Gemeinsame kondensation von phenol,melamin und formaldehyd. III. Vorkondensation

The condensation reaction between phenol, melamine, and formaldehyde at different conditions (pH-value, molar ratio of phenol and melamine) was investigated. Gel permeation chromatography, ¹³C NMR-spectroscopy and thermogravimetry showed the reactivity of phenol in the reaction with formaldehyde to be rather small at low pH values. At alkaline conditions this reactivity rises very fast. Melamine shows an inverse behaviour. Therefore neither at acidic nor at alkaline conditions cocondensates between melamine and phenol with formaldehyde are formed. Condensation, which involves both melamine and phenol, can be performed at pH-values between 6 and 9. In this range, the reaction can be controlled via acetone dilutability and turbidimetric titration.     

析相微萃取-分光光度法测定化妆品中痕量铅

采用1 -(2-吡啶偶氮)-2-萘酚(PAN)为螯合剂,四氯化碳为萃取剂,丙酮为助溶剂,建立了析相微萃取-分光光度法测定化妆品中痕量铅的分析方法,并对影响络合反应和相分离的各种条件进行了优化.优化后的条件为:当水相体积为21.5 mL时,四氯化碳为2.0 mL,丙酮为1.5 mL,萃取时间为10 min.铅的质量浓度在0.20～13 μg/mL范围内与吸光度呈线性关系,相关系数为0.999 81,方法的检出限为0.01 μg/mL,对铅的质量浓度为1.0 μg/mL的样品溶液进行7次平行测定,相对标准偏差为1.98％.该方法用于化妆品中铅的测定,回收率为96.4％ ～ 103.4％.     

固体酸H2SO4-SiO2催化合成双酚A

用溶胶-凝胶法制备了负载型固体酸H₂SO₄-SiO₂,将其用于合成双酚A的催化剂。结果表明,固体酸H₂SO₄-SiO₂是苯酚与丙酮缩合合成双酚A的高效催化剂,丙酮的转化率为94.0%,双酚A的选择性达91.0%。探讨反应温度、原料配比、反应时间以及缩合反应中生成的水对催化反应的影响。     

工艺条件对丙酮高选择性一氯化反应的影响

采用填料塔作为氯化反应器,在塔内全回流的丙酮与氯气进行反应,实现了丙酮的高选择性一氯化。研究了水量及气速对一氯化选择性反应的影响。结果表明：水与丙酮体积比为１∶１５０时,产物中一氯丙酮的含量达到最大值;尽量低的通氯速率对避免重复氯化反应有利,在１７ｇ／ｈＣｌ２的条件下,所得产品中一氯丙酮的质量分数高达９３．８５％。另外,反应速度随氯气气速的增大而增大     

2甲-基吡啶在丙酮-水混合溶剂中的电氧化

在质子交换膜为隔膜的电解槽内,以2甲-基吡啶为原料,在丙酮/水混合溶剂中,以PbO2为阳极,电氧化合成了2-吡啶甲酸。通过循环伏安、线性扫描伏安和恒电位电解实验,考察了丙酮与水体积比、反应温度、硫酸浓度、反应物2-甲基吡啶浓度和阳极电位对选择性和电流效率的影响。结果表明,V(丙酮)∶V(水)=3∶1,硫酸浓度1.0~1.2 mol/L,2甲-基吡啶浓度0.5 mol/L,温度30℃,阳极电位1.75~1.80 V,生成2吡-啶甲酸的选择性可达88.7%,电流效率达到48.3%。而在纯水作溶剂的溶液中,相同条件下生成2-吡啶甲酸的选择性和电流效率仅分别为67.4%和42.2%。     

The simulated moving-bed reactor for production of bisphenol A

Bisphenol A was produced from acetone and phenol over an ion-exchange resin catalyst at 50–90°C. Phenol was used as solvent. The reaction proceeded under the excess phenol condition. The reaction rate was proportional to the acetone concentration in the initial period of the reaction. After the acetone conversion exceeded approximately 50%, the reaction rate became lower than expected by the first-order reaction rate. This was ascribed to water adsorption onto the resin. Batch adsorption and breakthrough experiments showed that water was adsorbed approximately seven times stronger than acetone and that bisphenol A was not adsorbed. Using the reaction rate equation for bisphenol A production, the adsorption isotherms and overall mass transfer coefficients of the components, the numerical simulation of the 3-zone-type simulated moving-bed reactor was carried out. High resin flow rate was required in order to remove water out of the reaction zone, and a high liquid flow rate was also required to desorb water from the resin in the recovery zone. As far as the flow rates were set appropriately, water was successfully removed to prevent the catalyst deactivation and the long-term stable production of BPA was allowed.     

