D-异抗坏血酸硬脂酸酯的合成及其性能研究

L-抗坏血酸(VC)高级脂肪酸酯,是一类新型的脂溶性抗氧化剂,被广泛用于油脂、食品、医疗卫生、化妆品等领域。D-异抗坏血酸(即异VC)是L-抗坏血酸的异构体,与L-抗坏血酸相比较,被氧化的速度更快,价格更低,是近年来在国内外得到普遍使用的食品抗氧化剂。但是,由于溶解性的原因,D-异抗坏血酸不能用于动植物油的保鲜。如果也能将高级脂肪酸引入到D-异抗坏血酸分子中生成D-异抗坏血酸高级脂肪酸酯。     

D-异抗坏血酸饱和脂肪酸酯的合成

用浓H2SO4作为反应介质和催化剂,通过直接酯化法或酯交换法合成了5个D-异抗坏血酸脂肪酸(癸酸,月桂酸,豆蔻酸,棕榈酸和硬脂酸)酯,其结构经1H NMR和IR表征.实验结果表明,就粗产物的产率和纯度而言,直接酯化法均比酯交换法高.     

高效液相色谱法同时测定水果蔬菜中L-抗坏血酸、D-异抗坏血酸、脱氢抗坏血酸及总维生素C的含量

建立了同时测定水果或蔬菜中L-抗坏血酸、D-异抗坏血酸、脱氢抗坏血酸及总维生素C含量的高效液相色谱分析方法。用偏磷酸提取水果或蔬菜样品中L-抗坏血酸、D-异抗坏血酸和脱氢抗坏血酸,提取液中的L-抗坏血酸、D-异抗坏血酸可直接进行检测,脱氢抗坏血酸在磷酸钠溶液中(p H 7.0~7.2)用L-半胱氨酸还原成L-抗坏血酸,之后测定以L-抗坏血酸表达总维生素C含量,脱氢抗坏血酸含量由总维生素C含量减去L-抗坏血酸含量获得。采用C18色谱柱分离,以甲醇-磷酸盐缓冲溶液(p H 3.5)为流动相,在245 nm下检测,外标法定量。结果表明,在0.5~50 mg/L的浓度范围内L-抗坏血酸和D-异抗坏血酸的线性关系良好,相关系数大于0.999,检出限分别为42.0,19.4μg/kg,脱氢抗坏血酸的检出限为262μg/kg。低、中、高3个浓度的加标水平下,3种物质的加标回收率为82.8%~111.3%,相对标准偏差(RSD)小于15%。该方法操作简单,灵敏度高,准确性好,适用于水果和蔬菜中维生素C的测定。     

脂肪酶催化合成L-抗坏血酸脂肪酸酯和D-异抗坏血酸脂肪酸酯

用固定化脂肪酶Lipozyme 435作催化剂,分别用直接酯化法和酯交换法合成L-抗坏血酸脂肪酸酯和D-异抗坏血酸脂肪酸酯.产物结构经IR、1HNMR、13CNMR和MS表征.结果表明,对于同一目标化合物,相似条件下,直接酯化法的效果优于酯交换法,原料脂肪酸和脂肪酸甲酯均可回收循环使用.     

高效液相色谱法测定毛樱桃中维生素C含量

建立了高效液相色谱(HPLC)测定毛樱桃中维生素C的主要成分L-抗坏血酸和D-异抗坏血酸的方法. 以0.05 mol/L磷酸溶液∶甲醇(体积比为98∶2)作为流动相,紫外检测波长245 nm,柱温25 ℃,流速0.70 mL/min. 获得L-抗坏血酸、D-异抗坏血酸标准曲线线性较好(r为1.0),精密度(RSD)为0.6%. L-抗坏血酸加标回收率为90.83%~92.52%,D-异抗坏血酸加标回收率为91.93%~92.99%. 试验结果表明,方法测定维生素C操作简单、提取速度快、灵敏度高、回收率好,测得L-抗坏血酸的含量为8.24 mg/100 g,D-异抗坏血酸未检测出. 方法可适用于检测其他与毛樱桃相似的果蔬中L-抗坏血酸、D-异抗坏血酸的含量.     

