三氯蔗糖的合成方法

本文综述了强力甜味剂三氯蔗糖的主要合成方法。参考文献14篇。     

蔗糖聚合物

蔗糖是自然界中分布最广的二糖 ,其价格低、纯度高、可再生 ,以其作为原料可以得到许多特殊的化学和生物产品。本文综述了蔗糖聚合物的最新研究发展 ,介绍了不同蔗糖聚合物的制备途径以及它在医药、生物等领域的应用。     

柱色谱分离蔗糖酰化产物中蔗糖-6-乙酸酯的研究

通过蔗糖C-6位羟基的选择性乙酰化反应,合成的蔗糖-6-乙酸酯是进一步制备卤代蔗糖衍生物的重要中间体[1]。三氯蔗糖是目前被广泛关注的一种新型卤代蔗糖衍生物[2],它是以天然的蔗糖为原料,经半化学合成而得到的强力甜味剂,具有高甜度、低热值、无毒和抗龋齿等特点。在众多的三氯蔗糖的合成方法中[3-5],必须首先要对活泼的蔗糖C-6位羟基进行保护,即蔗糖的选择性酰化反应。蔗糖的乙酰化产物中除蔗糖-6-乙酸酯外,还有未转化的原料蔗糖和部分反应副产物。因此,为了减轻后续工艺合成的难度,降低制备成本,使最终产物三氯蔗糖容易提纯,必须对酰化…     

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].     

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。     

蔗糖测定的紫外分光光度新方法研究及应用

方法基于在酸性条件下,蔗糖水解生成果糖和葡萄糖,果糖受热破坏后,其产物在285nm处有较大的紫外吸收。通过试验,确定了最佳条件,并建立了测定蔗糖的新紫外分光光度法;其线性范围为0.27～31.2μg/mL,摩尔吸光系数ε为9.63×103L·mol-1·cm-1。该法简单、快速,准确度高,用于甘蔗汁中蔗糖含量的测定,结果满意。对蔗糖水解的机理进行了初步探讨。     

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.     

蔗糖的化学

蔗糖既是食品,又是化工原料。本文以甘蔗糖发展的3个阶段(煎蔗提糖、甘蔗化工、蔗糖加工)为主要线索,概略地阐述蔗糖化学的演进过程。通过分析蔗糖的分子结构,指出蔗糖的化学或生物加工的可能途径和相应产品,并简介蔗糖与人类的密切关系。     

辛酸蔗糖酯的超声合成和表征

研究了超声技术促进蔗糖的酯化反应,考察了反应温度、时间、催化剂等对反应的影响．当蔗糖与辛酸乙酯的摩尔比为2：1,反应温度为70℃,催化剂K2CO3占辛酸乙酯质量分数的11％和反应压力为11kPa的条件下,超声反应2h,能高产率地获得辛酸蔗糖酯,且产物的单酯化物含量达92％．产物结构用红外和核磁表征,产物易溶于极性溶剂,热稳定性好,亲水亲油平衡值（HLB）为10．8．     

蔗糖酯的薄层分析

 以硅胶G板为固定相、甲苯 乙酸乙酯 甲醇 水 (体积比为 1 0∶5∶4 5∶0 2 )为流动相 ,研究建立了蔗糖酯薄层分析方法。在蔗糖酯上行展开后 ,用脲 磷酸 水饱和正丁醇溶液显色 ,斑点呈蓝色 ,蔗糖单酯的Rf 值为 0 1 6 ,多酯的Rf 值为 0 38～ 0 93。在 70℃显色 2 0min的最佳条件下 ,蔗糖单酯的检测量为 2 5 μg～ 2 50 μg时 ,其斑点面积与其检测量有良好的线性关系。用归一法和外标法对该分析方法的准确度进行考察和认证 ,两种方法对已知单酯含量的S 1 570样品测定结果的t 检验结果分别为 |t| =0 62 7(<2 571 )和 |t|=1 1 2 3(<2 571 ) 。     

瓜儿豆胶和刺槐豆胶抑制阿斯巴甜甜感强度的机制探索

目前大分子水溶胶对于味觉物质的影响机制研究主要集中于胶体自身的性质以及胶体结构与味物质的相互作用.本文选择了食品中常用的瓜儿豆胶(GG)和刺槐豆胶(LBG),研究了这两种非离子水溶胶对甜味剂阿斯巴甜(APM)感官甜度的影响,并探索了其中的物理化学机制.感官实验结果表明,高浓度的瓜儿豆胶和刺槐豆胶对阿斯巴甜的甜度有抑制作用,且随着水溶胶浓度的增高,达到高分子临界交叠浓度C*后,抑制作用更明显.基于人工受体模型,利用等温滴定量热(ITC)技术发现,两种水溶胶存在条件下阿斯巴甜与受体模型相互作用的结合常数急剧减小.另外,通过对甜味剂存在下非离子水溶胶的水分分布、扩散性质的考察,发现随水溶胶浓度增加,体系的结合水含量均增多,尤其是水溶胶浓度达到临界交叠浓度(C*)后增多的现象更明显;同时,分子的扩散也受到了阻碍,从而导致阿斯巴甜感官甜度的降低.本研究表明,探索大分子水溶胶对甜味剂分子与受体结合差异性的影响、溶液中水分子的弛豫性质及赋存状态、结合体系的粘度及扩散性质的研究,为理解大分子水溶胶对甜味影响的物理化学机制提供更多的信息.     

