Phytoecdysteroids of plants of the genusSilene XIV. Brahuisterone fromSilene brahuica

A new ecdysteroid with the composition C₂₇H₄₄O₆ which has been called brahuisterone has been isolated from the epigeal part of the plantSilene brahuica Boiss. Its chemical and complete spatial structures have been established by spectral studies and the x-ray structural method (diffractometer, Cu-K radiations, 996 reflections, direct method, R=0.119).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbekistan Republic, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 553–558, July–August, 1993.     

Electrophilic addition of lead tetraacetate to 2-carene in an acidic medium

Oxidation of 2-carene by lead tetraacetate in acetic acid afforded p-menth-1(10),2-dien-7-ol, 2-acetyl-6,6-dimethylbicyclo[3.1.0]hexane, p-menth-2-ene-1,7-diol, p-menth-1-ene-3,7-diol, and 2-(m-tolyl)propanol-2.Deceased.A. M. Butlerov Scientific Research Chemical Institute, V. I. Ul'yanov-Lenin Kazan' State University, 420008 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 147–150, January, 1992.     

Synthesis and properties of benzyl-substituted thiiranes

The reaction of phenyl- and p-tolylmagnesium bromides, as well as di, tri, and tetramethylbenzene, with epichlorohydrin was used to synthesize the corresponding chlorohydrins, which were then converted to various benzyl-substituted oxiranes and thiiranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 598–602, May, 1988.     

Polargraphic adsorptive waves of alkaline-earth metal complexes with thymolphthalexone

Sensitive derivative polarographic adsorption waves have been observed for alkaline-earth metal-TP complexes in 0.15M potassium hydroxide containing 3 x 10(-5)M thymolphthalexone (TP). The limit of detection for calcium, strontium and barium was 7.5 x 10(-7)M and for magnesium 4.0 x 10(-6)M. The proposed method has been used successfully for determining trace amounts of calcium in natural waters and hair samples. The composition of the complex has been shown to be 1:1 alkaline-earth metal:TP and various experiments have confirmed that the wave is an adsorption wave. The reaction mechanism has been studied by a number of methods.     

Synthesis and stereochemical studies of 6-substituted 1H,3H,6H,7aH-3,3-dimethylimidazo-[1,5-c]thiazol-5-one-7-thiones

The reaction of (4S)-5,5-dimethyl-4-thiazolidine-carboxylic acid 1 with alkyl and aryl isothiocyanates 2 gave bicyclic thiohydantoins 3 . The (2R,4S)- and (2S,4S)-mixtures of 2-substituted 5,5-dimethyl-4-thiazolidine-carboxylic acids 4 and 8 containing two centers of chirality in the analogous reaction afforded thiohydantoins 7 and 10 , respectively, with (1R)-configuration. In some cases we managed to isolate the thioureido acid intermediates 6 and 9 or their triethylamine salts which afforded the corresponding bicycles 7 and 10 under thermal cyclization or acidification. The stereochemistry has been elucidated by high resolution ram studies, optical rotation measurements and X-ray crystallography.     

Studies of the structural peculiarities and chemical changes of carbazole and of some of its derivatives

Oxidation of the corresponding 3, 6-diacetylcarbazoles gives 9-n-butyl- and 9-isoamylcarbazole-3, 6-dicarboxylic acids. 9-Alkylcarbazole-3, 6-dicarboxylic acids are converted to acid chlorides, which are esterified with allyl alcohol without being isolated pure. Allyl 9-ethyl-, 9-n-butyl- and 9-isoamylcarbazole-3, 6-dicarboxylates are synthesized. The ability of these esters to polymerize and to undergo copolymerization with methyl mercaptan is demonstrated with the example of diallyl 9-ethylcarbazole-3, 6-dicarboxylate.For Part XII see [8].     

Analysis of plutonium in biological and environmental materials

A procedure for separation of plutonium from some biological and environmental materials has been tested in model and real conditions. The procedure involves a commonly used way of conversion of plutonium to oxidation state (IV) in nitric acid medium and sorption of Pu(IV) on a strongly basic anion exchanger from hydrochloric acid medium thus eliminating interference of²²⁸Th with the²³⁸Pu analysis.     

Rapid radiochemical neutron activation analysis for iodine in urine by different separation techniques.

In the present work on radiochemical neutron activation analysis for the determination of iodine in urine samples, the performance of three different radiochemical separation techniques, namely, direct extraction, use of an iodinated ion-exchange resin column and Sch?niger combustion, were intercompared and validated. The practical advantages of the iodinated-resin technique make it most suitable for the rapid routine determination of iodine in urine. It was further verified by participation in an international intercomparison run of urine analysis, and used in a pilot study on iodine determination in the urine of 171 Slovenian schoolchildren, where it gave results in good agreement with the catalytic method.     

In situ sensing of the middle atmosphere with balloonborne near-infrared laser diodes

Since 1997, two near-infrared laser diode sensors have been developed with the support of the CNES, the French space agency, to provide in situ data of H(2)O, CH(4) and CO(2) in the middle atmosphere. The realized instruments were flown from stratospheric balloons within the framework of European campaigns for the study of stratospheric ozone and water vapor and were involved in the validation of the ODIN and ENVISAT satellites. In this paper, we describe the developed laser probing technique, we report atmospheric measurements and finally we discuss future perspectives, particularly the in situ laser sensing of the lower atmosphere of Mars and the implication of the laser hygrometers in balloon campaigns at mid-latitudes and tropical regions to investigate the sources and sinks of stratospheric H(2)O.     

Determination of manganese in grain by potential titration with catalytic end-point indication

A method of catalytic potential titration for the determination of trace manganese by using crystal violet ion selective electrode is reported in this paper. It is based on the catalytic effect of manganese (II) on the oxidation of crystal violet by potassium periodate in the presence of nitrilotriacetic acid (NTA). The experiments indicated that this technique showed high sensitivity and high accuracy. The results of determination of trace manganese in grain could be compared with the results obtained by means of atomic absorption spectrometry.