HILIC色谱柱拆分抗坏血酸对映体及其在药物分析中的应用

采用HILIC色谱柱,利用高效液相色谱分离L-抗坏血酸和D-异抗坏血酸,考察了流动相的组成、柱温和流速对分离L-抗坏血酸和D-异抗坏血酸的影响.结果表明:流动相为乙腈-0.1%磷酸(93∶7),流速为0.8 m L·min~(-1),柱温为20℃,检测波长为243 nm的条件下,分离效果最优,分离度为7.79.该方法进一步应用于3种维生素C实际样品中抗坏血酸含量的测定,3种样品中均仅有L-抗坏血酸检出,其含量在96.62~985.8 mg·g~(-1)之间,相对标准偏差在0.65%~0.94%之间.     

新型1′-碘代炔丙基糖苷类化合物的合成及其抗菌活性

以四种单糖(D-葡萄糖、D-半乳糖、D-甘露糖和D-核糖)为原料,先在酸催化下与炔丙醇完成糖苷化反应(产率60%～80%);然后在碱催化下碘代合成了四个新型1′-碘代炔丙基糖苷类化合物(3a～3d,产率75%～90%),其结构经1H NMR表征.初步生物活性测试结果表明,3对引起农作物疾病的几种真菌均有抑制活性.     

亲水作用色谱法同时测定食品添加剂中D-异抗坏血酸、L-抗坏血酸和二氧化硫脲

食品添加剂样品用含1%(体积分数,下同)甲酸的100mmol·L~(-1)甲酸铵溶液溶解,经乙腈稀释后,用0.22μm微孔滤膜过滤,采用亲水作用色谱法同时测定滤液中D-异抗坏血酸、L-抗坏血酸和二氧化硫脲的含量。以InfinityLab Poroshell 120HILIC-Z色谱柱(3.0mm×100mm,2.7μm)为固定相,以含1%甲酸的100mmol·L~(-1)甲酸铵溶液和乙腈以体积比15∶85组成的混合液为流动相,用二极管阵列检测器测定。D-异抗坏血酸、L-抗坏血酸和二氧化硫脲的质量浓度均在1.0～100mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)均为1.0%。以空白样品为基体进行加标回收试验,所得回收率为94.7%～108%,测定值的相对标准偏差(n=6)小于8.0%。     

新型单硼酸衍生物的合成及作为荧光探针对糖的选择性识别

合成了一种新的单硼酸衍生物,分别考察了其与D-葡萄糖、D-果糖、D-甘露糖的结合反应,通过硼酸衍生物荧光强度变化达到对糖的选择性识别.该化合物合成简单,作为糖的荧光探针,选择性好,生物基质中的氨基酸、蛋白质和生物胺均不干扰糖的测定.测定上述3种糖时,其浓度分别在0.01～1.0 μmol·L-1,0.1～2.0 μmol·L-1和0.2～3.0 μmol·L-1范围内,与荧光强度呈现良好的线性关系.方法具有较高的灵敏度,不同糖的检出限在0.008 2～0.10 μmol·L-1之间.应用于人血清中D-葡萄糖浓度的测定,结果满意.     

新型取代苯甲胺葡萄糖氮苷的合成及其抗缺氧活性

以取代苯甲醛(1a~1s)为原料,通过三条路线［A:1a~1o为起始原料,经硼氢化钠还原和溴代反应制得苄基溴衍生物(3a~3o); 3a~3f与邻苯丁二酰亚胺经Gabriel反应制得N-苯甲基邻苯丁二酰亚胺衍生物(4a~4f); 4a~4f与水合肼反应后与D-吡喃葡萄糖反应合成了N-β-D吡喃葡萄糖苯甲胺类化合物(6a~6f)。 B: 3g~3o与全乙酰化D-吡喃葡萄糖胺反应制得全乙酰化葡萄糖氮苷5g~5o; 5g~5o在MeONa-MeOH中脱除乙酰基合成了6g~6o。 C: 1p~1s与全乙酰化D-吡喃葡萄糖胺反应制得全乙酰化葡萄糖氮苷5p~5s; 5p~5s经MeONa-MeOH脱除乙酰基合成了6p~6s］合成了19个取代苯甲胺N-β-D吡喃葡萄糖氮苷类似物(6a~6s,其中6a, 6b, 6e, 6f, 6j, 6n~6q, 6s为新化合物),其结构经¹H NMR和ESI-MS表征。采用MTT法研究了6a~6s对缺氧内皮细胞代谢活力的影响。结果表明： 6a, 6g, 6h和6l的抗缺氧活性优于红景天苷。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。