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61.
Charles E. McKenna Boris A. Kashemirov Mari Fujimolo 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Individual E/Z isomers of the C-methyl ester 1 of α-(hydroxyimino)phosphonoacetic acid (“troika acid”) were recently prepared as dicyclohexylammonium salts and found to be stable at neutral pH.1 On alkaline demethylation followed by pH adjustment to 6–7, E?1 and Z?1 stereospecifically undergo P-Cαand Cα-Cβ cleavage, respectively.1 Herein we report synthesis of the corresponding P-methyl ester from trimethyl phos-phonoacetate 2. The product was isolated as its bis-DCHA+ salt E-3, with stereochemistry assigned by NMR.2 相似文献
62.
Boris A. Kashemirov Mari Fujimoto-posner Charles E. McKenna 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract The (E-oxime of phosphonoglyoxylic acid, or (E-troika acid [(E)-l] undergoe: fragmentation leading to phosphorylation of the aqueous solvent at neutral pH and room temperature.[1] In contrast, the corresponding C-methyl ester (a-2 is stable under these mild conditions. Conversion of the unreactive (E)-2 to (E)-1 requires dewthylation a pH 13–14, generating the polyanion of (E-1, which becomes reactive on protonation.[1] 相似文献
63.
64.
Ben Xu Xiaojun Di Gregory B. McKenna 《Journal of Thermal Analysis and Calorimetry》2013,113(2):539-543
The melting temperature depression of pentaerythritol tetranitrate, nanoconfined in controlled pore glasses (CPG), was systematically studied by differential scanning calorimetry (DSC). The solid–liquid interfacial energy σ sl was obtained from the Gibbs–Thomson equation fit to melting temperature vs. reciprocal pore diameter. The pore size distribution of the CPG pores was also estimated from the DSC data. Pore sizes obtained from the manufacturer by BET are compared with those determined from the DSC curves using either the curves directly or by assuming spherical shaped confining cavities. The thermal mass vales are in better agreement with the BET estimation. 相似文献
65.
A synthesis of the naturally occurring bicyclic acetal, “exobrevicomin” is described. The requisite threo stereochemistry of keto diol precursors is obtained selectively by condensation of a gamma-alkoxy allylboronate with an appropriate aldehyde. 相似文献
66.
The selective reduction of aryl nitro compounds in the presence of sensitive functionalities, including halide, carbonyl, nitrile, and ester substituents, under ultrasonic irradiation at 35 kHz is reported in yields of 39–98%. Iron powder proved superior to stannous chloride with high tolerance of sensitive functional groups and high yields of the desired aryl amines in relatively short reaction times. Simple experimental procedure and purification also make the iron reduction of aryl nitro compounds advantageous over other methods of reduction. 相似文献
67.
Sean Stokes & Keith T. Mead 《合成通讯》2013,43(19):2627-2633
A route to aryl-substituted quinolines from N-tosyl 1-azadienes is described. The key steps are a [4 + 2] cycloaddition with benzyne followed by base treatment of the 1,4-dihydroquinoline product. The N-tosyl 1-azadienes were prepared from readily accessible cinnamaldehyde and chalcone substrates by condensation with p-TsNH2. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
68.
69.
Adrián Serrano Mora Sean T. McBeath Clément A. Cid Michael R. Hoffmann Nigel J.D. Graham 《Current Opinion in Electrochemistry》2022
While diamond electrodes have been commonly used to generate ?OH to treat a variety of persistent water and wastewater micropollutants, mass transfer limitations and the non-selective, short-lived nature of the ?OH restrict the degradation to the solution at, or near, the electrode surface. However, diamond electrodes can generate oxidizing species that facilitate micropollutant degradation in the bulk water solution. These include persulfate, sulfate radicals, peroxodiphosphate, ferrate, permanganate, reactive chlorine species, hydrogen peroxide, and ozone, which have been reported during electrochemical treatment of water with diamond electrodes. Although still restricted to specialized applications, recent studies, summarized in this review, have proven the electrogeneration of these additional oxidant species to be effective. They have shown the adaptability and potential of diamond electrode-based water treatment to mitigate the presence of micropollutants in water. 相似文献
70.
Timothy D. OFlynn Sean A. Hogan David F. M. Daly James A. OMahony Noel A. McCarthy 《Molecules (Basel, Switzerland)》2021,26(10)
Soy protein isolate (SPI) powders often have poor water solubility, particularly at pH values close to neutral, which is an attribute that is an issue for its incorporation into complex nutritional systems. Therefore, the objective of this study was to improve SPI solubility while maintaining low viscosity. Thus, the intention was to examine the solubility and rheological properties of a commercial SPI powder at pH values of 2.0, 6.9, and 9.0, and determine if heat treatment at acidic or alkaline conditions might positively influence protein solubility, once re-adjusted back to pH 6.9. Adjusting the pH of SPI dispersions from pH 6.9 to 2.0 or 9.0 led to an increase in protein solubility with a concomitant increase in viscosity at 20 °C. Meanwhile, heat treatment at 90 °C significantly improved the solubility at all pH values and resulted in a decrease in viscosity in samples heated at pH 9.0. All SPI dispersions measured under low-amplitude rheological conditions showed elastic-like behaviour (i.e., G′ > G″), indicating a weak “gel-like” structure at frequencies less than 10 Hz. In summary, the physical properties of SPI can be manipulated through heat treatment under acidic or alkaline conditions when the protein subunits are dissociated, before re-adjusting to pH 6.9. 相似文献