Practical two-step chain extension method to prepare sulfonated waterborne polyurethanes based on aliphatic diamine sulphonate

We reported a novel synthesis route to fabricate sulfonated aliphatic waterborne polyurethane dispersions (SWPU) only based on 2-[(2-aminoethyl) amino] ethane sulphonate sodium (AAS-Na) by two-step chain extension method with the assistance of acetone and water cosolvent. When AAS-Na was added, only less than 50% of AAS-Na was incorporated into polyurethane chain in the first-step chain extension and the residual AAS-Na formed molecular aggregates which were insoluble in acetone due to the high polarity of AAS-Na. Subsequently, the mixture of acetone and water was added, the residual AAS-Na aggregates dissolved, undertaking the further second-step chain extension reaction, and the ultimate reaction conversion of AAS-Na rose to more than 90%. The mechanism for acetone and water cosolvent to affect the preparation of SWPU dispersions was studied, as well as the water resistance, mechanical properties and hydrolysis resistance of as-prepared SWPU dispersions. With the decrease of AAS-Na content from 2.0% to 1.2%, the peak area of the melting peaks for SWPU films increased, as well as the water resistance. And the as-prepared polyester SWPU exhibited good hydrolytic stability.     

藻类叶绿素a提取的优化研究

叶绿素a是参与光合作用的基础物质，是衡量水体藻类生物量以及评价湖泊富营养化的重要指标之一。利用90%丙酮、无水乙醇、无水乙醇∶90%丙酮（1∶1）、无水乙醇∶90%丙酮（1∶2）、无水乙醇∶90%丙酮（2∶1）五种有机溶剂萃取已知浓度标准叶绿素a和叶绿素b，对传统萃取叶绿素a的计算公式加以修正，并且在超声辅助破碎藻细胞的前提下分析了该五种有机溶剂对普通小球藻和铜绿微囊藻中叶绿素a的萃取效果。确定了无水乙醇∶90%丙酮（2∶1）的萃取效果最好，而无水乙醇从效果、安全、环保等角度考虑为最优溶剂。通过多参数水质监测仪对不同时间段的浅水型湖库水体中的叶绿素a进行监测，验证了在超声条件下无水乙醇测定结果的准确性并利用正交实验确定出了无水乙醇萃取叶绿素a的最佳条件。对于叶绿素a测定的优化研究使得以后野外水体大量测量叶绿素a的过程变得更为简便、快捷、准确。     

Reduction of formaldehyde emission from plywood

The aim of this work is to evaluate performances of tannin-based resins designed as adhesive in the plywood production. For this purpose, a part of phenol formaldehyde (PF) and melamine formaldehyde (MF) in the classic adhesive formulation was replaced by tannin. The physical properties of the formulated resins (rheological characterization, etc.) were measured. In order to analyze the mechanical performance of tannin-based resins, plywood panels were produced and the mechanical properties including tensile strength wood failure and three-point bending strength were investigated. The performance of these panels is comparable to those of plywood panels made by commercial PF and MF. The results showed that the plywood panels bonded with tannin–PF (PFT) and tannin–MF (MFT) resins exhibited better mechanical properties in comparison to the plywood panels made of commercials PF and MF. The introduction of small properties of tannin in PF and MF resins contribute to the improvement of the water performance of these adhesives. The formaldehyde emission levels obtained from panels bonded with tannin-based resins were lower than those obtained from panels bonded with control PF and MF. Although there are no actual reaction at all between PF, MF, and tannin, addition of tannin significantly improves the water resistance of PF and MF resins. This is a novel finding that manifests the possibility of replacing a convention PF and MF resins by tannin. Modified adhesive is one of the goals in the plywood production without changing any of their production conditions with improvement to their overall properties.     

环氧树脂固化促进剂的微胶囊化及其应用

本文用原位聚合法制备了环氧树脂固化促进剂的徽胶囊,并在环氧胶带中使用。将非水溶性2-乙基-4-甲基咪唑(EMI)预反应物在水中分散,然后使三聚氰胺一甲醛预聚物在其表面原位聚合制取徽胶囊．测定了EMI预反应物在徽胶囊中的含量及其与制备过程中EMI与MF预聚物用量的关系。将此胶囊用于环氧胶带的制备。所得胶带储存性能和外观良好,且徽胶囊对胶带固化有较好促进作用。     

Indirect Determination of Water in Nitroglycerin-Nitrocellulose Pastes by gas-liquid chromatography

A gas-liquid chromatographic procedure was developed in connection with the determination of water in nitroglycerin-nitrocellulose pastes. The method is based on the reaction of water with 2,2-dimethoxypropane and its conversion to acetone which is subsequently determined. The technique is simple, rapid, and shows good accuracy and precision. A simplified method, which is less accurate but does not involve chromatography, is also proposed.     

