TiSiW12O40/TiO2催化合成乙酸环己酯

以固载杂多酸TiSiWl2O40／TiO2催化乙酸和环己醇合成了乙酸环己酯。实验确定最佳反应条件为：n(乙酸)：n(环己醇)=1．0：1．1，TiSiW12O40／TiO2用量为乙酸质量的5％，反应时间1．5h，酯化率达95．5％。     

Pd-SiW12/SiO2催化剂上乙烯直接氧化制乙酸的反应机理

 利用积分反应器和微分反应器对Pd－SiW12／SiO2催化剂上乙烯直接氧化生成乙酸的反应机理进行了探讨．乙烯在积分反应中氧化的主要产物为乙酸（选择性为77．6％），很少生成乙醛（选择性仅为8．1％）；而在微分反应中氧化的主要产物是乙醛（选择性为98．4％）．在微分反应中分别以乙醛和乙醇为主反应物时，乙醛氧化完全生成乙酸，选择性为100％，而乙醇氧化生成乙酸的选择性低于0．15％．可以认为，在Pd－SiW12／SiO2催化剂上，水蒸气存在下乙烯主要经由中间物乙醛而生成乙酸．通过对含有不同组分和不同还原条件处理的催化剂活性的比较，认为目的反应主要发生在Pd与SiW12相互接触的部位，催化剂中的Pd0是活性Pd物种的主要形态．     

离子抑制色谱法同时测定化学镀液中的四种有机酸

HP1100型高效液相色谱仪,配G1316A二极管阵列检测器,HP Chemstation化学工作站（美国安捷伦公司）。有机酸标准品：乙酸、柠檬酸为分析纯,纯度大于99％（西安化学试剂厂）;乳酸为分析纯,纯度为85％（天津市化学试剂六厂,需标定）;氨基乙酸为生化试剂,纯度大于99％（广东汕头市红卫化工厂）。磷酸二氢钠、磷酸为分析纯（西安化学试剂厂）。     

2-噻吩乙酸的合成

以噻吩为原料,经乙酰基反应、氧化重排生成2-噻吩乙酸甲酯(2),2经水解得2-噻吩乙酸(3),总收率53．0％,其结构经IR和^1H NMR确证。     

高效液相色谱法测定乌梅有机酸

采用Kromnsil C18为分析柱,0．0lmol／L磷酸盐缓冲溶液(pH2．7)为流动相,紫外215nm检测,建立了乌梅中草酸、酒石酸、苹果酸、乳酸、乙酸、柠檬酸、琥珀酸等多种有机酸的高效液相色谱方法。方法的回收率为98％～105％;RSD为2．26％～7．82％;检出限为10～75ng(S／N=3)。测定了4种不同产地和种类的乌梅中的苹果酸、乳酸、乙酸、柠檬酸、琥珀酸的含量。     

气相色谱/质谱法测定卷烟烟气中的主要挥发酸

以异丙醇为溶剂,壬醇为内标,采用气相色谱／质谱法定性定量分析了卷烟烟气中的游离态甲酸和乙酸,还测定了该方法的精密度和准确度,结果为：RSD小于2％,回收率大于97％．     

稀土固体超强酸SO4^2—／TiO2／Ce（Ⅳ）催化合成乙酸正丁酯

以SO4^2-/TiO2/Ce(Ⅳ)为催化剂，乙酸和正丁醇为原料合成了乙酸正丁酯，在n(醇)：n(酸)＝1．4，催化剂0．5g(乙酸200mmol时)，反应时间1．5h的优化反应条件下，酯化率在96％以上。     

丁酸壳聚糖液晶的临界行为研究

用偏光显微镜法测定了丁酸壳聚糖在四种酸性溶剂中的临界浓度值．发现临界浓度值（ｖ／ｖ％）与溶剂的酸性无关，都是１６％～１７％．在以二氯乙酸为溶剂时，不同丁酰化程度的丁酸壳聚糖有相同的临界浓度．用ＤＳＣ法测定了丁酸壳聚糖／二氯乙酸体系的临界温度，并绘制了相图．结果表明，浓度达６０％（ｗ／ｗ％）后，临界温度基本不再变化，稳定在３９℃左右．     

