相转移催化氧化法合成2－乙基己酸的研究

相转移催化氧化法合成２－乙基己酸的研究成本诚，王淳（中南工业大学化学系，长沙４１００８３）２－乙基己酸俗称异辛酸，主要用以制取各种酯类和盐类，广泛用于涂料、塑料、橡胶、医药及军事工业。２－乙基己酸的合成大多以２－乙基己醇为原料，常用的高价无机氧化剂有...     

聚6-羟基己酸碱性条件下的水解反应研究

探究了碱性条件下聚6-羟基己酸水解反应的机理和最优化工艺条件。实验过程中选用碱度较大的氢氧化钠及碱度较小的碳酸氢钠作为反应试剂。研究表明:碱度不同,其反应机理,反应工艺条件亦不同。碱度越大,OH~-浓度越大,亲核基团[OH~-]直接进攻聚6-羟基己酸的酯基结构,使酯基键发生断裂反应,生成小分子的6-羟基己酸;反应工艺条件缓和,在100℃的集热式恒温加热磁力搅拌器中既可完全解聚。碱度大的氢氧化钠参与反应的最优化工艺条件:氢氧化钠/聚6-羟基己酸摩尔比为4.4,乙二醇/聚6-羟基己酸摩尔比为6.5,水用量100g,催化剂0.1g,反应时间2h,反应温度100℃条件下,6-羟基己酸产率达到84.07%;碱度小的碳酸氢钠钠参与反应的最优化工艺条件:碱度越小,OH~-浓度越小,在反应初期亲核基团[-OCH_2CH_2OH]占主导地位,发生醇解反应的概率大,整个反应体系为醇解反应与水解反应相互促进进行;反应工艺条件苛刻,须在180℃密闭高压釜中完全解聚。碳酸氢钠/聚6-羟基己酸摩尔比为1.1,乙二醇/聚6-羟基己酸摩尔比为3,水用量100g,催化剂0.1g,反应时间1h,反应温度180℃~190℃条件下,6-羟基己酸产率达到90.38%。在整个反应系统中,乙二醇作为溶剂来使用。     

用固体超强酸SO_4~(2－)／TiO_2催化剂合成N，N－二乙氨基乙醇己酸酯

在固体超强酸ＴｉＯ＿２催化剂存在下，己酸２与Ｎ，Ｎ－二乙氨基乙醇３直接酯化合成了相应的己酸酯１。在溶剂甲苯中，２与３于１２０～１７０℃下反应４小时，己酸酯１的产率最高达９２．３％。     

光谱法研究氨基己酸与牛血清白蛋白的相互作用

利用荧光光谱、紫外-可见吸收光谱及圆二色（CD）光谱研究了模拟生理条件下的氨基己酸(ACA)与牛血清白蛋白(BSA)的相互作用。 实验结果分析表明,氨基己酸对BSA的内源性荧光具有猝灭作用,属于动态猝灭过程。 计算了2种温度下ACA-BSA体系的结合常数、结合位点数及反应的热力学参数ΔG、ΔH和ΔS分别约为-21.00 kJ/mol、-0.64 kJ/mol和-72.00 kJ/(mol·K),由此推出了二者主要通过氢键和范德华力形成摩尔比为1∶1的复合物。 依据Forster非辐射能量转移理论求得二者之间的结合距离为2.3 nm。 位点取代实验指出氨基己酸主要结合在位点Site I。 CD光谱表明,氨基己酸诱导了BSA分子二级结构微变。     

直接进样-气相色谱法分析发酵液中的脂肪酸

在酒醅中加入己酸发酵液进行混合发酵是提高白酒风味的有效措施之一。其加入量需根据发酵液中己酸含量而定。这就需要准确地测定发酵液中各酸的含量。 测定脂肪酸的方法很多,一般有比色法,柱色谱法,纸色谱法及目前常用的气相色谱法。比色法只能测单个酸,不能测定混合酸。柱色谱法和纸色谱法分离时间长,试剂用量大,准确度低,重现性差。气相色谱法分析脂肪酸一般采用衍生化法,其中包括甲酯化法、乙酯化法、丁酯化法和苄酯化法,对于己酸发酵     

