Effect of 2,2,6,6-tetramethyl-1-piperidinyloxy nitroxide substituent on kinetic parameters of pseudoliving polymerization

The main kinetic and thermodynamic parameters of the pseudoliving radical polymerization of styrene mediated by 4-linoleamido-2,2,6,6-tetramethyl-1-piperidinyloxy have been studied. It has been shown that the introduction of the said substituent into nitroxide leads to a marked reduction in the rate constant of reinitiation that is compensated for by the simultaneous reduction in the rate constant of reversible termination. As a result, the rate of pseudoliving polymerization, the rate of molecular mass growth, and the polydispersity of the polymer appear to be practically the same for processes mediated by both unsubstituted and substituted nitroxides.     

Cyclocondensation of [1-Cyano-2-(methylsulfanyl)vinyl]triphenylphosphonium Iodide with Amidine Nucleophiles

The substituted vinylphosphonium salt (E)-MeSCH=C(CN)P⁺Ph₃I⁻ readily cyclizes under the action of benzamidine and 3-amino-s-triazole, but it does not enter cyclocondensation with 2-aminopyridine. The structure of the cyclization product with 3-amino-s-triazole was confirmed by its transformation to 7-imino-6-(triphenylphosphoranylidene)-6,7-dihydro-s-triazolo[1,5]pyrimidine which was identified by X-ray diffraction. This stabilized ylide and its analogs proved useful starting materials for regioselective syntheses of 2-R-4-alkyl-4,7-dihydro-s-triazolo[1,5-a]pyrimidin-7-ones.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 565–570.Original Russian Text Copyright © 2005 by Smolii, Muzychka, Chernega, Drach.     

Cyanoacetylene and Its Derivatives: XXXIV. Nucleophilic Addition of Tetrazole to Cyanoacetylenes

Nucleophilic addition of tetrazole to 4-hydroxy-4-alkyl-2-alkynonitriles and to 3-phenyl-2-propynonitrile occurred regiospecifically and afforded E-, Z-4-hydroxy-4-methyl-3-tetrazolyl-2-alkenonitriles and 3-tetrazolyl-3-phenyl-2-propenonitrile [20–40°C, 13–50 h, 4–15 wt% MOH (M = Na, K), THF (or DMSO)] in up to 69% yield. The attempt to perform cyclization of the hydroxy-containing adducts into iminodihydrofurans (KOH, ethanol, 23-25°C) resulted in vinyl nucleophilic substitution of the tetrazole moiety by an ethoxy group.     

Berberis alkaloids. XXI. Intebrine — A new N-benzylisoquinoline alkaloid from Berberis integerrima

A new N-benzylisoquinoline alkaloid — intebrine, with the composition C₂₀H₁₉NO₇ — has been isolated fromBerberis integerrima Bunge. The spatial structure of intebrine has been reliably determined by the x-ray structural method (diffractometer, CuK radiation, 972 reflections, direct method, R=0.048). Its chemical behavior, spectral characteristics, and mass-spectrometric fragmentation under electrom impact have been studied.Andizhan State Medical Institute. Institute of the Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedeninii, No. 1, pp. 65–70, January–February, 1993.     

On heavy-atom blocking of intramolecular vibrational energy transfer in the 4-(trimethyl tin)butyl-2 radical

The 4-(trimethyl tin)butyl-2 radical, prepared and excited by the chemical activation reaction of H atoms with 4-(trimethyl tin)butene-1, was found to randomize its excess internal vibrational energy on a subpicosecond time scale. This result differs from an earlier study on the decomposition of 3-(triallyl tin)-2-fluoropropyl radical in which heavy-atom blocking of internal relaxation was reported.     

Quantitative Bestimmung von Sulfat und Sulfid (nach Oxydation) mit Hilfe des Orion-„Ionalizers“

A potentiometric procedure for the determination of sulphate has been tested. The analysis requires approx. 10–15 min time. The determination of the end-point is free from individual influences. In the determination of 0.1 N sodium sulphate an average error of the single measurement of fm=± 0.7% was observed. The more detailed complexometric method according to ?Deutsche Einheitsverfahren“ yielded an average mistake of fm=±2%. The method was applied to the determination of sulphate from sulphide (after oxidation of the latter). No considerable deviation from the gravimetrically ascertained values was noted. Borate does not interfere.     

