异丙醇-ClO^--H_2O_2化学发光体系测定痕量乙醛的研究

C1O^--H_2O_2可强烈氧化某些有机物而发光,碱性介质中的异丙醇也可被ClO^--H_2O_2氧化产生化学发光,乙醛的存在可显著增强该体系的化学发光效果,且被敏化的化学发光强度与一定范围内的乙醛浓度有良好的线性关系,依据上述关系,我们建立了用于测定痕量乙醛的新方法,该法具有较高的灵敏度,检出限为1.0×10^(-10)g/mL乙醛,线性响应范围大于3个数量级,将此法应用于测定有机化工厂废水中的乙醛,结果满意。

Anodic dissolution behavior of zirconium in Bu_4~nNBr-containing isopropanol solution

Anodic dissolutionbehaviorof zirconium inBu^n 4NBr-contaningisopropanol solution was investigated using cyclic voltammetry, linear sweep voltammetry and chronoamperometry, complemented with a scanning electron microscope （SEM）.The voltammograms did not exhibit active dissolutionuntil the breakdown of passive layer induced by aggressive bromide anions.SEM images confirmed the existence of pits on zirconium surface.The depth and breadth of pits were intensified with increasing potential. The pitting potentialshifted negatively as either temperature orBu^n 4NBr concentration was increased, while it increased with increasing scan rate.The corrosion current density increased with increasing temperature. The apparent activation energyof anodic dissolutionofzirconiumwas 21.88kJ/mol. The chronoamperometry revealed that increasingBu^n 4NBrconcentration shortened the incubation time for passivity breakdown and accelerated the pit nucleation and growth. The experimental results were helpfulto obtain the optimum conditions for electrosynthesis of zirconium isopropoxide.

1-氧-正十八烷基-2-氧-甲基-sn-甘油合成工艺改进

以二异丙叉-D-甘露醇为手性源,经高碘酸钠氧化断键后再经硼氢化钠还原制得 S-(D)-1,2-氧-异亚丙基-sn-甘油,再经过4-甲氧基苄基(PMB)保护,脱去丙叉,经二叔丁基氧锡选择性正十八烷基化,2位甲基化,最后脱去 PMB 保护,制备目标化合物1-氧-正十八烷基-2-氧-甲基-sn-甘油,以1,2;5,6--二-丙叉-甘露醇计,七步反应后总收率达55%。

An Isopropyldioxy Flavonol from Hypericum perforatum L.

Aim Isolation and structural elucidation of the constituents from the aerialpart of Hypericum perforatum L. Methods Column chromatography and TLC were used to isolate chemicalconstituents. Physico-chemical characterization and spectroscopic analysis were employed forstructural identification. Results Three flavonols were isolated and identified. Conclusion Compound1 is a novel natural product and its structure has been characterized to be 3, 5, 7-trihydroxy-3',4'-isopropyldioxy-flavone.

Synthesis of graphene/tourmaline/TiO_2 composites with enhanced activity for photocatalytic degradation of 2-propanol

We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.

Synthesis,characterization and application of PVA/ionic liquid mixed matrix membranes for pervaporation dehydration of isopropanol

In this study,polyvinyl alcohol(PVA)–ionic liquid(IL) membranes were prepared for the separation of isopropyl alcohol(IPA)–water azeotropic mixtures by pervaporation.PVA-IL composite membranes were prepared by simple solvent evaporation method using four ILs,viz.,1-n-butyl-3-methylimidazolium chloride(BMIMCl),1-hexyl-3-methylimidazolium chloride(HMIMCl),1-hexyl-3-methylimidazolium tetra fluoroborate(HMIMBF4) and 1-octyl-3-methylimidazolium chloride(OMIMCl).Three ILs were used to study the effect of alkyl chain on the pervaporation performance.The study had focused on the effect feed water concentration from 10%–40%and effect of feed temperature from 50–80°C.Physiochemical properties of all the membranes were studied using Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and contact angle measurement.The Arrhenius activation energies for permeation were estimated to be in the range 4–12 kJ·mol-1 from the temperature dependent permeation values.

Transport Process of Isopropanol Aqueous Solution by Pervaporation

To study the transport process of isopropanol aqueous solution by pervaporation, the transport model of isopropanol and that of water at 323 K in polyvinyl alcohol(PVA) membrane were obtained in this paper. Theoretical predictions agreed well with the experimental results. The interactional parameter between water and PVA membrane is less than that between isopropanol and PVA membrane, which shows that water is preferentially dissolved in PVA membrane. The plasticizing coefficient and diffusion coefficient at infinite dilution of water are larger than those of isopropanol, which shows that the dissolution and permeation in PVA membrane of water are greater than those of isopropanol. Both the interactional parameter between water and isopropanol in the membrane and that in feed rise with the increase of isopropanol content in feed, which shows that the larger isopropanol content is, the higher selectivity of the membrane is and the more remarkable separation effect of pervaporation is.

