杂多酸催化剂在有机合成中的应用

介绍了杂多酸催化剂在Friedel-Crafts酰基化和烷基化反应、Diels-Alder反应、酯化反应、环缩合反应、重排反应、溴化反应、氧化反应及不对称催化反应等有机合成反应中的应用。展望了该领域未来的研究方向。     

离子液体在有机合成中的应用新进展

室温下的离子液体作为一种绿色、环保、可替代传统有机溶剂的新型溶剂受到了极大关注.总结了近年来离子液体在有机合成反应中的研究新进展,包括氧化反应、还原反应、Friedel-Crafts反应、Diels-Alder反应、Heck反应、硝化反应及其它合成反应.     

聚合物反应挤出技术

叙述了聚合物反应挤出的定义、优缺点、反应挤出设备及反应挤出的原理等;阐述了反应挤出的应用,并展望了反应挤出的发展趋势。     

择形催化剂上α-蒎烯异构化反应动力学研究

用择形催化剂ＸＣ－９０催化α－蒎烯异构化反应,考察了反应时间、反应温度对反应结果的影响,研究了该反应的动力学,求出了反应的表观活化能、频率因子和反应级数,建立了反应速率常数与温度的关系式     

脂肪酶催化碳-碳键形成反应的研究

脂肪酶的多功能性广泛应用于有机合成反应中.本文综述了脂肪酶催化碳-碳键形成反应进展,例如:Michael反应、Mannich反应、Knoevenagel反应、Diels-alder反应、Henry反应等.     

欢迎订阅《药物中间体化学(第2版)》

<正>《药物中间体化学(第2版)》在第1版的基础上,以中间体为主线,在加强理论知识的同时,详细介绍了包括药物中间体合成设计、环合反应、硝化反应、磺化反应、酰化反应、加成反应、氧化反应、还原反应、缩合反应、氨解反应、烷基化反应、卤化反应、手性药物中间体合成以及药物中间体的分离与结构鉴定等内容,并重点介绍了化合物的新型合成方法与检测手     

基于链段法的PBT聚合反应体系建模及工艺流程模拟

基于链段法定义了对苯二甲酸和1,4-丁二醇聚合生成聚对苯二甲酸丁二醇酯(PBT)的反应体系的各组分和基团,明确了体系中的反应类型有酯化反应、酯交换反应、酯基降解反应、1,3-丁二烯生成反应、四氢呋喃生成反应,通过链段浓度表示了各个反应的反应速率及聚合物性质,并采用Aspen Polymer工艺流程模拟软件建立了PBT三...     

水煤浆加压气化合成氨装置CO变换反应设计

分析了C0变换反应反应热效应、化学平衡常数及反应动力学;对影响C0变换反应平衡的因素如温度、压力、催化剂、水气比等进行了讨论。介绍了采用Aspen Plus模拟软件中RK-S0AVE状态方程、平衡反应模块(REquil)的C0变换反应模拟计算,供变换反应的相关工程设计人员参考。     

吲哚-3-甲醛合成的研究进展

综述了国内外吲哚-3-甲醛的传统合成方法,包括Reimer-Tiemann反应、吲哚盐与酰氯的反应、Duff反应、Rieche反应、Friedel-Craftsacylations反应和Vilsmeier-Haack反应,并分析了其中存在的问题。同时介绍了近几年来在合成吲哚-3-甲醛方法中的进展。     

分子内还原Heck反应合成7-溴-1-茚满酮

研究了标题化合物的合成新方法,即以邻溴苯甲酸为原料,经取代反应、氧化还原反应、格氏反应以及分子内还原Heck反应合成了目标化合物。探讨了分子内还原Heck反应中反应溶剂、反应温度、反应时间及催化剂种类等条件对产率的影响。最终确定了以四氢呋喃为溶剂、Pd(dppf)Cl_2为催化剂、60℃反应6 h的最佳反应条件,产率可达83%。     

