstractSodium sulfonated polypropylenes have been prepared by the slurry chlorosulfonation of polypropylene or propylene—ethylene copolymer followed by hot aqueous sodium hydroxide treatment. Low levels of excess sodium hydroxide were added to the materials to stabilize them against thermal decomposition. It was found that there was a strong interaction between the sodium hydroxide phase and the polymer sodium sulfonate groups which persisted above the nominal melting point of crystalline polypropylene. Evidence for the interaction includes an increased melt viscosity and a greatly increased nucleation rate for the composites as compared to the polypropylene sodium sulfonates not containing the sodium hydroxide phase. The composites have an improved balance of mechanical properties as compared to the materials from which they are prepared.

Base-promoted rearrangement of 2,3,5,6-tetrachloropentacyclo-[5.4.0.02,6.03,10.05,9]undecane-4,8,11-trione

Reaction of the title compound (III) with an excess of sodium hydroxide in refluxing toluene results in a novel rearrangement, affording 6-chloro-cis-1,2-dihydrobenzocyclobutene-1,2,3-tricarboxylic acid (IVa).

Cyclonucleosides Related to Adenosine and Tubercidin

Treatment of N6,N6-dibenzoyl-2′,3′-O-isopropylidene-5ʹ-O-mesyladenosine (IV) with an equimolar amount of sodium hydroxide afforded a cyclonucleoside, IX, which was furthur converted to an imidazole cyclonucleoside, VI, with excess sodium hydroxide. In aqueous acetic acid VI was converted to a cyclonucleoside, XIII, which suffered from furthur degradation on mild alkaline hydrolysis giving a cyclonucleoside, XIV. In the tubercidin (7-deaza-adenosine) series the reaction proceeded analogously.

The enthalpy of solution of gaseous hydrogen fluoride in water at 25 °C

Gaseous hydrogen fluoride was dissolved directly in excess sodium hydroxide in a calorimeter. To reduce the magnitude of the corrections to the ideal gaseous state, the gas was introduced at pressures of about 350 and 150 Torr in two sets of measurements. At 25 °C, the standard enthalpy of solution for HF(g) = (H+ + F-)(aq) was found to be -(14.72±0.10) kcal mol−1.