Synthesis and Separation Performance of Y-type Zeolite Membranes by Pre-Seeding Using Electrophoresis Deposition Method

Y-type zeolite membranes were synthesized by a two-step approach in which a particle seed layer was prepared by electrophoresis deposition(EPD) at first, followed by densification through secondary growth. The pre-seeding adopted the directing agent for Y-type zeolite synthesis serving as seeds. The effects of aging time of the directing agent, electrophoresis voltage and electrophoresis deposition time on seed layers quality as well as the quality of zeolite membranes were investigated. The results indicated that the zeolite seeds derived from the directing agent could be evenly deposited on substrate under certain EPD conditions. The XRD patterns of the seeded substrates after the secondary growth showed that the pure as-synthesized Y-type zeolite membranes had successfully grown on the substrates. The SEM images indicated that the substrate was covered by the highly intergrown zeolite crystals when the seeding solution employed the directing agent with an aging time of 2 days. The separation performance of zeolite membrane was evaluated using a CO_2/N2 mixture(with a mole ratio of 1:1) at different temperatures. Furthermore, the pervaporation measurements were carried out for the dehydration of isopropanol aqueous solutions with different mass fractions. The as-synthesized Y-type zeolite membranes exhibited a relatively high selectivity of water from isopropanol and sustainable permeation flux.

THE FABRICATION OF CARBON AEROGELS BY GELATION IN ISOPROPANOL WITH BASIC CATALYST

A new method for the fabrication of carbon aerogels is reported in this paper. Resorcinol and furfural were gelated in isopropanol with basic catalysts and then dried directly under isopropanol supercritical condition, followed by carbonization under nitrogen atmosphere. The bulk densities of carbon aerogels obtained are in the range of 0.21g/cm3~0.27g/cm3 and the sizes of the interconnected carbon nano-particles are in the range of 20nm^30nm. All of the aerogel samples exhibit high BET surface areas in the range of 730m2/g^900m2/g. The bulk density, micro-pore volume, meso-pore volume and meso-pore diameter can be controlled by gelation conditions such as R/I ratio and R/C ratio.

Study on Salt-Containing Extractive Distillation for the 2-Propanol/Water System

The salt-containing extractive distillation column and the salt-containing agent recovery column for the 2-propanol/water/ethanediol/KAc system were simulated by the NRTL model and the modified Rose Relaxation method. The simulation results showed that prediction of the salt effect in vapor-liquid equilibrium and the correlation method （TDCM） of NRTL parameters were suitable for the said system. Four different distillation technology processes were investigated; the results showed that the salt-containing extractive distillation process was the best one. The simulating design of the extractive distillation column was performed under the conditions of different total stage number, feeding location, reflux ratio, amount of mixed agent and concentration of KAc. The results showed that such factors as 17 stages, a feeding location at the 9th stage, a reflux ratio of 1.2, and a mixed agent feeding rate of 1.141 kmol/h, might be the best suited operating conditions. The simulating design was also done for the column for recovering the salt-containing agent. The simulation method of the salt-containing extractive distillation is simple and effective in this work.

Acetone Formation from Photolysis of 2-Propanol on Anatase-TiO2（101）

Photocatalysis of 2-propanol on A-TiO2（101） has been investigated using a temperature programed desorption method with 266 nm laser light. A clear mechanism is proposed for photodissociation of 2-propanol on A-TiO2（101）. Acetone product on five coordinate Ti4＋ sites is formed in a stepwise manner in which the O-H dissociation proceeds first and then followed by secondary C-H dissociation of 2-propanol while H atoms are transferred to the adjacent bridge bond oxygen （BBO） sites. Low temperature water is formed in a thermally driven process via H-atom on BBO in exchange with isopropyl groups of molecule 2-propanol, while isopropyl radical desorbs at high temperature during the TPD process. The observation demonstrates the prospect of TiO2 as a photocatalyst for degradation of organics.

Rhodium(Ⅲ)-catalyzed selective access to isoindolinones via formal [4+1] annulation of arylamides and propargyl alcohols

A mild and efficient oxidative synthesis of isoindolinones has been realized by Rh(III)‐catalyzed C?H activation of benzamides and[4+1]coupling with propargyl alcohols.This coupling system proceeds with broad substrate scope and mild conditions and provides a new approach to access the useful skeleton ofγ‐lactams with a stereogenic center.

Solubilities of Nizatidine in Methanol+Water, Ethanol+Water and i-Propanol+Water from 273.15 to 303.15 K

The solubilities of nizatidine in methanol + water, ethanol + water and i-propanol + water mixtures were determined in the temperature range from 273.15 K to 303.15 K at atmospheric pressure by a static analytical method. The general single model was used to correlate the experimental data, which fits the data very well.