Homolytic reactions of polyfluoroaromatic compounds V. The reaction of pentafluorophenyl radicals with fluorobenzene

The arylation of fluorobenzene with pentafluorophenyl radicals obtained by the reaction of the corresponding aniline with pentyl nitrite is described. The reaction involves attact at the 2t?-,3t?-and 4t?-positions. The composition of the mixture and the nature of its components were determined by ¹⁹F NMR spectroscopy and were confirmed by gas-liquid chromatography.     

Schwingungsspektren und Normalkoordinatenanalyse einiger Methyl-und Trimethylsilyl-hydroxylamine

Zusammenfassung Die Infrarot-und Raman-Spektren folgender Hydroxylamin-Derivate wurden registriert und zugeordnet: (CH₃)₃SiONH₂ (1), (CH₃)₃SiONHSi(CH₃)₃, (CH₃)₃SiON[Si(CH₃)₃]₂ (3), CH₃ONH₂ (4), CH₃ON[Si(CH₃)₃]₂ (5), CH₃NHOCH₃, CH₃N[Si(CH₃)₃]OCH₃, (C₂H₅)₂NOH und (C₂H₅)₂NOSi(CH₃)₃. Eine Normalkoordinatenanalyse für NH₂OH,1, 3, 4 und5 zeigt, daß sich die Spektren durch Übertragung gleichbleibender Kraftkonstanten der Molekülfragmente wiedergeben lassen. O-und N-Substituenten beeinflussen die NO-Kraftkonstante nicht; die SiO-und SiN-Valenzkraftkonstanten sind mit 3,3 mdyn/Å bemerkenswert niedrig.

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Vibrational spectra and normal coordinate analysis of some methyl-and trimethylsilylhydroxylamines

The infrared and Raman spectra of the hydroxylamine derivatives quoted above were recorded and frequencies assigned. A normal coordinate treatment of NH₂OH,1, 3, 4 and5 showed that the spectra can be explained by a single force field set up by transferring force constants from the different fragments of the molecules. The NO stretching force constant remains unaffected by different substituents. The SiO and SiN stretching force constants are remarkably small (c. 3.3 mdyn/Å).

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Mit 4 Abbildungen     

Influences of surface chemistry on the separation behavior of stationary phases for reversed-phase and ion-exchange chromatography: a comparison of coated and grafted supports prepared by ring-opening metathesis polymerization

A series of poly(norborn-2-ene) (poly-NBE), poly(7-oxanorborne-2-ene-5,6-dicarboxylic acid) (poly-ONDCA), as well as poly(norborn-2-ene-co-7-oxanorborne-2-ene-5,6-dicarboxylic acid) (poly-NBE-co-ONDCA) based silica supports were prepared via ring-opening metathesis polymerization (ROMP) using both coating and grafting techniques. Poly-NBE-grafted and poly-NBE-coated supports were used for the reversed-phase separation of phenols; poly-NBE, poly-ONDCA as well as poly-NBE-co-ONDCA-grafted supports were used for comparative studies on the separation of a series of anilines and lutidines. As expected, grafted supports possess superior separation capabilities compared to their coated analogues. Compared to pure poly-NBE- and poly-ONDCA-grafted stationary phases, supports consisting of poly-NBE-co-ONDCA block-copolymers possess both hydrophobic and ion-exchange sites and represent optimum stationary phases for the separation of isomeric basic analytes.     

Molekülsruktur und abs. konfiguration von (+)-p-menthadien-(1,8)-on-(2)-rhodium(I)-h5-cyclopentadienid, (+)-(4S-Carvon) RhI(C5H5)

The title compound crystallizes in the orthorhombic space group P2₁2₁2₁ with 4 molecules in the unit cell (cell dimensions: a 9.778(2), b 10.639(2) and c 12.423(4) Å). The structure was solved by means of the heavy atom method. The rhodium atom is linked to both olefinic double bonds. The terpene carbonyl group does not participate in coordination to rhodium. Unlike the endocyclic olefinic group, which is approximately perpendicular to the coordination plane of rhodium, the exocyclic Cz.sbnd;C double bound shows a considerable deviation from this arrangement. The π-complexation of carvone with rhodium proceeds diastereospecifically. The absolute configuration of (+)-carvone is 4S in agreement with the assignment derived by indirect chemical correlation.