溶剂对顺丁烯二酸酐含量测定的影响

顺丁烯二酸酐是一种重要的有机原料,对其含量的测定有很大意义.目前,文献上提到的顺丁烯二酸酐含量测定方法的误差较大.因此,研究了各种条件下测定顺丁烯二酸酐的含量.实验结果表明:用纯水、40 % DMF水溶液或40 %丙酮水溶液做溶剂时,都能够较准确测定顺丁烯二酸酐的含量,在有机体系中用40 %丙酮水溶液较纯水或40 %DMF水溶液好.     

非诺贝特酸的相转移催化合成

以4-羟基-4＇-氯二苯甲酮和氯仿为原料,TEBA为催化剂,在氢氧化钾水溶液存在的条件下合成了非诺贝特酸。考察了氢氧化钾溶液浓度、催化剂用量、滴加氯仿温度和氯仿用量等因素对非诺贝特酸产率的影响。确定最佳反应条件为：4-羟基-4＇-氯二苯甲酮30 g,丙酮120 g,氯仿40 g,TEBA 2.5 g,氢氧化钾水溶液浓度50%,反应温度30℃,产率可达89.7%。     

Study on ketalization reaction of polyvinylalcohol by ketones. III. Reaction between polyvinylalcohol and methyl ethyl ketone and behavior of polyvinylketal in water

Ketalization reaction of polyvinylalcohol (PVA) by methyl ethyl ketone (MEK), dimethyl-sulfoxide (DMSO) as solvent, under the presence of acidic catalyst, in homogeneous system was carried out, and the synthesis of polyvinylketal with any ketalization degree was successfully performed. The reaction mechanism of PVA with MEK is identical with that with acetone: for both cases, the equilibrium constant is ca. 0.07 at 40°C and the heat of reaction is 7.5 kcal/mol. Films prepared from the polyvinylketal were soaked in water and degree of swell, solubility, and hydrolysis of films were measured. The reaction of film with water, in acidic side, easily proceeds, and at first the film swells; then, as deketalization reaction proceeds, the film dissolves in water. With polyvinylketal of the ketalization degree of above 15 mol %, dissolution time is controlled by both ketalization degree and pH of water, which reveals that deketalization reaction proceed proportionally to proton concentration at 37°C. On the other hand, in the neutral condition where hydrolysis does not proceed at all, polyvinylketal of ketalization degree of 10–40 mol % dissolves in water at 0°C. The polyvinylketal obtained by MEK is more stable in water than that from acetone since MEK has hydrophobicity.     

Fabrication of Gelatin/Chitosan Microspheres with Different Morphologies and Study on Biological Properties

Gelatin/Chitosan (Gel/Cs) microspheres were prepared by emulsion-coagulation method using glutaraldehyde as cross-linker. The influence of treatment methods, including removing water by different concentration of acetone/water solution and freeze-drying, on surface morphology was investigated, and the biological properties, such as cell cytotoxicity and hemolytic test, were also studied. The experimental results indicated that collapsed and aggregative, wrinkled and smooth Gel/Cs microspheres was obtained when treated by pure acetone, acetone/water solution (volume ratio of 7:1) and acetone/water solution (volume ratio of 3:1), respectively. The microspheres with porous structure were prepared when the obtained smooth Gel/Cs microspheres were treated by freeze-drying method. The cytotoxicity test result demonstrated that no significant cytotoxicity of the Gel/Cs microspheres against L929 mouse fibroblasts was observed. The hemolytic test suggested that the Gel/Cs microspheres, with a hemolytic index of 1.03%, did not have an obvious hemolytic reaction.     

Synthesis of spherical NiO nanoparticles using a solvothermal treatment with acetone solvent

Nanometer-sized nickel oxide (NiO) particles were synthesized by thermal reactions with nickel (II) carbonate as a metal-containing precursor and four solvents: water, ethanol, butanol, and acetone. The optimal reaction conditions to obtain spherical NiO were determined to be the acetone solvent, nickel carbonate precursor, and a reaction temperature and time of 200 °C and 48 h, respectively. TEM images revealed perfectly spherical NiO nanoparticles of size ranging from 2.0 to 10.0 nm in the acetone solvent. The reaction mechanism for the formation of the NiO nanoparticles is proposed based on a pathway of chelated Ni complex during crystal growth. Although metallic Ni was also formed from reactions using the two alcoholic solvents, the Ni(OH)₂ structure remained in the water solvent after thermal treatment.     

