Dimerization of methyl isothiocyanate to the 2-mercapto-1-methylimidazole-5(4H)-thione anion under the action of a superbase

Dimerization of methyl isothiocyanate under the action of potassium diisopropylamide followed by alkylation of the intermediate dithiolate gives 2,5-bis(alkylthio)-1-methylimidazoles in 71–74% yields. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 186–187, January, 1998.     

Synthesis of 1,3,4,2,6-oxathiazadiphosphorines

Alkyl chlorides and 6-alkoxy-2,4-bis(diethylamino)-6-oxo-1,3,4,2,6-oxathiazadiphosphorines are the products of the reaction of tetraethyldiamidochlorophosphite with dialkylisothiocyanatophosphates. The structure of the oxathiazadiphosphorines was demonstrated by IR,¹H,¹³C,³¹P NMR, and mass spectroscopy and it was found that they are formed as a mixture of two geometric isomers.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific-Center, Russian Academy of Sciences, 420083 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1168–1171, May, 1992.     

Holographic relaxation spectroscopic study on the structure of gelatin gel doped with fluorescein as a tracer

The structures of gelatin gels have been studied by holographic relaxation spectroscopy (HRS) with fluorescein as a doped tracer. An HRS spectrum with double peaks has been observed. It has been experimentally proven that this anomalous HRS spectrum is related to the structures of the gelatin gels. It is shown that two kinds of gel networks are formed when a gelatin solution is cooled at a rate of 2°C/min to a temperature below the gel temperature. Microviscosity inside one kind of network is about four times lower than inside the other one. One with lower microviscosity is called a coarse network, and it is formed through aggregation of a collagen-like, triple-stranded helix. The other is named a fine network and it is constructed simply by entanglements between polymer chains. The structure of gelatin gel can be considered as a blend of these two networks. By controlling the cooling speed, the structure of gelatin gels can be dominated by either coarse or fine gel networks.Dedicated to Prof. Dr. W. Pechhold on the occasion of his 60th birthday.     

Synthesis of functionalized pyrimidine-4-thiones and derivatives of pyrido[2,3-d]pirimidine-5-one from monoacylketene aminals

Monoacylketene aminals containing an unsubstituted NH₂ group react as C-nucleophiles with benzoyl isothiocyanate to give the corresponding thioamides which undergo cyclization by sodium methoxide in methanol to afford 6-R-amino-5-acetyl-2-phenyl-3H-pyrimidine-4-thiones. A scheme for constructing the pyrido[2,3-d]pyrimidine system from keteneaminals is offered. The reaction of 6-R-amino-5-acetyl-2-phenyl-3H-pyrimidine-4-thiones with dimethylformamide dimethylacetal leads to 8-R-N-4-methylthio-8H-pyrido-[2,3-d]pyrimidine-5-ones. Cyclization of 5-acetyl-6-benzoylamino-4-methylthio-2-phenylpyrimidine by sodium methoxide yields N-unsubstituted 4-methylthio-8H-pyrido-[2,3-d]pyrimidine-5-one.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1932–1937, November, 1993     

增强型电荷耦合器件用于毛细管电泳激光诱导荧光的检测

增强型电荷耦合器件用于毛细管电泳激光诱导荧光的检测马明生，吴晓军，刘国诠（中国科学院化学研究所，北京，１０００８０）关键词增强型电荷耦合器件，激光诱导荧光，毛细管电泳，异硫氰酸荧光黄近年来，毛细管电泳技术在生化分离、分析中得到广泛的应用。目前，毛细管...     

Analytical potential of 6-oxy-(N-succinimidyl acetate)-9-(2'-methoxycarbonyl) fluorescein for the determination of amino compounds by capillary electrophoresis with laser-induced fluorescence detection

The analytical potential of a fluorescein analogue, 6-oxy-(N-succinimidyl acetate)-9-(2'-methoxycarbonyl) fluorescein (SAMF), for the first time synthesized in our laboratory, as a labeling reagent for the labeling and determination of amino compounds by capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection was investigated. Biogenic monoamines and amino acids were chosen as model analytes to evaluate the analytical possibilities of this approach. The derivatization conditions and separation parameters for the biogenic amines were optimized in detail. The derivatization was performed at 30 degrees C for 6 min in boric acid buffer (pH 8.0). The derivatives were baseline-separated in 15 min with 25 mM boric acid running buffer (pH 9.0), containing 24 mM SDS and 12.5% v/v acetonitrile. The concentration detection limit for biogenic amines reaches 8 x 10(-11) mol.L(-1) (signal-to-noise ratio = 3). The application of CE in the analysis of the SAMF-derivatized amino acids was also exploited. The optimal running buffer for amino acids suggested that weak acidic background electrolyte offered better separation than the basic one. The proposed method was applied to the determination of biogenic amines in three different beer samples with satisfying recoveries varying from 92.8% to 104.8%. Finally, comparison of several fluorescein-based probes for amino compounds was discussed. With good labeling reaction, excellent photostability, pH-independent fluorescence (pH 4-9), and the resultant widely suited running buffer pH, SAMF has a great prospect in the determination of amino compounds in CE.     

Synthesis of 4,5-dihydrothiazole derivatives by the reaction of perfluoro-2-methylpent-2-en-3-yl isothiocyanate with ambident N,O- and N,S-nucleophiles

The reactions of perfluoro-2-methylpent-2-en-3-yl isothiocyanate with ambident N,O- and N,S-nucleophiles (thiazole-2-thione, pyridine-2-thione, 2-hydroxypyridine, benzothiazole-2-thione, benzoxazole-2-thione, 3,4,5,6-tetrahydropyrimidine-2-thione) in the presence of triethylamine yield only 2-N-substituted 4,5-dihydrothiazole derivatives. The molecular structures of three products were determined by X-ray diffraction analysis. The reaction pathways are discussed.     

An Evaluation of Fluorometric Substrates for Lipase

Abstract

The results of a complete study of 12 substrates for lipase indicated 4-methyl umbelliferone heptanoate to be the best substrate for the analysis of this enzyme. Using this ester, from 0.000020 to 0.066 units per ml. of porcine pancreas lipase can be determined with an accuracy and precision of about 1.5%. Analysis is performed by a direct initial reaction rate method in 2–3 minutes.     

Trimethylsilyl isothiocyanate (TMSNCS): an efficient reagent for the one-pot synthesis of mercapto-1,2,4-triazoles

A mild, convenient, and efficient one-pot synthesis of mercapto-1,2,4-triazoles is described. Various hydrazides efficiently reacted with trimethylsilyl isothiocyanate (TMSNCS) under basic condition to give mercapto-1,2,4-triazoles in high yields.