蔗糖分子中羟基的选择性保护的研究

蔗糖和原乙酸三烷基酯反应后,经三苯甲基化、乙酰化以及乙酰基由4-位到6-位的基团迁移反应,选择性地保护了蔗糖分子中的羟基基团,合成了一系列蔗糖乙酸酯.4,6-原乙酸蔗糖六乙酸酯在酸催化下水解和醇解,相应地得到2,3,6,1',3',4',6'-七-O-乙酰基蔗糖和2,3,1',3',4',6'-六-O-乙酰基蔗糖。这些都是合成蔗糖衍生物方便的中间体,在糖化学的研究中得到应用.     

甜昧剂三氯蔗糖的合成及结构表征

以蔗糖为原料,运用单基团保护法,制备蔗糖-6-乙酯,用Vilsmeier试剂氯代蔗糖-6-乙酯制备三氯蔗糖-6-乙酯,氢氧化钾脱除三氯蔗糖-6-乙酯的乙酰基,制得三氯蔗糖.考察了反应物摩尔比、反应温度、反应时间等对反应的影响.结果表明:蔗糖-6-乙酯的最佳合成条件为n(蔗糖)∶n(原乙酸三乙酯)=1∶2.5,0℃反应4...     

氯代脱氧蔗糖合成的研究

4,6-原乙酸蔗糖六乙酸酯在酸催化下水解和醇解, 选择性地保护了蔗糖分子中的某些羟基, 并通过乙酰基由C~4→C~6迁移的异构化反应合成了一系列蔗糖乙酸酯。利用Vilsmeier试剂作为氯化试剂与蔗糖乙酸酯进行氯化反应, 再除去乙酰基, 合成了六个氯代脱氧蔗糖, 其中的三个由于C~4构型的转换, 为氯代脱氧半乳蔗糖。     

2，3，6，3′，4′-五氧乙酰基蔗糖的合成与表征

以蔗糖为原料通过羟基的选择性保护、脱保护及迁移合成了三氯蔗糖的中间体2,3，6，3’，4’-五氧乙酰基蔗糖（6-PAS）。在蔗糖羟基的选择性保护反应中采用4．二甲氨基吡啶（DMAP）为催化剂，有效地提高了产率．并利用HPLC对选择性脱保护和乙酰基迁移2步反应进行跟踪，确定了较优的合成路线。并用核磁共振和红外光谱对产品进行表征。羟基选择性保护最佳反应条件为：使用质量分数为10％的催化剂，三苯甲基化反应在50℃进行4h，乙酰化反应在105℃进行3h。在该条件下进行反应，产率为81．9％。     

反相高效液相色谱法监测蔗糖-6-乙酸酯合成

4,1′,6′-三氯-4,1′,6′-三脱氧半乳蔗糖(4,1′,6′-Trichloro-4,6′-trideoxygalactosucrose,简称TGS,又称sucralose即蔗糖素)甜度高、低热量、无毒、抗龋。蔗糖-6-乙酸酯(A)是合成三氯蔗糖的重要中间体,其合成路线见图1,本文采用反相高效液相色谱法(RP-HPLC)分析。在选定的色谱条件下,分离效果满意,对其合成工艺有良好的指示作用。     

几种非环单萜衍生物的制备及表征

分别以香叶醇、橙花醇及芳樟醇为原料,经SeO2和t-BuOOH氧化、NaBH4还原得到8-羟基香叶醇、8-羟基橙花醇及8-羟基芳樟醇;利用乙酰化反应和苯甲酰化反应分别制备了这三个二醇化合物的乙酰化和苯甲酰化衍生物;并利用气相色谱-电子电离质谱仪(GC-EIMS)和液相色谱-电喷雾质谱仪(LC-ESIMS)分析了合成产物的光谱性质.结果显示,以GC-EIMS表征合成产物时,除苯甲酰化衍生物呈现较弱的分子离子峰外,其他几个产物均无分子离子峰信号.     

以活性酰化试剂选择性制备蔗糖-6-酯

由于具有良好的表面活性和生物活性,蔗糖-6-酯被广泛应用到表面活性剂、食品添加剂等方面[1,2],它们还是合成超级甜味剂三氯蔗糖的关键中间体[3].     