用固体超强酸SO^2—4／TiO2催化剂合成N,N—二乙氨基乙醇己酸酯

在固体超强酸ＳＯ２＾２－４／ＴｉＯ２催化剂存在下，己酸２与Ｎ，Ｎ－二氨基乙醇３直接酯化合成了相应的己酸酯１。在溶剂甲苯中，２与３于１２０－１７０℃下反应４小时，己酸酯１的产率最高达９２．３％。     

光学纯（4S，5R）－4－甲基－5－羟基－3－羰基己酸特丁酯的化学酶促合成

采用化学方法合成了4－甲基－3，5－二羰基己酸特丁酯。以Lactobacillus brevis醇脱氢醇为生物催化剂，选择性地将4－甲基－3，5－二羰基己酸特丁酯还 原为（4S，5R）－4－甲基－5－羟基－3－羰基己酸特丁酯（99．2％ ce,sym: anti=97:3)。     

硫酸氢钠催化合成己酸异戊酯的研究

己酸异戊酯是应用最广泛的食用香料之一。通常它是在硫酸催化下由己酸和异戊醇酯化反应而得[1] ,硫酸虽然活性高 ,价廉 ,但选择性差 ,产品质量不好 ,设备腐蚀严重 ,同时产生大量废液 ,污染环境。已发现对甲苯磺酸、磺酸树脂、固体超酸、杂多酸、氯化铁以及过渡金属硫酸盐等均可作为酯化反应的优良催化剂[2～ 7] 。本文探讨了硫酸氢钠催化羧酸的酯化反应 ,结果发现它具有良好的催化性能 ,且后处理方便 ,无污染。1　实验部分在装有分水器、温度计和回流冷凝器的四颈烧瓶中 ,加入一定量分析纯的己酸、异戊醇、甲苯和催化剂硫酸氢钠 (ＮａＨＳＯ…     

乌龙茶“铁观音”香气成分的气相色谱/质谱分析

以HP-20M（50m×0.2mm×0.2μm）毛细管柱为分离柱,GC/MSD分析中国乌龙茶“铁观音”的香气成分,结果表明,“铁观音”茶的香气主成分为沉香醇及其氧化物、苯甲醛、3-己烯醇己酸酯、3-甲基丁酸、α-萜品醇、水杨酸甲酯、己酸、牛儿醇、苯甲醇、苯乙醇、苯乙腈、顺-茉莉酮、4-甲基-3-乙基吡咯、β-紫罗酮、橙花叔醇、癸醇己酸酯、顺-法呢醇和吲哚等。     

脂肪酸丙烯醇酯的合成

用乙酸、丙酸、丁酸、戊酸、己酸分别与丙烯醇在加热下通过无水硫酸铜,进行反应,得到了乙酸丙烯酯、丙酸丙烯酯、丁酸丙烯酯、戊酸丙烯酯、己酸丙烯酯,其产率分别为60%,75%,74.2%,70%,72%.     

Infrared spectroscopy studies of the cyclic anhydride as the intermediate for the ester crosslinking of cotton cellulose by polycarboxylic acids. I. Identification of the cyclic anhydride intermediate

The mechanism of esterification of cotton cellulose by a polycarboxylic acid was investigated using Fourier transform infrared spectroscopy (FT-IR). The infrared spectroscopic data indicate that a polycarboxylic acid esterifies with cotton cellulose through the formation of an acid anhydride intermediate. A five-member cyclic anhydride intermediate was identified in the cotton fabric treated with poly(maleic acid). The five-member cyclic anhydride is a reactive intermediate and readily esterifies when reaction sites are available. We also found that those polycarboxylic acids, which form five-member cyclic anhydride intermediates, crosslink cotton cellulose more effectively than those polycarboxylic acids which form six-member cyclic anhydride intermediates. © 1993 John Wiley & Sons, Inc.     

