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81.
Heterolysis of H2 Across a Classical Lewis Pair, 2,6‐Lutidine⋅BCl3: Synthesis,Characterization, and Mechanism 下载免费PDF全文
Bojana Ginovska Dr. Tom Autrey Dr. Kshitij Parab Dr. Mark E. Bowden Dr. Robert G. Potter Dr. Donald M. Camaioni 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15713-15719
We report that 2,6‐lutidine?trichloroborane (Lut?BCl3) reacts with H2 in toluene, bromobenzene, dichloromethane, and Lut solvents producing the neutral hydride, Lut?BHCl2. The mechanism was modeled with density functional theory, and energies of stationary states were calculated at the G3(MP2)B3 level of theory. Lut?BCl3 was calculated to react with H2 and form the ion pair, [LutH+][HBCl3?], with a barrier of ΔH≠=24.7 kcal mol?1 (ΔG≠=29.8 kcal mol?1). Metathesis with a second molecule of Lut?BCl3 produced Lut?BHCl2 and [LutH+][BCl4?]. The overall reaction is exothermic by 6.0 kcal mol?1 (ΔrG°=?1.1). Alternate pathways were explored involving the borenium cation (LutBCl2+) and the four‐membered boracycle [(CH2{NC5H3Me})BCl2]. Barriers for addition of H2 across the Lut/LutBCl2+ pair and the boracycle B?C bond are substantially higher (ΔG≠=42.1 and 49.4 kcal mol?1, respectively), such that these pathways are excluded. The barrier for addition of H2 to the boracycle B?N bond is comparable (ΔH≠=28.5 and ΔG≠=32 kcal mol?1). Conversion of the intermediate 2‐(BHCl2CH2)‐6‐Me(C5H3NH) to Lut?BHCl2 may occur by intermolecular steps involving proton/hydride transfers to Lut/BCl3. Intramolecular protodeboronation, which could form Lut?BHCl2 directly, is prohibited by a high barrier (ΔH≠=52, ΔG≠=51 kcal mol?1). 相似文献
82.
Identification of homemade inorganic explosives by ion chromatographic analysis of post-blast residues 总被引:1,自引:0,他引:1
Johns C Shellie RA Potter OG O'Reilly JW Hutchinson JP Guijt RM Breadmore MC Hilder EF Dicinoski GW Haddad PR 《Journal of chromatography. A》2008,1182(2):205-214
Anions and cations of interest for the post-blast identification of homemade inorganic explosives were separated and detected by ion chromatographic (IC) methods. The ionic analytes used for identification of explosives in this study comprised 18 anions (acetate, benzoate, bromate, carbonate, chlorate, chloride, chlorite, chromate, cyanate, fluoride, formate, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate and thiosulfate) and 12 cations (ammonium, barium(II), calcium(II), chromium(III), ethylammonium, magnesium(II), manganese(II), methylammonium, potassium(I), sodium(I), strontium(II), and zinc(II)). Two IC separations are presented, using suppressed IC on a Dionex AS20 column with potassium hydroxide as eluent for anions, and non-suppressed IC for cations using a Dionex SCS 1 column with oxalic acid/acetonitrile as eluent. Conductivity detection was used in both cases. Detection limits for anions were in the range 2-27.4ppb, and for cations were in the range 13-115ppb. These methods allowed the explosive residue ions to be identified and separated from background ions likely to be present in the environment. Linearity (over a calibration range of 0.05-50ppm) was evaluated for both methods, with r(2) values ranging from 0.9889 to 1.000. Reproducibility over 10 consecutive injections of a 5ppm standard ranged from 0.01 to 0.22% relative standard deviation (RSD) for retention time and 0.29 to 2.16%RSD for peak area. The anion and cation separations were performed simultaneously by using two Dionex ICS-2000 chromatographs served by a single autoinjector. The efficacy of the developed methods was demonstrated by analysis of residue samples taken from witness plates and soils collected following the controlled detonation of a series of different inorganic homemade explosives. The results obtained were also confirmed by parallel analysis of the same samples by capillary electrophoresis (CE) with excellent agreement being obtained. 相似文献
83.
Takayoshi Tsuzuki Natsumi Sakaguchi Dr. Takashi Kudoh Satoshi Takano Masato Uehara Dr. Takashi Murayama Prof. Dr. Takashi Sakurai Dr. Minako Hashii Prof. Dr. Haruhiro Higashida Karin Weber Prof. Dr. Andreas H. Guse Dr. Tomoshi Kameda Dr. Takatsugu Hirokawa Dr. Yasuhiro Kumaki Prof. Dr. Barry V. L. Potter Dr. Hayato Fukuda Dr. Mitsuhiro Arisawa Prof. Dr. Satoshi Shuto 《Angewandte Chemie (International ed. in English)》2013,52(26):6633-6637
84.