The Swelling Equilibria of N-isopropylacrylamide Based Hydrogel in Aqueous Solution of Ethanol

N-isopropylacrylamide (NIPAAm) was used to synthesize NIPAAm homopolymer (nonionized) and NIPAAm-sodium methacrylate copolymer (ionized). The swelling equilibria for both gels were obtained in aqueous solution of ethanol with concentration ranging from 0 to 100%(by mass) at 25℃. The swollen gel in water shrank first with the addition of a small amount of ethanol and then reswelled with further addition of ethanol showing not only a discontinuous volume phase transition but also a typical reentrant phenomenon. A thermodynamic model based on the UNIQUAC with the 'free-volume' contribution was applied to correlate and predict the swelling behavior of the poly(NIPAAM)-gels in ethanol-water mixture.

Single-atom Fe with Fe_(1)N_(3) structure showing superior performances for both hydrogenation and transfer hydrogenation of nitrobenzene

The design of non-noble metal heterogeneous catalyst with superior performance for selective hydrogenation or transfer hydrogenation of nitroarenes to amines is significant but challenging.Herein,a single-atom Fe supported by nitrogen-doped carbon(Fe_(1)/N-C)catalyst is reported.The Fe_(1)/N-C sample shows superior performances for the selective hydrogenation and transfer hydrogenation of nitrobenzene to aniline at different temperatures.Density functional theory(DFT)calculations show that the superior catalytic activity for the selective hydrogenation at lower temperatures could be attributed to the effective activation of the reactant and intermediates by the Fe_(1)/N-C.Moreover,the excellent performance of Fe_(1)/N-C for the selective transfer hydrogenation could be attributed to that the reaction energy barrier for dehydrogenation of isopropanol can be overcome by elevated temperatures.

Experimental Study of Isopropanol Dehydrogenation over Amorphous Alloy Raney Nickel Catalysts

The dehydrogenation reaction of isopropanol occurring at low temperature is of great industrial importance. It is a key procedure in isopropanol/acetone/hydrogen chemical heat pump system. An experimental investigation was performed to study the behavior of the liquid phase dehydrogenation of isopropanol over amorphous alloy Raney nickel catalysts. Un-promoted and promoted catalysts were used and their performances were compared under various catalyst amounts, acetone content in the reactant and reaction temperature ranging from 348 K to 355 K.It is found that there exists an optimum catalyst concentration which is about 0.34 g in 300 ml isopropanol. The temperature has evident effect on the reaction. The presence of activities of Fe-promoted catalyst decrease slightly compared to the un-promoted catalyst when the temperature are 348 K and 351 K. Besides, the reaction rate decreases almost linearly with the increase of acetone volume fraction in the reactant.

大花红景天中化学成分的研究

目的对大花红景天中的化学成分进行研究。方法以体积分数80%乙醇对大花红景天进行提取,提取物经乙酸乙酯萃取后,采用各种柱色谱技术进行分离,利用NMR,MS等光谱学方法进行结构鉴定。结果从大花红景天中分离鉴定了11个化合物,分别为9,9'-丙叉基异落叶松脂醇(1),对羟基苯丙烯酸(2),对羟基苯丙烯酸4-O-β-D-葡萄糖苷(3),Tachioside(4),二氢松柏苷(5),2-苯乙基-1-O-β-D-葡萄糖苷(6),2-苯乙基-1-O-β-D-葡萄糖-(1→6)-α-L-吡喃阿拉伯糖苷(7),2-苯乙基-1-O-β-D-葡萄糖-(1→6)-α-L-呋喃阿拉伯糖苷(8),2-苯乙基-1-O-β-D-葡萄糖-(1→6)-β-D-木糖苷(9),1-苯甲基-1-O-β-D-葡萄糖苷(10),rhodiocyanoside D(11)。结论所有化合物均首次从该植物中分离得到,且化合物1,3,4,5,7,9为首次从该属植物中分离得到。

Inhibition of phosphoenolpyruvate carboxykinase gene expression by metformin in cultured hepatocytes

Objective To investigate the effect and mechanism of the antihyperglycemic agent metformin on the expression of phosphoenolpyruvate carboxykinase (PEPCK) gene in hepatocytes and to determine whether the effects of metformin in hepatocytes are transmitted throughout the known insulin signaling pathways Methods Confluent H4IIE rat heptoma cells were cultured for 16 h with 0 1 mmol/L metformin either in absence or presence of 0 1 nmol/L insulin, and then stimulated with various agents The expression of PEPCK gene was examined by Northern blot analysis Results Therapeutic concentrations of metformin significantly inhibited basal PEPCK mRNA expression and also decreased cAMP and dexamethasone induced PEPCK gene expression through interaction with insulin In the presence of insulin signaling pathway inhibitors wortmannin and UO126, metformin reduced PEPCK mRNA levels, but wortmannin blocked inhibitory regulation of insulin on PEPCK gene expression Conclusion Metformin inhibits PEPCK gene expression via either an insulin independent or an interacting with insulin manner The results suggest that a possible mechanism by which metformin reduces gluconeogenesis could be associated with the inhibition of PEPCK gene expression