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A convenient, economical, and practical protocol for borax-catalyzed thiolysis of 1,2-epoxides in aqueous medium has been developed, which has greatly expanded the utility scope of borax in organic synthesis. 相似文献
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记录了硼砂饱和溶液的差示FTIR光谱和Raman光谱 ,分别对其FTIR吸收波数和Raman位移进行了归属。该溶液中硼的存在形式有H3 BO3 ,B(OH) -4,B3 O3 (OH) 2 -5,B4O5(OH) 2 -4等。提出了硼砂饱和溶液中硼氧配阴离子的存在形式及其与析出Na2 B4O7·10H2 O固相的关系。 相似文献
3.
柱前衍生-高效液相色谱法测定香精香料中硼酸和硼砂 总被引:1,自引:0,他引:1
香精香料样品中的硼酸经姜黄素的乙酸溶液在室温下进行衍生化,所得硼的衍生物用高效液相色谱法分析。选用Hypersil ODS2色谱柱(4.6mm×250mm,5μm)为固定相,以甲醇与0.012mol·L-1四丁基溴化铵(TBABr)溶液按体积比80比20混合所得溶液为流动相进行淋洗,于波长550nm处进行检测。根据硼砂在硫酸环境下定量转化成硼酸的原理间接测定硼砂。硼的色谱峰面积与其质量浓度在0.004~0.2 mg·L-1范围内呈线性关系,检出限(3s)为4.0×10-4 mg·L-1。在3个浓度水平下做加标回收试验,所得硼酸和硼砂的平均回收率分别在92.1%~106.6%和92.9%~107.1%之间。 相似文献
4.
Flotation is one of the plausible methods for recovering borax fines discharged as fine waste to the tailings dam in the Kirka borax processing plant. A literature review dealing with the flotation behavior of boron minerals reveals that clay minerals in the boron ores coat boron minerals and thus deteriorate the quality of boron concentrates produced by direct flotation. The main objective of this study is therefore to recover borax fines from the tailings of the concentrator by reverse flotation. A three-level-factor experimental design was used to determine the main and interaction effects of variables selected on the metallurgical performance of reverse flotation. An analysis of variance for experimental results indicates that interaction effects of the variables for concentrate quality and recovery of B2O3 is nonsignificant and the most important variable for grade of concentrate and recovery is the collector dosage. It is shown that a concentrate assaying 11.25% B2O3 with 89.90% B2O3 recovery could be produced by means of single-stage (rougher) reverse flotation. Additionally, in order to produce a sufficient-quality concentrate, a multistage reverse flotation scheme involving rougher, scavenger, and two cleaners was devised. A final concentrate containing 23.47% B2O3 with 81.78% B2O3 recovery was obtained from these tests. The reverse flotation method can be thus considered as an important option for the beneficiation of borax fines. 相似文献
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An efficient, borax-catalyzed protocol for the synthesis of novel 4-aryl-substituted-4H-pyran derivatives fused to α-pyrone ring in a one-pot is described. By this achievement, some novel 4-aryl substituted 4H-pyrans fused to the α-pyrone ring as potential acetylcholinesterase inhibitors (AChEIs) with good to excellent yields are obtained from a one-pot three-component reaction between various aryl aldehydes, 4-hydroxy-6-methyl-2H-pyran-2-one and malononitrile. The method is a facile, inexpensive, practical and highly efficient one to obtain target compounds. The chemical structures of all compounds were characterized by FT-IR, FT-13CNMR and FT-1HNMR, MS spectroscopy and also elemental analyses data. Furthermore, the purity of all novel compounds was checked by HPLC. In addition, both molecular modelling studies and Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMETox) prediction nominated all compounds as good acetylcholinesterase inhibitors to the potential treatment of Alzheimer, Parkinson and Autism diseases that among them compound 4f showed the best activity against acetylcholinesterase enzyme. 相似文献
6.
苯酚的电化学氧化及测定 总被引:10,自引:0,他引:10
本文研究了在硼砂介质中,苯酚及其衍生物 的电化学行为,利用苯酚在-0.5V吸附富集,再进行氧化溶出,建立了测定苯酚的新方法。 相似文献
7.
The reentrant behavior of Poly(vinyl alcohol) (PVA)–borax aqueous semidilute solutions with a PVA concentration of 20 g/l
and borax concentrations varies from 0.0 to 0.20 M was investigated using dynamic light scattering (DLS) and dynamic viscoelastic
measurements. Two (fast and slow modes) and three (fast, middle, and slow) relaxation modes of PVA semidilute aqueous solutions
without and with the presence of borax, respectively, were observed from DLS measurements. The fast and middle relaxation
modes were q
2-dependent (q is the scattering vector) characteristic of diffusive behavior; however, the slow modes were q
3-dependent, characteristic of intraparticle dynamics. The experimental results showed that the slow relaxation mode dominates
the DLS relaxation. The DLS slow mode relaxation time, τs, and the viscoelastic modulus G′(ω) and G′′(ω) data had a similar trend and demonstrated reentrant behavior as the borax concentration was increased from 0.0 to 0.20 M,
i.e. τs, G′(ω), and G′′(ω) fluctuated with increasing borax concentration. The excluded-volume effect of polymers, charge repulsion among borate
ions bound on PVA molecules, and intermolecular cross-linking didiol–borate complexation caused an expansion of the polymer
chain; however, the screening effect of free Na+ ions on the negative charge of the borate ions bound on PVA and intramolecular cross-linking didiol–borate complexation led
to a shrinkage of the polymer chain. The reentrant behavior was the consequence of the balance between expansion and shrinkage
of the PVA–borate complex.
Received: 26 March 1999/Accepted in revised form: 3 September 1999 相似文献
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Tommasina Coviello Laura Bertolo Pietro Matricardi Antonio Palleschi Gianfranco Bocchinfuso Adriana Maras Franco Alhaique 《Colloid and polymer science》2009,287(4):413-423
The peculiar unidirectional elongation observed during swelling of tablets prepared with scleroglucan (Sclg) and borax was
compared with that of other synthetic and natural polymers capable of physical/chemical interactions with borate ions. A dynamomechanical
characterization of “squared” Sclg/borax tablets was carried out to study the differences detectable on the two sides of the
matrix corresponding to the two directions, respectively, the parallel and perpendicular one with respect to the applied compression
force. Different compression forces were used and, in some cases, a second compression was applied on the tablets along a
direction perpendicular to the first one. Birefringence experiments were carried out on the swelled tablets along the two
directions. Obtained results allow correlating the anisotropic swelling behavior with the detected dynamomechanical and optical
properties of the Sclg/borax system. Among the various tested polymers, only guar gum and, to a lesser extent, locust bean
gum, showed an anisotropic elongation during swelling. 相似文献
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