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31.
32.
Organocatalytic enantioselective Friedel-Crafts reaction of pyrrole derivatives with imines 总被引:2,自引:0,他引:2
A highly enantioselective Friedel-Crafts reaction of pyrrole derivatives with N-acyl imines catalyzed by chiral phosphoric acids was developed. The reactions produced the pyrrole derivatives in high yields and enantioselectivity. 相似文献
33.
Smith BE Sutton PA Lewis CA Dunsmore B Fowler G Krane J Lutnaes BF Brandal Ø Sjöblom J Rowland SJ 《Journal of separation science》2007,30(3):375-380
Examination by high temperature GC (HTGC) of the methyl esters of the so-called 'ARN' naphthenic acids from crude oils of North Sea UK, Norwegian Sea and West African oilfields revealed the distributions of resolved 4-8 ring C80 tetra acids and trace amounts of other acids. Whilst all three oils contained apparently the same major acids, the proportions of each differed, possibly reflecting the growth temperatures of the archaebacteria from which the acids are assumed to have originated. The structures of the 4, 5, 7 and 8 ring acids are tentatively assigned by comparison with the known 6 ring acid and related natural products and an HPLC method for the isolation of the individual acids is described. ESI-MS of individual acids isolated by preparative HPLC established the elution order of the 4-8 ring acids on the HPLC and HTGC systems and revealed the presence of previously unreported acids tentatively identified as C81 and C82 7 and 8 ring analogues. 相似文献
34.
35.
EA Appel MJ Rowland XJ Loh RM Heywood C Watts OA Scherman 《Chemical communications (Cambridge, England)》2012,48(79):9843-9845
Temozolomide (TMZ) is the primary chemotherapeutic agent for treatment of glioblastoma multiforme (GBM) yet it has a fast rate of degradation under physiological conditions to the 'active' MTIC, which has poor penetration of the blood-brain barrier and cellular absorption. Herein we have demonstrated binding of TMZ within the cavity of nano-container cucurbit[7]uril, resulting in a decreased rate of drug degradation. Prolonging the lifetime of the TMZ under physiological conditions through encapsulation dramatically improved the drug's activity against primary GBM cell lines as more TMZ could be absorbed by the cells before degradation. This work can potentially lead to increases in the drug's propensity for crossing the blood-brain barrier and absorption into the GBM cells, thereby increasing the efficacy of this chemotherapy. 相似文献
36.
Pulsed laser photolysis, time-resolved laser-induced fluorescence experiments have been carried out on the reactions of CN radicals with CH4, C2H6, C2H4, C3H6, and C2H2. They have yielded rate constants for these five reactions at temperatures between 295 and 700 K. The data for the reactions with methane and ethane have been combined with other recent results and fitted to modified Arrhenius expressions, k(T) = A′(298) (T/298)n exp(?θ/T), yielding: for CH4, A′(298) = 7.0 × 10?13 cm3 molecule?1 s?1, n = 2.3, and θ = ?16 K; and for C2H6, A′(298) = 5.6 × 10?12 cm3 molecule?1 s?1, n = 1.8, and θ = ?500 K. The rate constants for the reactions with C2H4, C3H6, and C2H2 all decrease monotonically with temperature and have been fitted to expressions of the form, k(T) = k(298) (T/298)n with k(298) = 2.5 × 10?10 cm3 molecule?1 s?1, n = ?0.24 for CN + C2H4; k(298) = 3.4 × 10?10 cm3 molecule?1 s?1, n = ?0.19 for CN + C3H6; and k(298) = 2.9 × 10?10 cm3 molecule?1 s?1, n = ?0.53 for CN + C2H2. These reactions almost certainly proceed via addition-elimination yielding an unsaturated cyanide and an H-atom. Our kinetic results for reactions of CN are compared with those for reactions of the same hydrocarbons with other simple free radical species. © John Wiley & Sons, Inc. 相似文献
37.
This paper outlines the application of electronic speckle pattern interferometry (ESPI) to the measurement of dynamic bulk modulus of elastomers. This is achieved by direct measurement of the volume contraction of submerged specimens subjected to sinusoidal pressure changes. Also outlined is the stroboscopic operation of ESPI for the identification of phase delays between peak loading and maximum deformation, characteristic of the response of viscoelastic materials. 相似文献
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39.
R. A. Alvarez A. D. Dougan M. R. Rowland T. F. Wang 《Journal of Radioanalytical and Nuclear Chemistry》1995,192(1):73-80
A non-destructive analysis technique using a protable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The braod range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should lead to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers.Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. 相似文献
40.
Stanley P. Rowland Earl J. Roberts Alfred D. French 《Journal of polymer science. Part A, Polymer chemistry》1974,12(2):445-454
The relative availabilities of hydroxyl groups at C(2), C(3), and C(6) on the D -glucopyranosyl units of a particular, highly ordered hydrocellulose II have been studied by means of the reaction of N,N-diethylaziridinium chloride, which introduces 2-(diethyl-amino)ethyl substituents. The hydrocellulose II was formed by hydrolysis of fibrous cotton cellulose II during 40 min reflux in 2.5M hydrochloric acid and is designated EHC-II (exemplar hydrocellulose II) because it represents the most highly ordered (crystalline) particles in a series of hydrocelluloses. The deviation in the distribution of substituents among the 2-O-, 3-O-, and 6-O- positions of the D -glucopyranosyl units in EHC-II from that in a disordered cellulose, in which the three types of hydroxyl groups are equally available, is the basis for estimated availabilities of the three types of hydroxyl groups on the surfaces of elementary fibrils in EHC-II. The experimental values of relative availabilities of O(2)H:O(3)H:O(6)H for EHC-II were 1.0:0.26:0.72 compared to estimated values of 1.0:0.0:.075 for surfaces of elementary fibrils of an idealized, perfectly ordered cellulose II, a model that is based on intensities of x-ray diffraction peaks. 相似文献