Study on Facilitated Pertraction of Folic Acid in Pseudosteady-State Regime

The influences of the pH-gradient between the feed and stripping phases and of carrier concentration inside the membrane phase on the efficiency of facilitated pertraction of folic acid with Amberlite LA-2 in pseudosteady-state mode have been analyzed. The experiments have been carried out using a U-shaped pertraction cell which allowed to easily maintaining the liquid membrane between the two aqueous phases. On the basis of the experimental data and theoretical investigation on pseudosteady-state regime, two models describing the acid accumulation inside the liquid membrane by means of the permeability factor have been developed for two pH-values of feed phases (5.2 and 3, respectively). The proposed models offer good concordance with the experimental data and can be useful for facilitated pertraction optimization.     

Synergic Extraction of Folic Acid with Di(2-ethylhexyl) Phosphoric Acid and Amberlite LA-2

The influences of extractants concentrations and solvent polarity on the efficiency of folic acid separation by synergic extraction with Amberlite LA-2 and di(2-ethylhexyl) phosphoric acid (D2EHPA) mixture have been analyzed. The results indicated the formation of an interfacial compound which includes one molecule of folic acid and one of D2EHPA, the hydrophobicity of this compound being increased by solvation with Amberlite LA-2 molecules. The number of aminic molecules participating in the interfacial complex formation is controlled by solvent polarity and D2EHPA concentration, decreasing from 3 to 1 with the increase of these two parameters. The results indicated that the most important synergic effect corresponds to the extractants mixture dissolved n-heptane, at low D2EHPA concentration in the organic phase (5 g/l).     

多元杂多酸在仲辛醇制己酸中的催化作用

采用磷、钼、钒系列多元杂多酸作为硝酸氧化仲辛醇制己酸的催化剂,对其催化性能和选择性进行了实验研究。结果表明:H6PMo9V3O40、H10PMo5V7O40、H11PMo4V8O40等多元杂多酸均可提高仲辛醇的转化率、己酸产率和己酸选择性,并确定了这3种催化剂的最佳用量:当它们分别为仲辛醇质量的1 4%、1 0%、1 4%时,仲辛醇转化率可达98 3%、97 6%、100%;己酸的选择性可达85 7%、85 8%、78 8%;其性能明显优于钒催化剂。     

Selective Separation of Cinnamic and p‐Methoxycinnamic Acids by Facilitated Pertraction

Abstract

Cinnamic acid can be selectively separated from p‐methoxycinnamic acid by facilitated pertraction with Amberlite LA‐2 dissolved in dichloromethane, using a U‐shaped pertraction cell which allows obtaining the free liquid membrane. The pertraction has been analyzed by means of initial and final mass flows, permeability and selectivity factors. The main factors which control the pertraction selectivity were identified to be the pH‐gradient between the feed and stripping phase and the mixing intensity of the aqueous phases. The maximum selectivity factor has been recorded for pH=2 of feed phase, pH=8 of stripping phase, rotation speed lower than 300 rpm, and carrier concentration higher than 40 g/l.     

Equilibria,Kinetics, and Modeling of Extraction of Citric Acid from Aqueous Solutions with Alamine 336 in 1-Octanol

Experimental equilibrium and kinetic data on the extraction of citric acid from aqueous solutions using Alamine 336 in 1-octanol have been determined. The distribution coefficient has increased from 0.029 to 71.727 with increase of Alamine 336 concentration from 0 to 30% (v/v). The chemical equilibria was interpreted as a result of consecutive formation of acid-amine species with 1:1 stoichiometry and the equilibrium complexation constant, K _E1 , has been estimated as 20.186 m³ kmol^?1. The mass-transfer coefficients of citric acid, Alamine 336, and 1:1 acid-alamine complex in 1-octanol were calculated from acetic acid mass-transfer coefficient, which was determined by measuring its fluxes of simple diffusion from kerosene to water. Based on the Hatta number and the criterion given by Doraiswamy and Sharma, the reaction regime has been found to be instantaneous reaction regime occurring at the interface on the organic phase side. An extraction model comprising 1:1 equilibrium complextion constant, K _E1 , and complex mass-transfer coefficient, k _BA (3.79 × 10^?6 m s^?1), has been developed, and it explained the present system satisfactorily.     