环糊精对阿斯巴甜的甜感增强作用及二者相互作用热力学

目前环糊精（CD）对阿斯巴甜（ASP）甜感强度的影响研究主要集中在环糊精对阿斯巴甜的稳定性研究。我们认为CD对ASP甜感强度的提升与其和ASP的结合常数有一定的关系。本文选择了五种环糊精,α-环糊精（α-CD）、β-环糊精（β-CD）、γ-环糊精（γ-CD）、羟丙基-β-环糊精（HP-β-CD）、甲基-β-环糊精（Met-β-CD）,研究了这些环糊精存在下ASP的感官甜度的变化及二者的相互作用。结果表明,β-CD可以明显提升ASP的甜感强度。等温滴定量热（ITC）和荧光光谱对ASP与CDs结合过程亲和力的研究表明,ASP与β-CD的结合是自发的,并且具有最大的结合常数。差示扫描量热（DSC）、核磁共振（¹H NMR）以及傅里叶变换红外（FT-IR）揭示了其结合过程的机制。本研究对理解甜味剂甜感强度与热力学结合常数的关系具有重要的意义,也为基于结合常数筛选风味保持剂的方法提供有益的基础。     

Solubilization of steviolbioside and steviolmonoside with gamma-cyclodextrin and its application to selective syntheses of better sweet glycosides from stevioside and rubusoside

1,4-alpha-Glucosylation at the 13-O-glycosyl moiety of stevioside (S) and rubusoside (RU) results in a significant increase of sweetness. Saponification of the 19-COO-beta-glucosyl linkage of S and RU yielded steviolbioside (SB) (= 13-O-beta-sophorosyl-steviol) and steviolmonoside (SM) (= 13-O-beta-glucosyl-steviol), respectively, both of which are poorly soluble in an acetate buffer. It was found that the solubilities of SM and SB in the buffer solution were remarkably increased in the presence of gamma-cyclodextrin (gamma-CD). SB was solubilized in the buffer solution with the aid of gamma-CD, and the solution was subjected to 1,4-alpha-transglucosylation by using a cyclodextrin glucanotransferase-starch system to give a mixture of products which were glucosylated at the 13-O-glycosyl moiety. This mixture was acetylated, and the acetate was subjected to chemical beta-glucosylation of 19-COOH followed by deacetylation to afford compounds which have superior sweetness to S. In the same way, derivatives with superior sweetness were selectively prepared from RU through SM.     

Mechanism of atmospheric CO2 fixation in the cavities of a dinuclear cryptate

Using density functional theory (DFT) methods, we have investigated two possible mechanisms for atmospheric CO(2) fixation in the cavity of the dinuclear zinc(II) octa-azacryptate, and the subsequent reaction with methanol whereby this latter reaction transforms the (essentially) chemically inert CO(2) into useful products. The first mechanism (I) was proposed by Chen et al. [Chem.-Asian J. 2007, 2, 710], and involves the attachment of one CO(2) molecule onto the hydroxyl-cryptate form, resulting in the formation of a bicarbonate-cryptate species and subsequent reaction with one methanol molecule. In addition, we suggest another mechanism that is initiated via the attachment of a methanol molecule onto one of the Zn-centers, yielding a methoxy-cryptate species. The product is used to activate a CO(2) molecule and generate a methoxycarbonate-cryptate. The energy profiles of both mechanisms were determined, and we conclude that, while both mechanisms are energetically feasible, free energy profiles suggest that the scheme proposed by Chen et al. is most likely.     

Attachment of Pseudomonas putida onto differently structured kaolinite minerals: a combined ATR-FTIR and 1H NMR study

The attachment of Pseudomonas (P.) putida onto well (KGa-1) and poorly (KGa-2) crystallized kaolinite was investigated in this study. Batch experiments were carried out to determine the attachment isotherms of P. putida onto both types of kaolinite particles. The attachment process of P. putida onto KGa-1 and KGa-2 was adequately described by a Langmuir isotherm. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance were employed to study the attachment mechanisms of P. putida. Experimental results indicated that KGa-2 presented higher affinity and attachment capacity than KGa-1. It was shown that electrostatic interactions and clay mineral structural disorders can influence the attachment capacity of clay mineral particles.     

Molecular dynamics simulation of the kinetics of nucleation of supercooled NaCl melt clusters

Approaches to describing the structure of metastable liquids are considered. A criterion for the classification of particles in a supercooled NaCl melt is suggested. The criterion is based on the Q₆ method and structural features of salt crystals. It was applied to analyze the configurations of clusters calculated by the molecular dynamics method. The results were interpreted using classic nucleation theory and the probabilistic approach. It was shown that crystalline phase nuclei with subcritical sizes existed in a metastable liquid. The evolution of nucleus sizes follows a complex mechanism. Along with monomer attachment and detachment reactions, collective structural fluctuations play a noticeable role.     

Evolution of single crystalline dendrites from nanoparticles through oriented attachment

Single crystalline PbMoO4 dendrites were prepared by a simple hydrothermal method in the presence of surfactants. The formation and evolution of these dendrites was investigated by transmission electron microscopy, and the results clearly showed that the dendritic structure was achieved through oriented attachment of nanoparticles along crystallographically specific direction while the traditional Ostwald ripening mechanism also acted to form the initial particles before attachment and smooth the morphology of the dendrites after attachment.