1,2:5,6-二-O-异亚丙基-D-甘露醇合成工艺及应用

1,2:5,6-二-O-异亚丙基-D-甘露醇是合成具有重要生理活性天然产物的一种重要手性合成子。文中概述了1,2:5,6-二-O-异亚丙基-D-甘露醇国内外合成及应用、市场概况,重点介绍目前开发新合成工艺的进展及其特点。该新工艺具有原料来源丰富、反应时间短、工艺条件温和及易于实现工业化生产的特点。     

（R）-2-氨基-3-甲基-3-烯-丁酸甲酯的合成研究

以D-甘露醇为起始原料,经8步反应合成了具有光学活性的α-氨基酸前体-（R）-2-氨基-3-甲基-3-烯-丁酸甲酯,总收率为10．15％,e．e值为82％,其中,最具关键性和新颖性的步骤是通过Overman重排反应形成C—N键。     

四硝酸甘露醇酯类化合物的合成和抑菌活性

以海藻中提取的海洋活性物质D-甘露醇为原料,先与丙酮发生缩合反应,将1,2,5,6位的羟基保护起来,再对3,4位的羟基分别甲醚化、甲基磺酸和对甲苯磺酸酯化后,脱去异亚丙基保护基团,还原1,2,5,6位的羟基,并对其进行硝酸酯化,合成了3个标题化合物,产率在77%以上。合成的部分中间体和目标产物的结构,经红外光谱(IR)、核磁共振氢谱(1HNMR)、碳谱(13CNMR)、质谱(MS)和元素分析进行了确证。抑菌实验表明,这3个1,2,5,6-四-O-硝酸甘露醇酯类化合物具有一定的选择性,仅对金黄色葡萄球菌(G Staphylococcus aureus)有抑制作用,最小抑制浓度为50μg/mL,抑制作用没有太大的差别。     

球孢虫草(CCordycepa bassiana)活性威分分析

以球孢虫草为材料,采用气相色谱测定了虫草多糖的单糖组成,高碘酸钠比色法测定了D-甘露醇含量,应用HPLC测定了核苷类物质的含量及组成,并与野生冬虫夏草进行了比较.结果表明,球孢虫草胞外多糖(EPS)由甘露糖和半乳糖组成,摩尔比是1.2:1.0;胞内多糖(IPS)由甘露糖、半乳糖和葡萄糖组成,摩尔比为5.4:4.0:1.0.球孢虫草子座与发酵菌丝体中甘露醇的含量分别为4.01%和12.05%;且它们中均含有鸟苷、腺苷和尿苷三种成分,但发酵菌丝体中三者的含量高于子座及野生冬虫夏草.通过三种活性成分测定,为综合评价球孢虫草内在品质和开发球孢虫草提供了科学依据.     

Transient natural convection heat transfer of liquid D-mannitol on a horizontal cylinder

Transient and steady state natural convection heat transfer for D-mannitol on a horizontal cylinder was investigated experimentally at various liquid temperatures and heat input conditions. To clarify the natural convection phenomena of D-mannitol, transient and steady heat transfer coefficients were measured under various liquid temperatures of D-mannitol and periods of heat generation rates from a horizontal platinum cylinder. The platinum cylinder with a diameter of 1 mm and a length of 43.5 mm was used as the test heater in this experiment. Experimental results indicated that the steady heat transfer coefficient of D-mannitol was affected by the liquid temperature. As the liquid temperature increased, it was understood that the effect of liquid temperature weakened. When the period of the heat generation rate was changed, the heat transfer process was divided into natural convection heat transfer and conductive heat transfer. It was considered that the conductive heat transfer was more dominant as the period of the heat generation rate decreased. The empirical correlations of steady and transient heat transfer coefficients for D-mannitol were obtained.     

1,2,5,6-双异亚丙基-D-甘露醇的合成与表征

以D-甘露醇为起始原料,在氯化亚锡的催化下使用了2,2-二甲氧基丙烷,对1,2以及5,6位羟基进行保护,提高了羟基保护的选择,合成1,2,5,6-双异亚丙基-D-甘露醇。结果表明最佳反应条件为:D-甘露醇与2,2-二甲氧基丙烷摩尔比为1∶3.0,无水氯化亚锡与D-甘露醇摩尔比1∶200,反应时间1h,收率为92.0%。用IR与1HNMR对其结构进行了表征。     

Polymorphism of D-mannitol: Crystal structure and the crystal growth mechanism

The polymorphism of D-Mannitol(mannitol) is reviewed in this paper. It was found that the structure of the stable form is consistent in most literatures, but different authors have given different information about the two metastable forms. Therefore the commonly used nomenclature of mannitol was summarized based on the crystal unit cell parameters with the help of X-ray powder diffraction. Moreover, the crystal growth mechanism of mannitol polymorphs was summarized. Considering the lack of kinetic data for the metastable form especially, a reported method was attempted to apply to δ mannitol in an aqueous cooling crystallization process based on the induction time previously measured, and it was identified that the growth of the δ form follows the two-dimensional(2D) nucleationmediated mechanism. The results also indicate that the method based on induction time and supersaturation should have the potential to be expanded to the metastable polymorphs for the growth property study in a bulk system.     

氯化锌催化合成二异亚丙基-D-甘露醇

以甘露醇为原料,氯化锌作催化剂合成二异亚丙基-D-甘露醇,考察了影响反应的因素,结果表明反应的最佳条件为:n(D-甘露醇)∶n(丙酮)∶n(氯化锌)=1∶21·4∶1·85,反应温度为30~35℃,反应时间12h,产率可达62·8%。     

IMO/D-甘露醇水溶液玻璃化转变温度的确定及冻干过程塌陷现象分析

采用冻干显微镜和差示扫描量热法(DSC)研究了溶液的塌陷温度Tc和热历史特性,将两种测量结果相结合确定冷冻浓缩状态下的玻璃化转化温度Tg',分析不同升降温速率对低聚异麦芽糖(IMO)溶液Tg'及Tc的影响,根据D-甘露醇反玻璃化和强化冰晶结构的特性,研究其对IMO溶液Tg'和Tc的影响.结果 表明:溶液的热历史存在低温...