Lipase-Catalysed Synthesis of Fatty Acid Modified Chitobiose in a Low-Water Organic Solvent: Effect of Water Distribution in a Multiphase Reaction System

Lipase-catalysed condensation of chitobiose and myristic acid in low-water acetone media was investigated. A product identified as monomyristoyl chitobiose was obtained using immobilized lipase B from Candida antarctica (Novozym 435). The product yield was significantly affected by reaction conditions, such as the initial water concentration in acetone, the initial water content of immobilized lipases, and the amount of added molecular sieves. The product yield varied in the range 0–10%. The effects of the reaction conditions are discussed in relation to the quantitative distribution of water in the reaction system, that is, water adsorbed onto immobilized enzymes, water adsorbed onto molecular sieves, and free water dissolved in the organic solvent.     

Preparation and characterization of melamine–formaldehyde–DTPA chelating resin and its use as an adsorbent for heavy metals removal from wastewater

Melamine–formaldehyde–diethylenetriaminepentaacetic acid (MF–DTPA) resin was prepared as a new adsorbent for removing heavy metals from wastewater effluents. The resin was synthesised by anchoring the chelating agent diethylenetriaminepentaacetic acid (DTPA) to melamine via amide covalent bond during melamine–formaldehyde condensation reaction in an acidic aqueous medium. The effects of reaction parameters (temperature, acidity, and water content) on resin characteristics (water regain, rigidity, DTPA functionality, and porosity) were monitored to specify the best synthesis conditions. The resin was chemically characterized using infrared spectroscopy (FTIR), elemental analysis (EA), thermal programmed decomposition-mass spectrometry (TPD-MS), solid-state ¹³C NMR and ¹⁵N NMR, and was morphologically characterized using N₂ gas adsorption/desorption (BET analysis) and field emission-scanning electron microscopy (FE-SEM). The water regain factor was also calculated to determine hydrophilic character of the resin. The simultaneous adsorption performance of MF–DTPA resin towards selected heavy metals, Co(II), Cd(II), Zn(II), and Cu(II), was discussed. Quantitative analysis for adsorption was conducted using atomic absorption to investigate the kinetics, adsorption isotherm and thermodynamics of the removal process considering pH, initial concentration, temperature, and contact time as controlling parameters. The mechanism of adsorption was suggested based on experimental results. This work shows the potential application of the MF–DTPA resin for removing heavy metals from wastewaters.     

Influence of Co‐Solvent Concentration on the Properties of Dope Solution and Performance of Polyethersulfone Membranes

Polyethersulfone (PES) dope solutions were prepared from mixtures of two solvents containing N,N‐dimethylformamide (DMF) as core solvent and acetone as co‐solvent (CS) in a closed heating system. PES asymmetric membranes were cast by a dry/wet phase inversion process. Complete miscibility of PES with the fixed mixture of acetone and DMF under atmospheric pressure could be achieved. The kinetic and thermodynamic properties indicated that interaction of DMF and acetone is strongest when their mole ratio is unity, pointing to the phenomenon of true co‐solvency for PES dissolution. These results were supported by determination of the water uptake, contact angle measurement, and SEM analyses. Membrane performance, pore volume, and total pore volume on the membrane surface were also investigated.     

CuO/SiO_2催化剂用于CO_2加氢合成甲醇的研究

采用等容浸渍法 ,分别以水、乙醇、丙酮为分散剂制备 Cu O/ Si O2 催化剂 ,用 H2 - TPR,H2 - TPD技术及 CO2 加氢合成甲醇反应对催化剂还原性能、H2 吸附性能和催化性能进行了研究 .TPR结果表明 ,以水为分散剂制备催化剂时 ,Cu O分散不均匀 ,且难还原 ;以丙酮为分散剂时 ,Cu O分散较均匀 ,且易还原 ;以乙醇为分散剂时 ,Cu O的分散性和还原性介于水与丙酮制得的催化剂之间 .TPD结果表明 ,以乙醇、丙酮为分散剂制备催化剂时 ,只增加 H2 的吸附量 ,而不改变 H2的吸附强度 . CO2 加氢反应的结果表明 ,以乙醇和丙酮做分散剂 ,有利于 CO2 转化率、甲醇产率的提高 ,同时降低了反应的甲烷化 .随 Cu O含量增加 ,CO2 的转化率和甲醇的产率得到了提高 .