Reaction of 3-aryl-2-benzoyloxiranes with alkyl thiocyanates

3-Aryl-2-benzoyloxiranes and alkyl thiocyanates in the presence of an equivalent amount of anhydrous AlCl₃ form erythro-N-(2-benzoyl-l-aryl-2-chloroethyl)-S-alkyl thiocarbamates and -diketones. p-Toly1- and p-anisy1-2-benzoy1-oxiranes do not react with alkyl thiocyanates, but isomerize to the respective -diketones, and form the threo-chlorohydrins in low yield.Translated from Khimiya Geterotsilklicheskikh soedinenii, No. 12, pp. 1624–1628, December, 1985.     

Reaction of perfluoroalkylcarbanions with thiocyanates

A nucleophile can attack a thiocyanate either on the sulfur atom or on the cyanide group. In the former case the product is a sulfide, in the later one a nitrile.Our goal was to study this reaction with perfluoroalkyl carbanions. Linear, ramified and cyclic magnesium or potassium anions were examined. It appears that, independently of the nature of the R group (CH₃, C₆H₅CH₂, C₆H₅), attack occurs on the sulfur atom leading only to the formation of sulfides.

In the case of RC₆H₅CH₂, cleavage of the sulfide by chlorine gives mainly the corresponding perfluoroalkylsulfenyl chloride.     

The derivatization of fatty acids by (chloro)alkyl chloroformates in non-aqueous and aqueous media for GC analysis

Fatty acids can be conveniently derivatized in less than one minute with (chloro)alkyl chloroformates such as methyl chloroformate, 2-chloroethyl chloroformate and 2,2,2-trichloroethyl chloroformate. 2,2,2-Trichloroethyl chloroformate is the most reactive reagent, and yields a reaction product which can be sensitively detected by GC ECD (detection limit 50 ng/ml, i.e. 25 pg/injection, for C⁸, C¹⁰, and C¹² acids). In non-aqueous media 3-picoline, N-methylpiperidine, and dimethylaminopyridine show catalytic activity comparable with that of pyridine and can, therefore, replace it. N-methylpiperidine is the best basic catalyst in aqueous media (i.e. media containing up to 40 % water).     

Polymerizations with hydrido and alkyl transition metal complexes in aqueous media

Hydrido pentacyanocobaltate(III) and alkyl pentacyanocobaltate(III) have been studied as initiators for the polymerization of isoprene and butadiene in aqueous emulsion systems. The microstructure of the polymers is consistent with a free radical process. Other transition metal hydrides are relatively ineffective as polymerization initiators or act as inhibitors for the radical polymerization of the same dienes.     

FIA titrations of phenothiazine derivatives in aqueous micellar and non-aqueous media

New methods of flow injection analysis (FIA) neutralization titrations of phenothiazine derivatives in aqueous micellar medium of a cationic surfactant using potentiometric and spectrophotometric detection were proposed; titrations with a mixing gradient chamber and high-speed titrations were compared. The FIA titration method in non-aqueous media based on an official method of determination (titration with perchloric acid in anhydrous acetic acid) was also developed. Under optimized reaction conditions and flow-through parameters, the calibration range and equations, the sensitivity, and the repeatability of all methods were found and discussed. All titrations were assayed for medicinal forms.     

Reaction of sulfolene oxides with thiocyanates

The reaction of oxides of sulfolene and its methyl derivative with potassium and sodium thiocyanates was studied. It is shown that under the influence of potassium thiocyanate these oxides undergo isomerization to the corresponding unsaturated alcohols. In the presence of sulfuric acid, however, the oxides react with sodium thiocyanate to give addition products, viz., hydroxythiocyanatosulfolanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1333–1334, October, 1982.     

Some observations on monomer reactivity ratios in aqueous and non-aqueous media

Reactivity ratios have been determined for free radical copolymerization of n.butyl acrylate (BA) with N-vinyl-2-pyrrolidone (VP) at 65°C in bulk and in the presence of water. For 0 to 30% by weight of water in the feed, the value of r_VP was sensibly constant (∼ 0.03 ± 0.03). The value of r_BA also underwent virtually no change (∼ 0.90 ± 0.05) at water contents from 0 to 22% by weight but increased to 3.7 at 25% water and to 6.3 at 30% water. These findings are not amenable to satisfactory explanation but one aspect of possible relevance is proposed tentatively.     

Reactions of alkyl diazoacetates with pyridinium ylides

Pyridinium (methoxycarbonyl)methylide generated from (methoxycarbonyl)methyl-pyridinium halides under the action of K₂CO₃ reacts with alkyl diazoacetates in CH₂Cl₂ at 20 °C, resulting in the successive addition of three CHCOOMe fragments from the ylide to form 3,6-bis(alkoxycarbonyl)-4,5-diazaoctadienoic acid diesters. Heating of the latter in the presence of pyridine leads to their isomerization to give tetraalkyl tetrahydropyridazine-tetracarboxylates in high yields. Under more drastic conditions (refluxing xylene in the presence of pyridine), the acyclic tetraesters undergo another transformation to form pyrrole-tetracarboxylic acid esters in yields of up to 60%. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 984–988, April, 2005.     

Dichloramine-B as redox titrant in non-aqueous or partially aqueous media

Dichloramine-B is proposed as a redox titrant in glacial acetic acid medium. The general conditions for its use and the procedures for estimating hydrazine, ascorbic acid, ferrocyanide, hydroquinone, oxine, antimony(III) and thallium(I) potentiometrically and allyl, crotyl and cinnamyl alcohols by a back-titration procedure are described.     