纤维素氨基甲酸酯的合成研究进展

纤维素氨基甲酸酯(CC)是一种再生纤维素产品,被视为黏胶工艺中纤维素磺酸酯最有潜力的替代产品。对CC的发展过程、研究现状、合成方法和应用性能进行介绍,对酯化反应中所使用的纤维素溶剂进行分类和总结,并详细介绍离子液体作为无副产物纤维素溶剂的研究进展。     

Solubility of bacterial cellulose and its structural properties

Based on experiments conducted, it has been found that bacterial cellulose, like spruce cellulose, is soluble in an aqueous NaOH solution with the concentration of 8.5% at a temperature of −5°C if the polymerization degree of the cellulose does not exceed 400. When 1% of urea is added to the NaOH solution, the solubility of cellulose increases; and, in this solvent, bacterial cellulose may be dissolved so long as its polymerization degree is below 560. The results of these experiments are of great practical importance since they point to the possibility of the preparation of cellulose spinning solutions suitable for fiber formation. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1871–1876, 1998     

Derivatization of cellulose in lithium chloride and N-N-dimethylacetamide solutions

The derivatization of cellulose in mixtures of lithium chloride and N,N-dimethylacetamide (LiCl/DMAc) is described. A wide range of cellulose derivatives, including cellulose esters, carbamates, sulphonates and ethers, have been synthesized in homogeneous solution using the LiCl/DMAc solvent. In most cases, a high degree of substitution was achieved, and the degree of substitution could be controlled accurately. Compared to current heterogeneous synthesis of cellulose derivatives, reactions conducted in homogeneous solutions of LiCl/DMAc have many advantages: (1) reactions may be conducted at moderate temperatures; (2) less reagent is required; (3) less degradation of the cellulose occurs; and (4) substitution is uniformly controllable.     

A novel,efficient procedure for acylation of cellulose under homogeneous solution conditions

Commercially available cellulose (Avicel PH101) was successfully acylated under homogeneous solution conditions by the following novel procedure: 2.0 g of cellulose and 5.0 g of LiCl were introduced into a glass reactor, magnetic stirring was started, the pressure was reduced to 2 mmHg, the temperature was raised to 110°C in 30 min, and the reactor was kept under these conditions for another 30 min. N,N‐Dimethylacetamide, 60 mL, was introduced, atmospheric pressure was restored, and the temperature was raised to 150°C in 30 min. The system was kept under these conditions for 1 h, then the temperature was decreased to 40°C; in 2 h a clear cellulose solution was obtained. Acid anhydride was added, and the solution was stirred at 60°C for additional 18 h. Acetates, propionates, butyrates, and acetate/butyrate mixed ester were prepared with excellent reproducibility of the degree of substitution, from 1 to 3. The degree of polymerization of cellulose is negligibly affected by these reaction conditions. The distribution of the acetyl moiety among the three OH groups of the anhydroglucose unit follows the order C₆ > C₂ > C₃. Features relevant to the industrial application of this novel procedure are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1355–1360, 1999     

纤维素及其主要衍生物接枝改性的研究进展

纤维素是自然界大量存在的可再生高分子材料,是理想的环境友好材料,但是纤维素本身结构复杂,难溶、难融,使其应用受到限制。利用接枝共聚的方法改性纤维素,使其能部分或完全取代石油基塑料将极具前景。本文综述了近年来纤维素、二醋酸纤维素、乙基纤维素接枝改性的进展,并对今后的研究方向进行了展望。     

Ozone treatment for improving the solubility of cellulose extracted from palm fiber

