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11.
12.
Sulfur-containing compounds in diesel have been speciated by comprehensive two-dimensional gas chromatography (GCxGC) with a sulfur chemiluminescence detector (SCD). The advantages of GCxGC technique are higher resolution and greater sensitivity. GCxGC-SCD can achieve the class separation of sulfur-containing compounds with an appropriate separation column combination. The major classes of sulfur-containing compounds in diesel are benzothiophenes and dibenzothiophenes. Relative concentration of each class as well as each carbon number family can be quantitated by the summation of the integrated areas corresponding to the individual group(s) in the GCxGC space. In practical applications, GCxGC-SCD can be used to characterize different diesels and to reflect desulfurization process efficiency. In this study, GCxGC-SCD has demonstrated its value in speciation of sulfur-containing compounds classes, which is difficult to accomplish by any other single technique. 相似文献
13.
Cycloadducts of hexafluorothioacetone (HFTA) were prepared in high yield by a CsF catalyzed reaction between readily available 2,2,4,4-tetrakis-(trifluoromethyl)-1,3-dithietane (as a source of HFTA) with conjugated electron-rich hydrocarbon dienes, such as cyclopentadiene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene or (1Z,3Z)-cyclohepta-1,3-diene. Cyclohexa-1,4- and (1Z,5Z)-cycloocta-1,5-dienes, also undergo the reaction with in situ generated HFTA, but form the products of insertion of HFTA into the C-H bond of the diene as a result of ene-reaction. The highly selective reaction of HFTA with (1Z,3Z,5Z)-cyclohepta-1,3,5-triene and (1Z,3Z,5Z,7Z)-cycloocta-1,3,5,7-tetraene leads to the formation of cycloadducts derived from exclusive addition of thioacetone to the corresponding bicyclic isomers—bicyclo[4.1.0]hepta-2,4-diene or bicyclo[4.2.0]octa-2,4,7-triene, respectively. The corresponding cycloadducts of HFTA with 2,3-dimethylbutadiene-1,3-cyclohexa-1,3-cyclohexa-1,4-dienes and (1Z,3Z,5Z)-cyclohepta-1,3,5-triene were also prepared by direct reaction of sulfur/hexafluoropropene/KF and the corresponding hydrocarbon substrate at 35-45 °C in DMF. 相似文献
14.
Inhaltsübersicht. Diphenylphosphin und rac-Cyclophosphamid (ClCH2CH2)2NP(O)N(H)(CH2)3O (1) reagieren in Gegenwart von n-Butyllithium zu einem Zwischenprodukt, das mit Wasser das diphenylphosphinsubstituierte Cyclophosphamid, (Ph2PCH2CH2)2NP(O)N(H)(CH2)3O, (2) bildet. Metallierung von 2 mit n-BuLi am N(3)-Atom und Umsetzung mit D2O führt zum N(3)-Deuteroderivat 2a. Mit H2O2 reagiert 2 zur all-Phosphinoxid Verbindung, [Ph2P(O)CH2CH2]2NP(O)N(H)(CH2)3O, (4), die mit 0,5 Mol Wasser auskristallisiert und von der zur Charakterisierung des H-Bückenbindungssystems eine Röntgenstrukturanalyse angefertigt wurde. Die NMR-Spektren (1H, 13C, 31P, 14N) weisen 2–4 als dynamische Moleküle aus. Chemistry of Polyfunctional Molecules. 101. Synthesis of a Diphenylphosphinesubstituted Cyclophosphamide and the X-ray Diffraction of its Oxidation Product Diphenylphosphine and rac-cyclophosphamide, (ClCH2CH2)2NP(O)N(H)(CH2)3O, (1) react in the presence of n-BuLi to an intermediate which hydrolyses to the diphenylphosphine substituted Cyclophosphamide, (Ph2PCH3CH2)2NP(O)N(H)(CH2)3O, (2). Metallation of 2 with n-BuLi at the N(3) atom, followed by treatment with D2O yields the N(3)-deuterated derivative 2a. With H2O2 2 forms the all-phosphine-oxide compound, [Ph2P(O)CH2CH2]2NP(O)N(H)(CH2)3O, ( 4 ), which crystallizes with 0.5 mole of water. In order to characterize the H-bridge bonding system a X-ray structure analysis of 4 was carried out. The NMR-Spectra (1H, 13C, 31P, 14N) indicate 2–4 as dynamic molecules. 相似文献
15.
L. G. Kostova W. Andrejtscheff L. K. Kostov L. Funke E. Will A. I. Vdovin 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(2):145-148
Using the (,n) reaction, the half-life of the first 11/2– level in97Mo has been determined as T1/2(1437.0 keV)=2.5±0.3 ns by means of the pulsed beam method. The experimentally obtainedB(M2) value between theh
11/2 andg
7/2 configurations in97Mo has been satisfactorily described within the quasiparticle-phonon model usingg
s
eff
=0.6g
s
free
. Similar calculations and comparisons with experminental data have been performed also for95,99Mo as well as for99Ru and101Pd.This work is partly supported by the Bulgarian National Research Foundation 相似文献
16.
Herein, we report the 1,2-dialkylation of simple feedstock acrylates for the synthesis of valuable tertiary carboxylic acids by merging Giese-type radical addition with an Ireland–Claisen rearrangement. Key to success is the utilization of the reductive radical-polar crossover concept under photocatalytic reaction conditions to force the [3,3]-sigmatropic rearrangement after alkyl radical addition to allyl acrylates. Using readily available alkyl boronic acids as radical progenitors, this redox-neutral, transition-metal-free protocol allows the mild formation of two C(sp3)–C(sp3) bonds, thus providing rapid access to complex tertiary carboxylic acids in a single step. Moreover, this strategy enables the efficient synthesis of highly attractive α,α-dialkylated γ-amino butyric acids (GABAs) when α-silyl amines are used as radical precursors – a structural motif that was still inaccessible in related transformations. Depending on the nature of the radical precursors and their inherent oxidation potentials, either a photoredox-induced radical chain or a solely photoredox mechanism is proposed to be operative.A photocatalytic 1,2-dialkylation of α-substituted acrylates is enabled by a reaction cascade combining reductive radical-polar crossover with the established Ireland–Claisen rearrangement for the synthesis of valuable tertiary carboxylic acids. 相似文献
17.
Dr. James Biggs Dr. Karsten Danielmeier Dr. Julia Hitzbleck Dr. Jens Krause Tom Kridl Dr. Stephan Nowak Dr. Enrico Orselli Dr. Xina Quan Dirk Schapeler Will Sutherland Dr. Joachim Wagner 《Angewandte Chemie (International ed. in English)》2013,52(36):9409-9421
We present the development and applications of dielectric elastomers. For the last 10 years the significance of this class of polymers has risen as more applications seem possible and first products have been commercialized. 相似文献
18.
We classify which complete multipartite graphs are intrinsically chiral. 相似文献
19.
Tucker McElroy 《Extremes》2016,19(3):467-490
The paper reviews the topic of extremal time series. The literature documenting the presence of extremes in time series data is first reviewed, followed by a discussion of various probabilistic measures, along with the associated statistical inference problems. The impact of extremes upon statistical analyses is discussed, and the connection to extremal latent components is emphasized. Two data sets illustrate the methods. 相似文献
20.