薄层色谱法在三氯蔗糖合成控制中的应用

本文采用薄层层析法对三氯蔗糖合成过程中所涉及的反应物进行分离分析，通过洗择优化展开体系，有效地分离了蔗糖及其酯类衍生物，并实现了蔗糖乙酸酯同分异构体的分离，较为直观地指示了反应进程。     

N-[3-(4-甲基苯基)-3-氧代-1-芳基丙基]乙酰胺的三氟乙酸催化合成

以对甲基苯乙酮、芳香醛和乙腈为主要原料,通过三氟乙酸催化的改进的Dakin-West反应,顺利得到28个N-[3-(4-甲基苯基)-3-氧代-1-芳基丙基]乙酰胺,最高收率可达95%.18个新化合物的结构经1H NMR,13C NMR和HRMS证实.结构测试发现,羟基苯甲醛参与Dakin-West反应后得到的全部是羟基乙酰化的产物.作者首次证实,羟基苯甲醛参与的Dakin-West反应不是串联反应,而是羟基苯甲醛首先经TFA催化转化为乙酰氧基苯甲醛,然后参与Dakin-West反应,最终生成羟基乙酰化产物.通过碱性水解,可以选择性高收率地制备对应的羟基化β-乙酰氨基酮,同时也反证了羟基乙酰化产物的存在.该研究扩展了TFA催化的Dakin-West反应,为β-乙酰氨基酮的合成提供了新的方法.     

歧化松香蔗糖酯的合成

先将歧化松香与二氯亚砜反应制备歧化松香酰氯,然后与蔗糖发生O-酰化反应合成了歧化松香蔗糖酯。用TLC、IR、13C NMR、UV、HPLC和HPLC-MS等多种方法对目标产物进行了分析和表征,结果显示歧化松香蔗糖单酯是所合成的目标产物中的绝对优势成分,含量可高达96·31%,酯基可能与蔗糖分子中果糖环上的C-1′相接。从目标产物的临界胶束浓度CMC(0·9×10~(-2)mol·L~(-1),此时表面张力σCMC=52·03mN·m~(-1))可知,所制备的歧化松香蔗糖酯具有较好的表面活性。     

离子交换法提纯蔗糖-6-乙酸酯的研究

研究了应用离子交换树脂分离提纯蔗糖－6－乙酸酯的方法，蔗糖－6－乙酸酯的平均回收率为80.06%，平均纯度为90.48%，并用红外光谱、质谱、核磁共振等方法对蔗糖－6－乙酸酯的结构进行了鉴定。     

转Bt基因植物表达产物Cry1Ab蛋白的制备纯化方法研究

以转Bt基因水稻为试材,研究其表达产物Cry1Ab蛋白的提取、分离及纯化的方法。实验结果表明,DEAE-纤维素填料对Bt蛋白有较好捕获效果。根据生物信息学方法预测了目标蛋白和主要共存蛋白的等电点和疏水性差异。合理地选择了阴离子交换色谱与疏水作用色谱组合方法。提取液经DEAE-Sephadex A-50柱层析及Phenyl-Sepharose Fast Flow疏水层析分离后,目标蛋白得到了显著的纯化。考察了疏水层析中用不同洗脱液洗脱Cry1Ab蛋白对活性回收率和纯度的影响,结果表明：以0．25mol／L KSCN作洗脱液对活性影响最小,HIC一步纯化倍数可达8倍,总纯化倍数达100倍。     

微囊化海藻酸离子移变凝胶的制备、结构与性能

通过静电脉冲技术制备了海藻酸-壳聚糖-海藻酸(Alginate-Chitosan-Alginate,ACA)微胶囊,红外光谱分析表明,ACA是一种以聚电解质配合物为囊膜,以海藻酸钠离子吸附剂为囊心物的微胶囊型离子吸附体系.扫描电镜测试表明,ACA吸附重金属离子的过程是微胶囊囊内海藻酸凝胶化的过程,其解吸附过程是海藻酸凝胶转变成海藻酸溶液的过程.与传统离子交换树脂相比,ACA对Pb²⁺的吸附具有较高的去除率、很强的富集能力和较低的极限吸附浓度,并且能够被多次重复使用.ACA的离子交换速率比传统离子交换树脂快得多,离子交换过程中,交换离子和吸附剂海藻酸分子的相互扩散大大提高了离子交换速率.     

离子交换分离钨钼及微波诱导树脂再生的研究

本文研究了不同型号的树脂和硫化条件对离子交换分离钨钼的影响。探讨了用D201树脂交换除钼及其树脂再生的机理。实验结果表明：碱性钨酸铵（AT）溶液经硫化转型后,可用阴离子交换柱除去其微量钼;该除钼树脂经微波场辐照诱导-减性食盐水协同再生处理,可基本恢复其除相交换容量。     

Separation of lithium isotopes by NDOE bonded Merrifield peptide resin

The novel NDOE (1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane) ion exchange resin was prepared. The ion exchange capacity of NDOE azacrown ion exchanger was 0.2 meq/g dry resin. A study on the separation of lithium isotopes was carried out with NDOE novel azacrown ion exchange resin. The lighter isotope,⁶Li concentrated in the solution phase, while the heavier isotope,⁷Li is enriched in the resin phase. By column chromatography (0.1 cm I.D.×32 cm height) using 2.0M NH₄Cl as an eluent, a separation factor,a=1.0201 was obtained.     