Fluid-dynamic experimental study in a slurry bubble column with a tube bank in cross flow

In this work, the fluid-dynamic of a slurry bubble column provided with a tube bank operating in cross flow was studied. The main objective was to determine the influence of the air velocity, the slurry velocity, and the solid concentration in the gas holdup and solid distribution inside a bed with internals. Pilot scale equipment with a column of square traverse section (0.144 m 2 ) of stainless steel with 2.20 m height was used. The column base has a truncated pyramidal shape with an inclination angle to the vertical of 20°. In the central part of the equipment, there is a bank of 49 tubes ( D =2.54 cm and L =38 cm) in an aligned arrangement ( S_L=S_T=4.4,rm cm ). The three-phase system used was compressed air, tap water, and sieved sand ( D_p=0.0505,rm cm ). The velocities of liquid and gas phases were varied in the range from 0.31 to 1.24 cm/s and from 1.41 to 3.15 cm/s, respectively, and the solids load concentration from 0 to 30% w/w. According to the results, when the liquid and gas phase velocities increase, the gas holdup, varepsilon_G , increases, while when the solids load concentration increases, varepsilon_G presents a local maximum at intermediate values, varepsilon_G being the largest for the two-phase system. Analogously, the axial profiles of solids concentration showed a local maximum in the central region of the column, exactly in the area of the tube bank. In the traverse direction, the solids concentration increases gradually heading to the center of the column. These profiles, axial and traverse, become more uniform as the air velocity increases and the slurry as well. In addition, according to expectations, the solids concentration increases in each point of the column as the load concentration is increased in the system.     

1,6-二羟基-2-萘甲酸的合成研究

标题化合物是合成新型内分泌治疗剂的重要中间体,而其合成方法未见文献报道。以6-甲氧基-1-萘满酮为起始原料,经取代、氧化和水解3步反应得到目标产物,其结构经MS、~1HNMR、~(13)CNMR和IR确证。该路线原料廉价易得、操作简单、后处理方便,总收率达69.5%,适合工业化生产。     

2—丙烯酰胺基—2—甲基—1—丙磺酸水溶液聚合动力学研究

2-丙烯酰胺基-2-甲基-1-丙磺酸(AMPS)是重要的丙烯酰胺系阴离子单体,其均聚物和共聚物的用途甚广。本文以过硫酸钾为引发剂,研究了AMPS水溶液聚合动力学,确定R_p=k[AMPS]~(1.8)[K_2S_2O_8]~(0.8),表观活化能E_a =71.1kJ/mol。     

固体超强酸ZrO2-TiO2/SO42-催化下甲苯的区域选择性硝化

制备了ZrO2/SO4^2-、TiO2／SO4^2-和一系列不同Zr／Ti原子数比的ZrO2^-TiO2／SO4^2-固体超强酸催化剂。通过气相色谱研究了诸如催化剂的Zr／Ti原子数比、催化剂的焙烧温度、硝化反应时间、硝化反应温度及催化剂的重复使用等因素对甲苯硝酸硝化区域选择性的影响。结果表明,在醋酐存在条件下,以硝酸（质量分数为65％）为硝化剂,反应温度控制在40℃,反应进行60min,经500℃焙烧3h后的ZrO2^-TiO2／SO4^2-（Zr／Ti原子数比为1：1）固体超强酸催化剂,对甲苯表现出了强的区域选择性,甲苯硝化产物邻对位比达0.90,较硝硫混酸的1.67显著降低,产物得率达到92．9％。该催化剂可循环使用5次,催化活性基本不变,是一种具有应用前景的绿色硝化反应催化剂。     

6-氟-3,4-二氢-2H-1-苯并吡喃-2-甲酸的合成

6-氟-3,4-二氢-2H-1-苯并吡喃-2-甲酸是制备新型抗高血压药奈必洛尔的关键中间体.今以4-氟苯酚为起始原料,经酯化、Fries重排、环化、氢化等6个步骤得到目标产物,总收率27%.4-氟苯酚Ⅰ与乙酸酐酯化得4-氟苯基乙酸酯Ⅱ,Ⅱ在AlCl3催化下Fries重排得4-氟-2-乙酰基苯酚Ⅲ,比从4-氟苯酚的Friedel-Crafts酰化收率更高,二步总收率58%;Ⅲ与酰化试剂乙二酸二乙酯经酯化、环合及碱性水解得到6-氟-4-氧代-4H-1-苯并吡喃-2-甲酸Ⅵ,用一种试剂完成了酰化、环化并引入羧基;Ⅵ在乙酸介质中,以10%Pd/C催化加氢得外消旋6-氟-3,4-二氢-2H-1-苯并吡喃-2-甲酸Ⅶ.以上所述的方法具有条件温和、试剂常见易得、易于工业化的优点,并首次给出了关键中间体及目标产物的光谱图,表明产物结构正确.     

