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101.
Judit Tulla-Puche 《Tetrahedron》2005,61(8):2195-2201
Sonogashira chemistry can be used according to the ‘resin-to-resin transfer reaction’ (RRTR) concept. Two fragments, one containing the halide moiety and the second one incorporating the alkyne functionality, are anchored on different solid supports using allyl and/or Wang-type linkages. Treatment with Pd(0) cleaves the allyl-linked fragment(s) which subsequently undergo Sonogashira coupling under the same conditions. 相似文献
102.
Rudnev AV Aleksenko SS Semenova O Hartinger CG Timerbaev AR Keppler BK 《Journal of separation science》2005,28(2):121-127
A CE method has been developed to evidence and quantitatively characterize the interaction between platinum-based antitumor drugs and human serum proteins. This method is a variant of affinity CE modified regarding both experimental setup and data treatment so as to measure the peaks (or vacancies) that correspond to the bound drug when it slowly binds to the protein. Using the formalism of the Hummel-Dreyer method and cisplatin and oxaliplatin as test compounds, a protocol for determining albumin and transferrin binding constants and stoichiometries, including (and distinguished by) 48 hours of incubation of the reaction mixture, was elaborated. Relative affinities of drugs toward different proteins in aqueous solution at physiological pH, chloride concentration, and temperature were compared in terms of overall binding constants and numbers of drug molecules attached to the protein. The results indicate that both platinum drugs bind to albumin more strongly than to transferrin, supporting the concept that the albumin fraction is a major drug supply route for chemotherapeutical needs. From a comparison with the binding parameters measured previously for cisplatin by other methods, conclusions were drawn about the validity of CE as a simple and convenient method for assaying protein-drug reactions with slow kinetics. 相似文献
103.
Benzoxazine-bismaleimide blends: Curing and thermal properties 总被引:4,自引:0,他引:4
A blend of bisphenol A based benzoxazine (Bz-A) and a bismaleimide (2,2-bis[4(4-maleimidophenoxy) phenyl] propane (BMI), was thermally polymerised in varying proportions and their cure and thermal characteristics were investigated. The differential scanning calorimetric analysis, supplemented by rheology confirmed a lowering of the cure temperature of BMI in the blend implying catalysis of the maleimide polymerisation by benzoxazine. FTIR studies provided evidences for the H-bonding between carbonyl group of BMI and -OH group of polybenzoxazine in the cured matrix. The cured matrix manifested a dual phase behaviour in SEM and DMTA with the minor phase constituted by polybenzoxazine dispersed in an interpenetrating polymer network (IPN) of polybenzoxazine and cured BMI. The IPN possessed improved thermal stability over the constituent polybenzoxazine. A benzoxazine monomer possessing allyl functional groups, 2,2′-bis(8-allyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl) propane (Bz-allyl) was reactively blended with the same bismaleimide in varying stoichiometric ratios (Bz-allyl/BMI), where the curing involved mainly Alder-ene reaction between allyl- and maleimides groups and ring-opening polymerisation of benzoxazine. The rheological analysis showed the absence of catalytic polymerisation of BMI in this case. The overall processing temperature was lowered in the blend owing to the co-reaction of the two systems to form a single-phase matrix. The cured resins of both Bz-A/BMI and Bz-allyl/BMI blends exhibited better thermal stability than the respective polybenzoxazines. The Tg of the IPN was significantly improved over that of polybenzoxazine (Bz-A). However, the co-reaction resulted in a marginal decrease in the Tg of the system in comparison to the polybenzoxazine (Bz-allyl). 相似文献
104.
A simple and efficient one-step, regioselective, enzymatic glucosylation of arbutin by α-glucosidase
4-Hydroxyphenyl-β-isomaltoside has been synthesized by α-glucosidase assisted transglycosylation between arbutin as acceptor and sucrose as donor molecules, respectively. Optimum conditions for the transglucosylation reaction were 40 °C for 20 h with 10 mM arbutin and 1.5 M sucrose in a 100 mM sodium citrate/phosphate buffer at pH 5.0. The new glucoside was obtained in a 50% molar yield with respect to arbutin. 相似文献
105.