Bi-acylation of cellulose: determining the relative reactivities of the acetyl and fatty-acyl moieties

The global reaction between acetic anhydride and a fatty acid yields, at equilibrium, an asymmetric acetic-aliphatic anhydride in a medium containing finally: acetic-fatty anhydride, acetic anhydride, fatty acid, acetic acid and fatty anhydride. No solvent or catalyst was used to evaluate the impact of the actual reactivity of the anhydrides. The competition between the formation of acetyl and fatty acyl ester functions was evaluated by determining the ratio of acetyl/fatty acyl groups grafted on solid cellulose. The influence of temperature, reaction time, and length of fatty chain on the total degree of substitution and on the ratio of acetyl/fatty acyl ester functions was investigated. For the first time, a correlation has been established between esterification and the length of the aliphatic chain of the fatty acid. Reactivity of the medium decreased with the number of carbons in the fatty acid, raised to the power 2.37.     

Preparation of poly(glycidylmethacrylate‐divinylbenzene) weak acid cation exchange stationary phases with succinic anhydride,phthalic anhydride,and maleic anhydride for ion chromatography

In this work, poly(glycidylmethacrylate‐divinylbenzene) microspheres were prepared and applied for the preparation of weak acid cation exchange stationary phases. Succinic anhydride, phthalic anhydride, and maleic anhydride were selected as carboxylation reagents to prepare three weak acid cation exchangers by direct chemical derivatization reaction without solvent or catalyst. The diameters and dispersity of the microspheres were characterized by scanning electron microscopy; the amount of accessible epoxy groups and mechanical stability were also measured. The weak acid cation exchangers were characterized by Fourier transform infrared spectroscopy; the content of carboxyl groups was measured by traditional acid base titration method. The chromatographic properties were characterized and compared by separating alkali, alkaline earth metal ions and ammonium and polar amines. The separation properties enhanced in the order of succinic anhydride, phthalic anhydride, and maleic anhydride modified poly(glycidylmethacrylate‐divinylbenzene) cation exchangers.     

FT-IR and FT-raman spectroscopy study of the cyclic anhydride intermediates for the esterification of cellulose: III. Cyclic anhydrides formed by the isomers of cyclohexanedicarboxylic acid

Multifunctional carboxylic acids have been used as crosslinking agents for cotton and wood pulp cellulose. In our previous research, we found that a polycarboxylic acid esterifies cellulose through the formation of a 5-membered cyclic anhydride intermediate by the dehydration of two carboxyl groups. In this research, we studied the formation of cyclic anhydride intermediates by different isomers of cyclohexanedicarboxylic acid (CHA) so that we can elucidate the effects of molecular structure on the formation of the anhydride intermediates. We found that both cis-and trans-1,2-CHA form 5-membered anhydride intermediates when temperature reaches their melting points and that cis-1,2-CHA forms the cyclic anhydride at temperatures lower than does trans-1,2-CHA. 1,3-CHA forms 6-membered cyclic anhydride at temperatures much higher than its melting point. The formation of a 5-membered cyclic anhydride intermediates takes place at temperatures lower than that of a 6-membered anhydride. This is probably the main reason why those polycarboxylic acids with their carboxylic acid groups bonded to the adjacent carbons of the molecular backbones are more effective crosslinking agents for cellulose than those with their carboxylic groups bonded to the alternative carbons. No formation of cyclic anhydride was found for 1,4-CHA. The formation of a five-membered cyclic anhydride was accelerated by monosodium phosphate, which is used as a catalyst for the esterification of cotton cellulose by polycarboxylic acids.     

Highly powerful and practical acylation of alcohols with acid anhydride catalyzed by Bi(OTf)(3).

Bi(OTf)(3)-catalyzed acylation of alcohols with acid anhydride was evaluated in comparison with other acylation methods. The Bi(OTf)(3)/acid anhydride protocol was so powerful that sterically demanding or tertiary alcohols could be acylated smoothly. Less reactive acylation reagents such as benzoic and pivalic anhydride are also activated by this catalysis. In these cases, a new technology was developed in order to overcome difficulty in separation of the acylated product from the remaining acylating reagent: methanolysis of the unreacted anhydride into easily separable methyl ester realized quite easy separation of the desired acylation product. The Bi(OTf)(3)/acid anhydride protocol was applicable to a wide spectrum of alcohols bearing various functionalities. Acid-labile THP- or TBS-protected alcohol, furfuryl alcohol, and geraniol could be acylated as well as base-labile alcohols. Even acylation of functionalized tertiary alcohols was effected at room temperature.     

