Methanol In Alkaline Solution Research Articles

Electrochemical synthesis of pyrido[1,2-a]pyrimidine derivatives. II. Electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4H-pyrido[1,2-a]pyrimidine in aqueous media

The electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4H-pyrido[l,2-a]pyrimidine (base and HCl salt) was investigated by polarography and controlled potential electrolysis in aqueous buffered solutions at different pH values on a dropping mercury electrode and a mercury pool cathode. Controlled potential electrolyses performed in methanolic borate buffer solution (pH=9, 10) at the first polarographic wave (1.45 V vs SCE) gave a stable C-8-coupled hydrodimer (III) in a one-electron process with a product yield of 52%. Reduction performed in alkaline methanolic solution (pH=13.4), at the second polarographic wave (− 1.86 V vs SCE) showed a dihydromonomer (IV) formation with a product yield of 87%, in a two-electron process.

CONVENIENT PREPARATION AND SPECTROSCOPIC STUDIES OF SULFOXIMINES AND SULFONEDIIMINES:N-CHLOROSULFILIMINE AS KEY INTERMEDIATE

Abstract N-Unsubstituted sulfilimines, when reacted with sodium hypochlorite in an aqueous alkaline methanol solution or with Chloramine-T in dry acetonitrile in the presence of excess sodium salt of tosylamide were converted to the corresponding N-unsubstituted sulfoximines (1) or mono-N-tosylsulfonediimines (2) in good yields. 2 gave the unsubstituted sulfonediimines (3) in high yields upon treatment with conc. H2SO4. N-Chlorosulfilimine (5) was isolated in the initial stage of these reactions. 5 was found to react with NaOH in aqueous methanol and also with anhydrous Chloramine-T in dry acetonitrile to yield the corresponding 1 and 2 in good yields. IR, NMR, and Mass spectroscopic studies of 1, 2, and 3 were also carried out.

A cis-trans equilibrium isotope effect in arylcyanomethylenepyrrolidinones

The equilibration of three 5-arylcyano-methylene-3,4-dimethylpyrrolidin-2-ones in alkaline methanolic solutions by exchange of the C-3 hydrogen atoms yields different [cis]/[trans] ratios for C-3-protiothan for the C-3 deuterio-compounds.

An investigation of anthraquinone-catalysed alkaline pulping via component modeling and electron spin resonance experiments

The radical anion of anthraquinone (AQ•−) has been generated by the reduction of anthraquinone (AQ) with sugars in aqueous alkaline solution. This appears to be the first time that the radical has been observed (esr spectrometry) in an entirely aqueous medium. Alkaline methanol solutions of AQ, when irradiated with light, yielded colourless solutions also exhibiting strong esr signals characteristic of. AQ•−.The ability of various carbohydrate and lignin preparations to reduce AQ, or to oxidize the reduced forms of AQ, was also investigated, both by direct observation and by electrode potential measurements. In very concentrated alkali, AQ was reduced by glucose to a green solid thought to be a quinhydrone.

Selective electroreduction of dinitrogen on a rotating copper amalgam electrode

On an amalgamated rotating copper disk electrode in an alkaline methanol solution in the presence of mixed Ti(OH)3−Mo(III) hydroxide, dinitrogen is shown to be selectively electroreduced to hydrazine in the potential range −1.6 to −1.9 V (with respect to the saturated calomel electrode).

Electroreduction of dinitrogen in a Ti(III)−Mo(III)-guanidine system

Dinitrogen reduction on a mercury cathode has been studied in an alkaline methanol solution with guanidine buffer (pK=13.6) in the presence of homogeneous catalysts (alkoxy complexes of Mo(III) and Ti(III). As is found, dinitrogen electroreduction occurs on the electrode surface. The reaction rate is determined by the rate of electron transfer.

Electrocatalytic properties of the Ti(OH)3−Mo(III) system in the reduction of molecular nitrogen

Electrochemical reduction studies of dinitrogen catalyzed by Ti(OH)3−Mo(III) in an alkaline methanol solution on a mercury cathode show that the maximum yield of hydrazine (4%) and ammonia (43%) is observed at 0.5 mA/cm2 current density. In experimental conditions it corresponds to the zero-charge potential of sodium amalgam (−1.86 V).