We investigated effects of ozone treatment on solubility of cellulose and chemical composition in cellulose extracted from palm fiber. The initial holocellulose, α-cellulose, and lignin contents of the extracted cellulose were 88.0, 81.9, and 8.75%, respectively. The extracted cellulose was treated with ozone and NaOH solution. Ozone treatment for 5 hr at 40°C using 3% citric acid decreased the lignin content from 8.75 to 2.71%. Under these conditions, the degree of polymerization (DP) of the cellulose decreased to 29 from 160 and the carboxyl content increased to 2.05 mmol/g. When the solid phase was treated with NaOH after ozone treatment, the mass of the solid phase decreased as the ozone treatment time increased. The lowest mass was 0.43 g. Additionally, the mass of cellulose regenerated from the liquid phase increased with increasing treatment time. The highest mass of regenerated cellulose was 0.54 g. The masses of the solid phase and regenerated cellulose obtained without ozone treatment under the same conditions were 0.76 and 0.18 g, respectively. These results suggest that ozone treatment improves the solubility of cellulose by converting hydroxyl groups in the cellulose to carboxyl groups and reducing the DP.     

氧化纤维素的制备研究

介绍了氧化纤维素 (DAC)的制备过程 ,用正交法探讨了以NaIO4 作氧化纤维素时反应温度、溶液pH值、氧化剂浓度、反应时间以及交互作用对DAC醛基含量的影响 ,找到了影响醛基含量的主要因素为反应温度、反应温度与NaIO4 的交互作用、反应温度与溶液 pH值的交互作用。初步确定了制备氧化纤维素的反应工艺 ,使醛基含量较高时的最佳反应条件为 :反应温度 3 5℃ ,反应时间 3h ,NaIO4 质量分数 6.78% ,pH值为 2时 ,醛基含量达 68.2 0 %。     

Effect of the agitation rate on the generation of low-crystallinity cellulose from phosphoric acid

Changes in the basic powder properties of low-crystallinity powder cellulose (LCPC) as a function of the agitation rate used during its generation from phosphoric acid were investigated. We reacted cotton linter with phosphoric acid (85% w/v) at room temperature for an hour and then at 50°C for 3 h to produce the LCPC solution. The latter was slowly added to water (ca. 10 times the volume of phosphoric acid used) at a constant agitation rate of 700, 2000, or 4000 rpm. LCPC powder thus formed was collected by filtration, washed with water and acetone, and dried at 30°C. Scanning electron micrographs showed the three products to be highly aggregated in structure. The crystallinities of LCPC prepared at 700, 2000, and 4000 rpm were 39, 31, and 24%, respectively. The crystalline component of LCPC produced at 700 and 2000 rpm contained both cellulose II (major component) and cellulose I (minor component), whereas LCPC generated at 4000 rpm belonged to the cellulose II crystal lattice. The porosity and true, bulk, and tap densities of LCPC made at 4000 rpm were 88.55% and 1.435, 0.138, and 0.164 g/cc, respectively. The corresponding values for LCPC made at 700 and 2000 rpm were 60.30% and 1.452, 0.541, and 0.576 g/cc and 54.49% and 1.465, 0.583, and 0.667 g/cc, respectively. Avicel® PH-101, in contrast, had a degree of crystallinity of 89% and a true density value of 1.577 g/cc. The porosity, bulk density, and tap density values were intermediate to those of LCPC made at 4000 rpm and 700 or 2000 rpm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2624–2628, 2001     

Melt spinning of thermotropic cellulose derivatives

The melt spinning of two thermotropic cellulose derivatives—trimethyl silyl cellulose and phenyl acetoxy cellulose—is described in this article. Removal of the substituents was facile, rapid, and essentially complete. Both the melt‐spun and regenerated fibers had banded textures typical of fibers spun from a liquid crystalline phase. The regenerated cellulose fibers had high strengths and moduli compared to viscose rayon and Lyocel cellulose fibers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 418–423, 2000     

醋酸丙酸纤维素的合成研究进展

综述了醋酸丙酸纤维素的合成研究现状和发展趋势,其中包括醋酸丙酸纤维素的均相反应和非均相反应的合成方法,探讨了各种反应的的优势及CAP应用前景。