Thermal degradation of polymethacrylic acid

The thermal degradation of polymethacrylic acid was found to have two separate decomposition regions. The first decomposition region, due to anhydride formation primarily, was caused by the conversion of polymethacrylic acid to polymethacrylic anhydride. This reaction followed first-order kinetics and had an activation energy of 40.5 kcal/mol. The second decomposition region was the thermal degradation for the corresponding polymethacrylic anhydride. In this region, the fragmentation of anhydride rings structure in polymethacrylic anhydride constitutes the major decomposition reaction with an activation energy of 37.4 kcal/mol. © 1992 John Wiley & Sons, Inc.     

Surface grafting of polymers onto inorganic ultrafine particles: Reaction of functional polymers with acid anhydride groups introduced onto inorganic ultrafine particles

The surface grafting onto inorganic ultrafine particles, such as silica, titanium oxide, and ferrite, by the reaction of acid anhydride groups on the surfaces with functional polymers having hydroxyl and amino groups was examined. The introduction of acid anhydride groups onto inorganic ultrafine particle was achieved by the reaction of hydroxyl groups on these surfaces with 4-trimethoxysilyltetrahydrophthalic anhydride in toluene. The amount of acid anhydride groups introduced onto the surface of ultrafine silica, titanium oxide, and ferrite was determined to be 0.96, 0.47, and 0.31 mmol/g, respectively, by elemental analysis. Functional polymers having terminal hydroxyl or amino groups, such as diol-type poly(propylene glycol) (PPG), and diamine-type polydimethylsiloxane (SDA), reacted with acid anhydride groups on these ultrafine particles to give polymer-grafted ultrafine particles: PPG and SDA were considered to be grafted onto these surfaces with ester and amide bond, respectively. The percentage of grafting increased with increasing acid anhydride group content of the surface: the percentage of grafting of SDA (M_n = 3.9 × 10³) onto silica, titanium oxide, and ferrite reaching 64.7, 33.7, and 24.1%, respectively. These polymer-grafted ultrafine particles gave a stable colloidal dispersion in organic solvents.     

Catalytic actions of alkaline salts in reactions between 1,2,3,4-butanetetracarboxylic acid and cellulose: I. Anhydride formation

1,2,3,4-Butanetetracarboxylic acid (BTCA) reacts with cellulose in two steps: anhydride formation of adjacent carboxyl groups in BTCA and esterification of anhydride with cellulose, which are generally catalyzed by alkaline salts including sodium hypophosphite. The role of the salts in the reactions has been unclear. As an effort in fully understanding the catalytic effects of the salts, reaction mechanisms of alkaline metal ions and acid anions of the salts were investigated in details in the reactions. In this research, functions of alkaline metal ions on the formation of anhydride were studied. Results indicated that the existence of lithium, sodium or potassium promoted the formation of anhydride, and potassium ion was the most efficient one among these three ions. Besides, the reactions of a BTCA molecule with cellulose undergo a step-by-step process, i.e. formation of one anhydride and esterification of the anhydride with cellulose, and then formation of another anhydride and esterification of it to establish cross-linking by the BTCA.     

Synthesis of Poly(Adipic Anhydride) by Use of Ketene

Polyadipic anhydrides were prepared (a) from the mixed anhydride of adipic acid and acetic acid, (b) from the mixed anhydride of adipic acid and ketene in tetrahydrofurane solution (0°C), (c) by melt polycondensation of adipic acid with ketene, and (d) from the seven-membered ring adipic anhydride. The polymers were characterized by means of NMR, IR, DSC, and GPC. The polymer with the highest melting temperature was obtained by melt polycondensation of adipic acid with ketene (T _peak 76°C). The heat of fusion was approximately 40 J/g in all four methods. The number-average and weight-average molecular weights of the polyanhydrides were 2000 and 3000, respectively.     

GC-MS法用于苯二甲酸酐催化氯化过程的研究

将ＧＣ－ＭＳ用于以氯磺酸为介质（在Ｆｅ和Ｉ２存在的情况下）苯二甲酸酐催化氯化合成四氯苯酐的反应过程研究,对反应物中间体产物（一,二,三氯苯二甲酸酐及异构体）进行了定性和相对百分含量分析,找出了提高收率的最佳工艺条件。