CO activation in the reactions of iron carbonyls and alkynes. Syntheses, crystal structures, and nuclear magnetic resonance studies on hydroxyferrole and maleoyliron derivatives

New syntheses are described for the complexes [Fe2(CO)6{C4(OH)2RR′}](‘sawhorse’ geometry), and [Fe(CO)4-{(CO)2C2RR′}]; the former are obtained in anhydrous hydrocarbon solvents, and the latter in alkaline methanolic solutions. The structures of [Fe2(CO)6{C2(OH)Et}2] and [Fe(CO)4{(CO)2C2Et2}] have been determined by X-ray diffraction methods; crystals of the binuclear derivative are monoclinic, space group P21/c, with Z= 4, in a unit cell of dimensions: a= 13.392(8), b= 16.242(9), c= 7.617(8)A, β= 96.05(8)°; crystals of the mononuclear derivative are tetragonal, space group I41/a with Z= 16, in a unit cell of dimensions: a= 20.819(12), c= 12.950(9)A. The structures have been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.038 and 0.036 respectively. Both complexes contain a five-membered heterocyclic ring formed upon CO activation. The 1H and 13C n.m.r. spectra indicate CO fluxionality in the binuclear derivative. Chemical and structural relationships between these complexes are discussed and some comments made on CO activation, in the formation of the heterocyclic rings.

Treatment of Lactose with Alkaline Methanolic Solutions: Production of Beta-Lactose from Alpha-Lactose Hydrate

Crystallization of lactose from methanolic solutions of sodium hydroxide can be used to prepare β-lactose from α-lactose hydrate. Conversion of 90 to 93% α-lactose hydrate to β-lactose can be achieved by 2h refluxing with any ratio of lactose to methanol as long as the methanol contains from .02 to .06% (wt/vol) sodium hydroxide and less than 13% (wt/wt) moisture. At room temperature, conversion was complete in 10h at all ratios of α-lactose hydrate to methanol containing from .1 to .3% (wt/vol) sodium hydroxide and no more than 3% (wt/wt) moisture. The conversion of α-lactose hydrate to β-lactose ceased when moisture was above 3.5% (wt/wt) at room temperature and 13% (wt/wt) at reflux. With sodium hydroxide concentrations above .06%, at reflux, or above .3% at room temperature, alkaline rearrangement took place, and lactose was converted into a yellow mixture of degradation products.

ChemInform Abstract: SYNTHESES OF 3,4‐DIMETHYLPYRROLE

AbstractDie Umsetzung der Sulfinylamide (I) mit dem Butadien (II) führt zu den Cycloaddukten (III), aus denen durch Erhitzen in methanolischer, stark alkalischer Lösung die Titelverbindung (IV) erhalten wird.

Syntheses of 3,4-Dimethylpyrrole

Abstract Treatment of N-sulfinyl compound with 2,3-dimethylbutadiene gives a cycloadduct which affords 3,4-dimethylpyrrole in satisfactory yields by heating in a strongly alkaline methanolic solution.

Photosensitized formation of hydrogen peroxide in strongly alkaline methanolic solutions

Photosensitized formation of hydrogen peroxide in strongly alkaline methanolic solutions

Determination of Coumarin and Umbelliferone Mixtures in Whole Blood by Spectrophotofluorometry

AbstractA spectrophotofluorometric method is described for the quantitative analysis of coumarin, urabelliferone, and mixtures thereof in whole blood. The two drugs were selectively isolated from blood by solvent extraction. Analysis of the isolated coumarin was based on the measurement of the fluorophore at activation and emission wavelengths of 361 and 491 nm, respectively. The fluorophore was obtained by irradiating an alkaline methanolic solution of the drug with UV light. A linear relationship between fluorescence and concentration existed over the concentration range of 0.02–0.2 μg of coumarin/ml. A mean recovery value of 94.8% was obtained from whole blood. The isolated umbelliferone was determined according to established methods at activation and emission wavelengths of 370 and 450 nm, respectively, and the limit of detection was 10 times more sensitive than previously reported. A linearity response was obtained between 1 and 10ng of umbellif‐erone/ml. Good recovery data for mixtures of coumarin and umbelliferone in whole blood were obtained.

Pulse radiolysis of methanol and ethanol. Acid-base behaviour of hydroxymethyl and hydroxyethyl radicals

Pulse radiolysis of N2O saturated alkaline methanolic and ethanolic solutions indicates that at room temperature the equilibria R1R2ĊOH + R1R2CHO–⇌ R1R2ĊO–+ R1R2CHOH (2) are rapidly established with K2= 2120 ± 235 and 3280 ± 340 for ·CH2OH and CH3ĊHOH radicals in their respective parent solvents. The decays of the radical anions obey second-order rate laws in both solvents and rate constants have been obtained for the bimolecular reactions involving the neutral and basic forms of the radicals.Experiments with ethanolic acetaldehyde solutions indicate that k–2 > 6 × 106 dm3 mol–1 s–1 and hence k2 > 1.8 × 1010 dm3 mol–1 s–1.