J. H. Ross A. C. Hill L. E. Wise A. M. Fairbrother W. M. Harlow J. C. Potter A. Noll und H. Schwalbe 《Fresenius' Journal of Analytical Chemistry》1933,92(3-4):154-157
Ohne Zusammenfassung 相似文献
85.
Novel macroporous monolithic stationary phase materials suitable for microscale boronate affinity chromatography were developed. 相似文献
86.
We compute ab initio cross sections for cold collisions of Rb atoms with OH radicals. We predict collision rate constants of order 10(-11) cm3/s at temperatures in the range 10-100 mK at which molecules have already been produced. However, we also find that in these collisions the molecules have a strong propensity for changing their internal state, which could make sympathetic cooling of OH in a Rb buffer gas problematic in magnetostatic or electrostatic traps. 相似文献
87.
Fang YQ Bio MM Hansen KB Potter MS Clausen A 《Journal of the American Chemical Society》2010,132(44):15525-15527
A general inversion-stereospecific, N-selective alkylation of substituted 2-pyridones (and analogues), amides, and carbamates using chiral α-chloro- or bromocarboxylic acids in the presence of KOt-Bu (or KHMDS) and Mg(Ot-Bu)(2) is reported. The resulting α-chiral carboxylic acid products were isolated by crystallization in good chemical yields and in high ee (>90% ee). Mechanistic evidence suggests that the reaction proceeds through 2-pyridone O-coordinated Mg carboxylate intermediates, which afford the product through an intramolecular S(N)2 alkylation. 相似文献
88.
Ciarán F. Potter Noel R. Russell Mary McNamara 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(3-4):395-403
The derivatives 6-Deoxy-6-[1-(2-amino)ethylamino]-β-Cyclodextrin (CDEn), 6-Deoxy-6-[1-(3-amino)propylamino]-β-Cyclodextrin
(CDPn) and 6-Deoxy-6-[1-(4-amino)butylamino]-β-Cyclodextrin (CDBn) were assessed with a view to demonstrating that increasing
the chain length of the diaminoalkane moiety can affect the chiral selectivity of the metallo-complexes of these materials.
It was shown that IR and Raman spectroscopies can be used to characterise these compounds. The results obtained from the electronic
absorption spectra suggested the formation of CuCDAm binary complexes and that the derivatives CDEn and CDPn act as bidentate
ligands while CDBn acts as a monodentate ligand due to its longer alkane chain. This study also showed that in the ternary
complexes with DOPA there is further coordination of the metal ion to the amino nitrogen atom and the hydroxyl oxygen atom
of the drug. On the basis of the results of the circular dichroic spectroscopic studies it was suggested that CuCDEn is the
better enantioselective material for DOPA and it acts in a multi-site recognition manner, utilising the inclusion properties
of the CD cavity in cooperation with the coordination properties of the metal ion. 相似文献
89.
Summary A simple and rapid method for the determination of organophosphorus insecticides in serum of poisoned patients is described.
The compounds are extracted with benzene and the extraction residue is gas chromatographed on a glass capillary column with
alkali flame ionisation detection. Concentrations from 2 ng cm−3 can be determined. As an example, results of the analysis of serum samples of three patients, poisoned with parathion and
methylparation, are given. 相似文献
90.
N. G. Semaltianos S. Logothetidis W. Perrie S. Romani R. J. Potter M. Sharp P. French G. Dearden K. G. Watkins 《Applied Physics A: Materials Science & Processing》2009,94(3):641-647
Nanoparticles of the II–VI semiconductors CdTe, CdSe and ZnTe were synthesized by laser ablation (387 nm, 180 fs, 1 kHz, pulse
energy of 7 μJ (fluence of 2 J/cm2)) of the target materials in methanol, de-ionized water and acetone. The nanoparticles size distributions follow log-normal
functions with median diameters between about 6 and 11 nm for the several materials. The nanoparticles have the same crystalline
structure as that of the corresponding bulk material and under the present conditions of ablation are rich in the higher volatility
element of the two in the binary alloy and oxidized. Photoluminescence emission in the green-yellow (∼570 nm) was detected
from CdSe nanoparticles. 相似文献