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141.
Production and Decomposition of (NH4)[BF4] and H3N‐BF3 (NH4)[BF4] is produced as single crystals during the reaction of elemental boron and NH4HF2 (B : NH4HF2 = 1 : 2) and NH4F (B : NH4F = 1 : 4), respectively, in sealed copper ampoules at 300 °C. The crystal structure (baryte type, orthorhombic, Pnma, Z = 4) was redetermined at ambient temperature (a = 909.73(18), b = 569.77(10), c = 729.47(11) pm, Rall = 0.0361) and at 140 K (a = 887.3(2), b = 574.59(12), c = 717.10(12) pm, Rall = 0.0321). Isolated (NH4)+ and [BF4]— tetrahedra are the important building units. The thermal behaviour of (NH4)[BF4] was investigated under inert (Ar, N2) and reactive conditions (NH3) with the aid of DTA/TG and DSC measurements and with in‐situ X‐ray powder diffraction as well. Finally, (NH4)[BF4] is decomposed yielding NH3 and BF3, BN is not produced under the current conditions. Colourless single crystals of H3N‐BF3 were prepared directly from the components NH3 and BF3. The crystal structure was determined anew at 293 and 170 K (orthorhombic, Pbca, Z = 8, a = 815.12(10), b = 805.91(14), c = 929.03(12) pm, Rall = 0.0367; a = 807.26(13), b = 800.48(10), c = 924.31(11) pm, Rall = 0.0292, T = 170 K). The crystal structure contains isolated molecules H3N‐BF3 in staggered conformation with a B‐N distance of 158 pm. The thermal behaviour of H3N‐BF3 was studied likewise. 相似文献
142.
Reaction of N-benzoyl-1,2,3,4-tetrahydroquinoline-2-carboxylic acid with acetic anhydride resulted in 1H,3H,5H-oxazolo[3,4-a]quinolin-3-one derivative 13. Different cyclopropanation processes were applied to 13, but only diazomethane in the presence of water furnished the hitherto unknown methyl 1,2,7,7a-tetrahydro-1aH-cyclopropa[b]quinoline-1a-carboxylate 14, which can be considered as a doubly constrained 1-aminocyclopropane-1-carboxylic acid system. The mechanism of the cyclopropanation was studied in detail. The new ACC ester 14 was transformed into fused tetracyclic hydantoin derivatives, which comprised a new type of heterocyclic system. 相似文献
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144.
Dirk Marsitzky Thorsten Brand Yves Geerts Markus Klapper Klaus Müllen 《Macromolecular rapid communications》1998,19(7):385-389
This paper describes a new way to synthesize rod-coil block copolymers consisting of poly(p-phenylene) (PPP) as rigid rod and either polystyrene (PS) or poly(ethylene oxide) (PEO) as flexible coil. The Suzuki-coupling of the AB-type monomer 4-bromo-2,5-diheptylbenzeneboronic acid (1) under strictly proton-free conditions leads to the control of PPP endgroups and hence allows the synthesis of a variety of differently end-functionalized poly(p-phenylene)s. The poly(2,5-diheptyl-p-phenylene)-block-polystyrene (7) is then prepared via condensation via condensation of anionically polymerized living polystyrene ( 6 ) with α-(4-formylphenyl)-ω-phenyl-poly(2,5diheptyl-p-phenylene) ( 4 ). Toluenesulfonic acid catalyzed condensation of α-methyl-ω-amino-poly(oxyethylene) ( 8 ) with PPP 4 yields poly(2,5-diheptyl-p-phenylene)-block-poly(ethylene oxide) ( 9 ). 相似文献
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147.
Binuclear Nickel(0) Alkyne Coordination Compounds – Correlation between Ligand Periphery and Supramolecular Structure Reaction of Ni(cdt: 1,5,9-cyclododecatriene) with functionalized alkynes and subsequent reaction with ethylenediamines gives binuclear compounds of the type (diamine)Ni(μ-alkyne)Ni(alkyne). Compounds with alkyne-diols (N?N)Ni2(HOR1R2C? C?C? CR1R2OH)2 show supramolecular structures in which two identical intramolecular and one intermolecular hydrogen bonds are realized. 1 and 2 (chelate ligand in each case N,N,N′,N′-tetramethylethylenediamine, TMEDA, in 1 R1 = R2 = Me, in 2 R1 = R2 = Et) polymer-like chains are built up by connecting the binuclear units. Via two intermolecular hydrogen bonds per organometallic unit in 1 and via one intermoleculare hydrogen bond in 2 the chains are connected to give double chains. By substitution of one methyl group of TMEDA by hydrogen ( 3 : R1 = R2 = Me) a polymerlike network is produced by connecting the polymer-like chains. In compound 4 in which one of the methyl groups of TMEDA is substituted by CH2CH2NMe2 the polymer-like chains remain unconnected. In 5 (diamine = TMEDA, alkyne = (CH3)3C? C?C? CMe2OH) one intermolecular hydrogen bond per organometallic unit is observed forming again polymer-like chains that are independent of each other. 相似文献
148.
Klaassen T Kasel D Harlfinger S Fuhr U 《Rapid communications in mass spectrometry : RCM》2004,18(15):1675-1680
A reliable and easy to use liquid chromatography/tandem mass spectrometry (LC/MS/MS) method without the use of sample extraction was developed for the simultaneous quantification of urinary concentrations of mephenytoin, a standard phenotyping substrate for the cytochrome P450 enzyme CYP2C19, and its phase I metabolites 4'-hydroxymephenytoin and nirvanol. Fifty microL of urine were diluted with a buffered beta-glucuronidase solution and incubated at 37 degrees C for 6 h followed by addition of methanol, containing the internal standard 4'-methoxymephenytoin. The chromatographic separation was achieved using a 100 x 3 mm, 5 micro Thermo Electron Aquasil C18 column with a gradient flow, increasing the organic fraction (acetonitrile/methanol 50:50) of the mobile phase from 10 to 90%. Quantification by triple-stage mass spectrometry (TSQ Quantum, Thermo Electron) was accomplished by negative electrospray ionization in the selected reaction monitoring mode. Linearity was observed for all substances in the concentration range 15-10 000 ng/mL. The lower limit of quantification (LLOQ) was 20 ng/mL for 4'-hydroxymephenytoin and 30 ng/mL for nirvanol and mephenytoin, respectively. Intra- and inter-day inaccuracy did not exceed 9.5% for all substances from LLOQ to 10 000 ng/mL. Intra- and inter-day precision were in the range of 0.8-10.5%. The method was validated according to international ICH and FDA guidelines and successfully applied for phenotyping of Caucasian male volunteers who received an oral dose of 50 mg mephenytoin. 相似文献
149.
Christian K. Frese Dirk Nolting A. F. Maarten Altelaar Jens Griep-Raming Shabaz Mohammed Albert J. R. Heck 《Journal of the American Society for Mass Spectrometry》2013,24(11):1663-1670
Electron transfer dissociation (ETD) is commonly employed in ion traps utilizing rf fields that facilitate efficient electron transfer reactions. Here, we explore performing ETD in the HCD collision cell on an Orbitrap Velos instrument by applying a static DC gradient axially to the rods. This gradient enables simultaneous three dimensional, charge sign independent, trapping of cations and anions, initiating electron transfer reactions in the center of the HCD cell where oppositely charged ions clouds overlap. Here, we evaluate this mode of operation for a number of tryptic peptide populations and the top-down sequence analysis of ubiquitin. Our preliminary data show that performing ETD in the HCD cell provides similar fragmentation as ion trap-ETD but requires further optimization to match performance of ion trap-ETD. 相似文献