RADIOLYTIC DECHLORINATION OF POLYCHLORINATED BIPHENYLS (PCB) IN ORGANIC SOLUTIONS

Abstract The radiolytic dechlorination from PCB in organic solutions, has been studied. The chain reaction does not occur in neutral alcoholic solutions and alkaline methanol solution but occurs in alkaline 2-propanol solutions, and G(Cl−) reaches about 450 at 5×10−2 M potassium hydroxide concentration.

PHOTOCHEMICAL OXIDATION OF 6,6-DIMETHYLFULVENE IN ALKALINE METHANOLIC SOLUTION

Abstract Both direct and sensitized photooxidations of 6,6-dimethylfulvene in alkaline methanolic solutions gave, in addition to two methanol addition products of 5-isopropylidene-4-hydroxy-2-cyclopentenone: 2-isopropenyl- (5∼12 %) and 2-(2’-methoxyisopropyl)- (21∼28 %) 4-methoxy-2-cyclopentenones, α-furyl isopropyl ketone (3 %) which would be presumably formed via rearrangements of the intermediates postulated previously for the formation of the oxepinone and 4-hydroxymethylenecyclopentenone derivatives.

The Radiolysis and Photolysis of Methanolic Solutions of Eosin. I. The γ-Radiolysis of Neutral and Alkaline Solutions

Abstract The γ-radiolysis of eosin has been studied in deaerated neutral and alkaline methanolic solutions. Eosin is reduced principally with CH2OH radicals in dilute solutions. In neutral solutions, G(–eosin) is about 2 at the eosin concentration of 10−5m and increases as the concentration of eosin is increased. The final products are leuco-eosin and an unidentified substance which has an absorption peak at 455 nm. In an alkaline solution (10−5m), G(–eosin) is about 4 and the product is semireduced eosin, which is stable in the dark and which undergoes photo-debromination. The ESR spectrum of semireduced eosin has also been recorded. Comparative studies have also been made on uranin solutions.

The Radiolysis and Photolysis of Methanolic Solutions of Eosin. II. The Photo-Debromination of Eosin in an Alkaline Solution

Abstract Semireduced eosin was found to undergo photo-debromination and was identified with a precursor in the photo-debromination of eosin in alkaline methanolic solutions. Semireduced eosin was prepared by the γ-irradiation of an eosin solution. The photolysis of semireduced eosin was investigated by the use of continuous and flash light. From the absorption spectral change and a study of the decay, the mechanism of the photo-debromination was proposed. The debromination process of the photo-excited semireduced eosin was explained satisfactorily by assuming the transient formation of the debrominated-eosin σ-radical as an intermediate. In addition, we found an electron-transfer reaction from semireduced debrominated eosin to eosin, which results in the formation of semireduced eosin and debrominated eosin in the dark. A general conclusion as to the photo-dehalogenation of xanthene dyes is also given.

Mechanism of the electrooxidation of methanol on a smooth platinum electrode in alkaline solution

1. The proposed mechanism of the electrooxidation of methanol on a platinum electrode explains the formation of various chemisorbed particles and various products of electrooxidation in alkaline and acid solutions under stationary conditions. 2. In alkaline solution, in contrast to acid solution, a process of catalytic decomposition of methanol, parallel to the electrooxidation of chemisorbed particles, takes place on a platinum electrode at high concentrations of methanol and at low anodic potentials. 3. The apparent activation energy of the electrooxidation of methanol in alkaline solutions is lower than in acid solutions at the same p'otentials.

TLC-fluorimetric analysis for atmospheric scopoletin

The evidence for the presence of scopoletin in airborne particulates, house dust, and coffee roast effluents consists of R f values obtained with silica gel thin-layer chromatography and mobility values obtained with paper electrophoresis, as well as fluorescence spectra obtained from the chromatogram and from methanolic, alkaline methanolic, and sulfuric acid solutions. By a procedure involving TLC SPF, scopoletin has been assayed in these various samples. Recovery of scopoletin from enriched airborne particulates was 97%. These various separations and fluorimetric examinations have shown that a large number of unknowns was also present in these samples.