Dichloramine-T as a new oxidimetric titrant in non-aqueous and partially aqueous media

A new oxidimetric titrant, dichloramine-T, is proposed for redox titrations in glacial acetic acid medium. The general analytical conditions for using this oxidant and the procedures for potentiometric determination of ascorbic acid, iodide, arsenic(III) and iron(II) are described.     

Thermometric titration of some monoprotic and diprotic acids in aqueous and non-aqueous media

Some mono- and diprotic acids have been titrated thermometrically with strong alkalis in aqueous and non-aqueous media. Thermograms with sharp arrest points were obtained, from which heats of neutralization were measured. Heats of neutralization in the media used were compared and an effect attributable to hydrogen bonding was found.     

A practical method for synthesis of stable phosphorus ylides in aqueous media

A convenient one-pot synthesis of stable phosphorus ylides by the condensation of triphenylphosphine with dialkyl acetylenedicarboxylate and CH acids, such as penta-2,4-dione or diethyl propane-1,3-dioate, in the presence of -cyclodextrin as a catalyst (to increase the solubility of the reactants in water) without using toxic organic solvents was proposed. This methodology is of interest due to the use of water as a solvent, thus minimizing such factors as the cost, operational hazards, and environmental pollution.     

Reaction of thiocyanates with ironcyanogen compounds of silver

Silver fenocyanide as well as Silver ferricyanide are converted into silver thiocyanate by treating with thiocyanate ions, while feirocyanide ions or ferricyanide ions are formed at the same time. Silver ferrocyanide as well as silver ferricyanide are dissolved by solutions of thiocynates of higher concentrations.     

Cerimetry in non-aqueous media

Summary It was found that ceric oxalate is an intermediate product in the oxidation of oxalic acid by ammonium hexanitrato cerate in solvents such as acetonitrile, and a mixture of acetonitrile and glacial acetic acid. Conditions for the formation of ceric oxalate and its decomposition into carbon dioxide and cerous oxalate have been studied. An analytical method for the estimation of oxalic acid in non-aqueous media has been evolved based on this reaction.

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Zusammenfassung Es wurde festgestellt, daß bei der Oxydation von Oxalsäure mit Ammoniumhexanitratocerat(IV) in Acetonitril oder einem Gemisch von Acetonitril und Essigsäure Cer(IV)-oxalat als Zwischenprodukt auftritt. Die Bedingungen für die Bildung von Cer(IV)-oxalat und seine Zersetzung zu CO₂ und Cer(III)-oxalat wurden untersucht. Ein Verfahren zur Oxalsäurebestimmung in nichtwäßrigem Medium wurde ausgearbeitet.

     

Dibromamine-B as a new redox titrant in non-aqueous or partially aqueous media

A new redox titrant, dibromamine-B (N,N'-dibromobenzene sulphonamide) is introduced for use in acetic acid medium. Direct potentiometric determinations of hydrazine, ascorbic acid, aniline, thiourea and its metal complexes and oxine and its metal complexes have been described.     

Photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine in aqueous and non-aqueous media

The photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine (SiPcS₄ and GePcS₄) in aqueous solution (phosphate-buffered saline (PBS) solution, pH 7.4) (in the presence and absence of cremophore EL (CEL)) and in dimethylsulphoxide (DMSO) were studied. The complexes have intense absorption in the visible/near-IR region though they highly aggregate in aqueous solution with a dimerization constant of 2 × 10⁴ dm³ mol⁻¹. The fluorescence excitation spectra however have only one band suggesting that only the monomer fluoresces. Both the quantum yields of the triplet state (Φ_T) and the triplet lifetimes (τ_T) were found to be higher in DMSO compared to in aqueous solution. Aggregation is hindered by addition of cremophore EL in aqueous solution and this induced disaggregation caused an increased Φ_T and τ_T probably due to the reduced interaction of the phthalocyanines with the aqueous medium in the presence of CEL.     

The kinetics of charging and discharging of iridium oxide films in aqueous and non-aqueous media

Cyclic voltammetry and chronocoulometry have been used to investigate the kinetics of oxidation and reduction of electrochenucally generated Ir oxide films in H₂SO₄(aq), basic aqueous LiClO₄ solutions and LiClO₄ + acetonitrile solutions. In acidic aqueous solutions, the scan rate at which the main anodic peak potential begins to shift positively in cyclic voltammetry experiments has been used as a parameter to assess the charging and discharging kinetics of Ir oxide films grown under various conditions. In acidic and basic aqueous solutions, chronocoulometric measurements indicate that electron transport through the oxide is rate limiting for the main redox wave, whereas ion transport probably limits the charging/discharging kinetics in LiClO₄ + CH₃CN solutions. In this non-aqueous medium, it appears that ca. 35% of the oxide sites charge and discharge approximately an order of magnitude more rapidly than the remaining sites.     

Reaction of alkyl halide salts of nitrogen-containing heterocycles with sulfur dioxide in aqueous solutions

Complexes of quaternary salts with SO₂ are formed on saturation of aqueous solutions of alkyl halide salts of nitrogen-containing heterocycles with sulfur dioxide. The SO₂ concentration necessary for the precipitation of the complexes increases in the order I < Br < Cl and decreases as the alkyl group attached to the nitrogen becomes larger. The sulfur dioxide in the complexes is bonded through the halide ion by a charge-transfer coordinate bond, and their separation into an independent phase is due to a change in the degree of hydration during complexing. Several crystalline adducts are described, and the autooxidation of the SO₂ complex of pyridine methiodide is investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 966–969, July, 1972.