催化氧化合成4-氯-2-硝基苯甲酸

本文介绍了一种新型硝酸氧化催化剂PM-1,并以4-氯-2-硝基苯甲酸的合成为例加以说明,对反应温度、反应时间、催化剂用量等加以讨论,得出最佳反应条件:反应温度160～170℃,反应时间13小时,4-氯-2-硝基甲苯:催化剂=20∶1(重量比)。     

N-(1-丁基-2-吡咯甲酰基)氨基酸甲酯的合成

在室温下,氨基酸甲酯和1-丁基-2-三氯乙酰基吡咯经酰基化反应,以81.3%~87.1%的产率,合成了系列N-(1-丁基-2-吡咯甲酰基)氨基酸甲酯,通过1HNMR,IR,MS和元素分析对其结构进行了表征。     

2-[(1-羟基-2-萘基)羰基]苯甲酸的合成与表征

以苯酐和-α萘酚为原料,在B2O3催化下合成了2-[(1-羟基-2-萘基)羰基]苯甲酸,反应的优化条件为:n(B2O3)∶n(苯酐)∶n(-α萘酚)=1.5∶1.5∶1,反应温度为180￣190℃,反应时间为2.0h,收率达97.8%,并通过元素分析、1H NMR、IR、EIMS对产物结构进行了表征。     

溶剂法合成2-羟基-1-萘甲酸的工艺研究

以β-萘酚和氢氧化钠为原料,正辛烷为溶剂,合成了2-羟基-1-萘甲酸,纯度达98％以上。通过正交实验研究了反应压力、反应温度和反应时间对收率的影响,确定了最佳的工艺条件：反应压力0．8MPa,反应温度90℃,反应时间8h,该条件下收率达82．83％。     

固体超强酸SO_4~(2-)/TiO_2-SiO_2催化合成马来酸二辛酯

用H2 SO4浸渍钛硅复合氧化物 ,制得固体超强酸SO2 -4/TiO2 -SiO2 ,考察了催化剂对马来酸酐与正辛醇的酯化反应的催化作用及其制备条件对催化剂活性的影响 ,并与硫酸、对甲苯磺酸的催化效果比较。结果表明 :对于给定反应 ,当n(Ti)∶n(Si)为 15∶1、用浓度 0 .6mol/L的硫酸浸渍 8h、在 5 5 0℃下焙烧 3h时制得的催化剂SO2 -4/TiO2 -SiO2 具有最高的催化活性 ;用以催化马来酸酐和正辛醇的酯化反应 ,可得无色透明的酯化产物 ,3h内酯化率达 99.1% ;较SO2 -4/TiO2 催化剂的酯化率提高了约 6 %     

Modeling of Facilitated Transport of Phenylalanine by Emulsion Liquid Membranes with Di(2-ethylhexyl)phosphoric Acid as a Carrier

ABSTRACT

A mathematical model is developed in this paper to simulate the facilitated transport of phenylalanine (Phe) in emulsion liquid membrane (ELM) systems with di(2-ethylhexyl)phosphoric acid as a carrier. The model takes into account the mass transfer in both the external aqueous phase and the organic membrane phase interfacial reaction as well as membrane breakage during agitation. The model is tested by comparing theoretical predications with experimental results using Phe extraction by ELM processes. It is found that the model is valid for simulating the facilitated transport of Phe with ELM under various experimental conditions.     

溶剂法合成2-羟基-1-萘甲酸的工艺研究

以β-萘酚和氢氧化钠为原料,正辛烷为溶剂,合成了2-羟基-1-萘甲酸,纯度达98%以上。通过正交实验研究了反应压力、反应温度和反应时间对收率的影响,确定了优化的工艺条件:反应压力0.8 MPa,反应温度90℃,反应时间8 h,该条件下收率达82.83%。     

Photocatalyzed Degradation of Phenol, 2,4-Dichlorophenol,Phenoxyacetic Acid and 2,4-Dichlorophenoxyacetic Acid over SupportedTiO2 in a Flow System

The photodegradation of phenol, 2,4-dichlorophenol, phenoxyacetic acid and 2,4-dichlorophenoxyacetic acid using TiO₂ as photocatalyst is investigated. The photodegradations of these compounds have been conducted in a continuous mode by means of a flow system, in which TiO₂ remains fixed onto glass pearls. The use of this system gives high yields of degradation for the chemicals tested, except for 2,4-dichlorophenol for which a slow dechlorination process is observed. The rate of photodegradation depends on the pH of the solution, the point of zero charge of TiO₂ and the pK_a of the chemicals being the key parameters. The main aromatic intermediates detected have been hydroquinone,paraquinone and hydrohydroquinone during phenol degradation; phenol and hydroquinone during phenoxyacetic acid degradation; chlorohydroquinone and chlorophenol during 2,4-dichlorophenol degradation; and dichlorophenol during 2,4-dichlorophenoxyacetic acid degradation. Finally, some long term irradiations with phenol as model compound have been performed, showing high degrees of photodegradation. It has been observed that only a periodic evacuation of the effluent out of the reactor is needed to sustain high percentages of photodegradation.