磺化聚氯乙烯的催化酯化作用

聚氯乙烯与氯磺酸反应合成了一种高分子催化剂,研究了它对羧酸和醇的酯化反应的催化活性,探讨了催化合成乙酸正丁酯的反应条件,并催化合成了乙酸、丙酸和丁酸的十一种酯,收率为82—92％。     

功能化离子液体室温催化合成乙酸苄酯

制备了N-甲基-N′-磺酸烷基-咪唑阴离子型功能化室温离子液体,研究了功能化室温离子液体(TSILs)于室温下催化乙酸和苯甲醇反应合成乙酸苄酯的新方法,考察了多种TSILs的催化性能。结果表明,所合成的TSILs具有很高的催化活性,乙酸和苯甲醇的摩尔比为1:1．3,在室温下反应2．5 h,乙酸苄酯的产率可达92％,选择性超过99％。由于生成的乙酸苄酯不溶于催化体系,反应产物与催化体系分层,通过简单的倾析便可实现产物分离,简化了分离过程。离子液体可以循环使用,而其催化活性没有明显降低。     

Improved two-step hydrothermal process for acetic acid production from carbohydrate biomass

An improved two-step process for converting carbohydrate biomass to acetic acid under hydrothermal conditions is proposed. The first step consists of the production of lactic acid from carbohydrate biomass, and the second step consists of conversion of the lactic acid obtained in the first step to acetic acid using CuO as an oxidant. The results indicated that CuO as an oxidant in the second step can significantly improve the production of high-purity acetic acid from lactic acid, and the maximum yield of acetic acid was 61%, with a purity of 90%. The yield of acetic acid obtained using the improved two-step hydrothermal process from carbohydrate biomass, such as glucose, cellulose and starch, was greater than that obtained using traditional two-step process with H2O2 orO2. In addition, a proposed pathway for the production of acetic acid from lactic acid in the second step with CuO was also discussed. The present study provides a useful two-step process for the production of acetic acid from carbohydrate biomass.     

活性炭负载硅钨酸催化合成乙酸正丁酯

以活性炭负载硅钨酸为催化剂,乙酸和正丁醇为原料合成乙酸正丁酯.优化的反应条件如下:在冰乙酸0.253mol、正丁醇0.22mol、催化剂用量为反应物总量的1.5%(质量分数)、反应温度115℃,反应时间为90min的条件下,酯化率可达97.8%.产品纯度>98%,并且催化剂可以多次使用活性没有明显下降.     

Potassium permanganate/carboxylic acid/organic solvent: a powerful reagent for enone oxidation and aryl coupling reactions

The α′-acetoxylation of enones and the α-acetoxylation of aromatic ketones were carried out with potassium permanganate and acetic acid, in which acetoxylation products were obtained in 74-96% yields. The same reaction was carried out with carboxylic acids other than acetic acid, which furnished corresponding acyloxy ketones with the same regioselectivity. For the first time, formyloxylation products were synthesized in a 61-85% yield by using formic acid. The potassium permanganate and acetic acid method was also used for aryl coupling reactions. The reaction of arylboronic acids and arylhydrazines in benzene with potassium permanganate and acetic acid in turn furnished biaryls in 85-96% yield. We have shown that potassium permanganate/carboxylic acid/organic solvent behaves as manganese(III) acetate.     

Sequential injection redox or acid-base titration for determination of ascorbic acid or acetic acid

Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l⁻¹ was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l⁻¹ ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid–base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2–8% w v⁻¹ of acetic acid with a relative standard deviation of 4.8% (5.0% w v⁻¹ acetic acid, n=11) was obtained. Sample throughputs of 60 h⁻¹ were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.     

一锅法合成3-溴丙基乙酸酯

以1，3-丙二醇、氢溴酸（48％）和冰醋酸为原料，在带水剂的作用下，一锅法合成了3-溴丙基乙酸酯．考察了带水剂及追加醋酸或醋酸酐量对产率的影响，并通过气质联用仪对粗产品进行分析测定，推断其反应机理．结果表明：较适宜的合成条件为1，3-丙二醇0．21mol，1，3-丙二醇与氢溴酸（48％）、冰醋酸摩尔比为1：1：1．3，在带水剂甲苯（21mL）的作用下，反应2．5h，反应结束前1h追加4．8mL醋酸酐，合成效果最好，产率可达到95．7％．     

New process for producing cellulose acetate from wood in concentrated acetic acid