Optimization of l‐arginine purification from Corynebacterium crenatum fermentation broth

l ‐Arginine has many special physiological and biochemical functions, with wide applications in the food and pharmaceutical industry. Few studies on the purification of l ‐arginine from fermentation broth have been conducted; however, none of them were systematic enough for industrial scale‐up. Therefore, it is necessary to develop a highly efficient and systematic process for the purification of l ‐arginine from fermentation broth. In this study, we screened out a cation exchange resin, D155, having high exchange capacity, high selectivity, and easy elution capacity, and analyzed its adsorption isotherm, thermodynamics, and kinetics using different models. Further, the process parameters of fixed‐bed ion exchange adsorption and elution were optimized, and the penetration curve during the operation was modeled. Based on the fixed‐bed ion‐exchange parameters, a 30‐column continuous ion‐exchange system was designed, and the flow velocity in each zone was optimized. Finally, to obtain a high purity of l ‐arginine, the purification tests were conducted using anion exchange resin 711, and an l ‐arginine yield of 99.1% and purity of 98.5% was obtained. This effective and economical method also provides a promising strategy for separation of other amino acids from the fermentation broth, which is of great significance to the l ‐arginine fermentation industry.     

高亲水性强阳离子交换色谱填料的制备及其在蛋白质分析中的应用

以具有双孔结构的聚甲基丙烯酸环氧丙酯(PGMA)微球为基质,以葡萄糖进行表面亲水改性,制备了强阳离子交换色谱填料,并将其用于复杂生命体系中生物大分子的快速而高效的分离、分析与纯化。葡萄糖亲水改性增进了填料的生物相容性,提高了蛋白质样品的回收率;双孔结构及较高的比表面积赋予填料良好的柱渗透性和样品负载量。以标准蛋白质为样品,考察了该填料对生物样品的分离性能。以100 mm×4.6 mm的色谱柱分离4种蛋白质,在6 min内实现了基线分离;以溶菌酶为样品,填料的吸附容量为39.5 g/L,在蛋白质快速分离纯化分析中显示了良好的应用前景。     

Preparation, Properties and Mechanism of Inhomogeneous Calcium Alginate Ion Cross-linking Gel Microspheres

Inhomogeneous calcium alginate ion cross-linking gel microspheres,a novel ion absorbent,were prepared by dropping a sodium alginate solution to a calcium chloride solutioin via an electronic droplet generator.Calcium alginate microspheres have uniform particle sizes.a smooth surface and a microporous structure.The electrode probe reveals the inhomogeneous distribution of calcium ions with the highest concentration on the surface,and the lowest concentration in the cores of the spheres.As a novel ion adsorbent,calcium alginate gel microspheres have a lower limiting adsorption mass concentration,a higher enrichment capacity and a higher adsorption capacity for Pb^2 than usual ion exchange resins.The highest percentage of the adsorption is 99.79%.The limiting adsorption mass concentration is 0.0426mg/L.The adsorption capacity for Pb^2 is 644mg/g,Calcium alginate gel microspheres have a much faster ion exchange velocity than D418 chelating resin and D113 polyacrylate resin.The moving boundary model was employed to interpret the ion exchange kinetics process,which indicates that the ion exchange process is controlled by intraparticle diffusion of adsorbable ions.So the formation of inhomogeneous gel microspheres reduces the diffusion distance of adsorbable ions within the spheres and enhances the ion exchange velocity.Alginate has a higher selectivity for pb^2 than for Ca^2 and the selectivity coefficient KCa^Pb is 316. As an ion cross-linking gel,calcium alginate inhomogeneous microspheres can effectively adsorb heavy metal Pb^2 at a higher selectivity and a higher adsorption velocity.It is a novel and good ion adsorbent.     

Separation of lithium isotopes by N4S2 azacrown ion exchanger

The novel N₄S₂ azacrown ion exchange resin was prepared. The ion exchange capacity of N₄S₂ ion exchanger was 0.34 meq/g dry resin. A study on the separation of lithium isotopes was carried out with N₄S₂ azacrown ion exchange resin. The lighter isotope,⁶Li is concentrated in the resin phase, while the heavier isotope,⁷Li is enriched in the solution phase. With column chromatography [0.1 cm (I.D.)×32 cm (height)] using 2.0M NH₄Cl as an eluent, separation factor, a=1.034 was obtained.     

Automated separation and preconcentration of copper(II) from natural waters using a column treatment

Summary A comparison is made between two automated column procedures for the separation and preconcentration of Cu(II) from natural waters. The column materials were: an anion-exchange resin and 8-hydroxyquinoline immobilized on a glass support. 8-Hydroxyquinoline showed about the same performance as the ion exchange resin, but was less time and labour consuming. Cu(II) determinations at the ppb level were checked with standard additions and the results were moreover compared with those obtained by another method.On leave from Lisbon University, Portugal