Mariappan PeriasamyN. KishoreBabu Keela Natarajan Jayakumar 《Tetrahedron letters》2003,44(50):8939-8941
The reactions of arylacetic acid esters with tertiary arylamines in the presence of TiCl4 give α-arylated products in 65-90% yields, as well as 10-20% yields of the corresponding benzidines. 相似文献
106.
Núñez Lisardo Fraga L. Núñez M. R. Villanueva M. Rial B. 《Journal of Thermal Analysis and Calorimetry》2002,70(1):9-17
Curing reactions of the epoxy system consisting of a diglycidyl ether of bisphenol A (BADGE n=0) and m-xylylenediamine (m-XDA) were studied to calculate time-temperature-transformation (TTT) isothermal cure diagram for this system. Gel times were
measured as a function of temperature using solubility test. Differential scanning calorimetry (DSC) was used to calculate
the vitrification times. DSC data show a one-to-one relationship between T
g and fractional conversion, a independent of cure temperature. As a consequence, T
g can be used as a measure of conversion. The activation energy for the polymerization overall reaction was calculated from
the gel times obtained using the solubility test (41.5 kJ mol-1). This value is similar to the results obtained for other similar epoxy systems. Isoconversion contours were calculated by
numerical integration of the best fitting kinetic model.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
107.
The synthesis of model long-chain hydrocarbons (C13 and C19) carrying a vinyl group and a trichloro- or a triethoxysilyl group at each end is reported. These compounds are suitable for linkage to a hydroxylated silicon surface and at the other end with vinyl group for further functionalization and multilayer formation. 相似文献
108.
Clovis Peppe Paola de Azevedo Mello Rafael Pavão das Chagas 《Journal of organometallic chemistry》2006,691(11):2335-2339
The organoindium compound derived from indium monobromide and dibromoacetonitrile reacts with carbonyl compounds to afford the corresponding 2-bromo-2-cyano-indium(III) alkoxide. The action of a second equivalent of indium monobromide onto the alkoxides derived from aldehydes promotes the Boord elimination of the β-related oxygen and bromine atoms leading to 2-alkenenitriles. 相似文献
109.
J. N. Spencer Jarusha DeGarmo I. M. Paul Qing He Xiaoming Ke Zhenqing Wu C. H. Yoder Shuyun Chen J. E. Mihalick 《Journal of solution chemistry》1995,24(6):601-609
Calorimetric studies of the inclusion complexes of straight and branched alcohols and of diols with alpha-cyclodextrin (-CD) have been carried out in water solvent. The data suggest that straight and branched chain alcohols enter the cavity of -CD alkyl end first. The hydroxyl group hydrogen bonds to the outer oxygen ring of the cyclodextrin. For branched chain alcohols the longer alkyl part of the molecule penetrates the -CD cavity up to the hydroxyl group. Diols form two hydrogen bonds to the outer oxygen ring of the cyclodextrin with some penetration into its interior. 相似文献
110.
The diffusion-limited reaction A+AA+B is studied in general dimension. The asymptotic decay of the system is found to depend nontrivially upon the initial concentration of A particles for certain ranges of the diffusion constant, backward reaction rate, and total concentration of particles. This nonequilibrium behavior is due to the formation of clusters centered about the initial A particles. A perturbative analysis ind=1 shows that the transition to the nonequilibrium dynamics is sharp and is quite similar to another previously studied reaction A+AA. Ford>1, a scaling argument is presented which describes the dependence of the asymptotic decay on the initial concentration of A particles and the equilibrium concentration for large backward reaction rates. Monte Carlo data are shown which confirm the analytic work ind=1, 2, and 3. 相似文献