To explore further potential applications of acetic acid pulp, an investigation was conducted to develop a direct method for producing cellulose acetate from wood in combination with atmospheric acetic acid pulping. The process consists of delignification, totally chlorine-free bleaching, and esterification, with the concentrated acetic acid aqueous solution being used as only solvent throughout the process. The acetic acid pulp with kappa number of 30 and ISO brightness of 16 was bleached with 5% ozone on pulp to kappa number of 1.4 and brightness of 61. The resulting bleached pulp was further bleached with peracetic acid to kappa number of less than 1.0 and brightness of 68. The final bleached acetic acid pulp was acetylated with acetic anhydride in the concentrated acetic acid for 45 min to produce cellulose acetate with an apparent degree of substitution (DS) of 2.54. Although the product was lower grade compared with commercially available cellulose diacetate because it was prepared from the chemical pulp but not dissolving pulp, the product was almost soluble in acetone. Eventually, the DS of the acetone-soluble fraction was 2.62. The acetone solubility might be attributed to the original acetic acid pulp that had been partially acetylated during the pulping.     

Synthesis of ethyl acetate by esterification of acetic acid with ethanol over a heteropolyacid on montmorillonite K10

In present work, liquid phase esterification of acetic acid with ethanol over dodecatungestophosphoric acid (DTPA) supported on K10 montmorillonite was systematically studied and optimization of process parameters was carried out. The 20% m/m DTPA/K10 was found to be the optimum catalyst with 90% acetic acid conversion and 100% ethyl acetate selectivity. The study was also explored to see the feasibility of 20% m/m DTPA/K10 as a catalyst for the alkylation of acetic acid with other alcohols like methanol, iso-propanol and n-butanol. The 20% m/m DTPA/K10 has shown increased activity with the increase in carbon number, at the same alcohol reflux. The results are novel.     

Production of citronellyl acetate in a fed-batch system using immobilized lipase

Several reports exist in the literature citing the decrease in conversion rates of organic-phase catalytic synthesis reactions when acetic acid is present as a reaction component. This inhibition is thought to result from damage to either the hydration layer-protein interaction or the overall enzyme structure. In this work, the inhibitory effect of acetic acid on lipase enzyme activity was ameliorated by conducting syntheses under acetic acid-limiting conditions in a fed-batch system, resulting in higher product yields. Periodic additions of acetic acid at levels of 40 mM or less gave maximum yields of 65% conversion for the reaction of citronellol and acetic acid to form citronellyl acetate. The enzyme used was a fungal lipase fromMucor miehei, and was immobilized on macroporous synthetic resin (a Novo lipozyme Novo Nordisk, Denmark). These results represent a fourfold improvement over batch runs reported in the literature for direct esterification of terpene alcohol with acetic acid using lipozyme as a catalytic agent.     

A vibrational sum frequency spectroscopy study of the liquid-gas interface of acetic acid-water mixtures: 2. Orientation analysis

Vibrational sum frequency spectroscopy has been used to investigate the surface of aqueous acetic acid solutions. By studying the methyl and carbonyl vibrations with different polarization combinations, an orientation analysis of the acetic acid molecules has been performed in the concentration range 0-100%. The surface tension of acetic acid solutions was also measured in order to obtain the surface concentration. The orientation of the interfacial acetic acid molecules was found to remain essentially constant in an upright position with the methyl group directed toward the gas phase in the whole concentration range. The tilt angle (theta(CH)3) of the symmetry axis of the methyl group with respect to the surface normal was found to be lower than 15 degrees when considering a delta distribution of angles or as narrow as 0 +/- 11 degrees when assuming a Gaussian distribution. Further investigations showed that the C=O bond tilt (theta(C)(=)(O)) of the acetic acid hydrated monomer was constant and close to 55 degrees in the concentration range where it was detected. Finally, the orientation information is discussed in terms of different species of acetic acid, where the formation of a surface layer of acetic acid cyclic dimers is proposed at high acid concentrations.     

Studies on the Ion Exchange Separation of Aspirin,Salicylic Acid and Acetic Acid

The liquid chromatography of aspirin, salicylic acid and acetic acid using cation exchange resins with aqueous alcohol and water as eluent was described. The results indicated that acetic acid could be separated from aspirin and salicylic acid by hydrogen form cation exchange resin with 25% ethanol or water as eluent. The possibility of using this method to determine the degree of hydrolysis of aspirin was discussed.