D-甘露醇与D-山梨醇在纯水和卤化钠水溶液中的稀释焓

应用等温流动微量热技术测定了298.15 K下D-甘露醇和D-山梨醇在纯水和卤化钠水溶液中的稀释焓,利用M cM illan理论计算了D-甘露醇和D-山梨醇在纯水和卤化钠水溶液中焓相互作用系数.结果表明,D-甘露醇和D-山梨醇在纯水和卤化钠水溶液中的二阶焓相互作用系数均为正值,并随着卤离子半径的变化而相应变化;且同种溶剂中,D-甘露醇的二阶焓相互作用系数要大于D-山梨醇的.结合两分子结构的差异,通过溶质-溶质相互作用和溶剂-溶质相互作用对这一结果进行了讨论.     

N,N-二甲基甲酰胺在不同浓度氯化钠水溶液中的稀释过程热力学

应用等温流动微量热法测定了298.15 K时N,N-二甲基甲酰胺(DMF)在纯水及不同浓度氯化钠水溶液中的稀释焓, 根据McMillan-Mayer理论计算得到各级同系焓相互作用系数. 结果表明, DMF在纯水及氯化钠水溶液中的焓对相互作用系数h2均为正值, 并且随着氯化钠浓度的增加, h2的值逐渐增大. 根据溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释.     

肌醇在氯化钠水溶液中的稀释焓和焓对相互作用

应用微量热法测定了298.15K时肌醇在纯水和氯化钠水溶液中的稀释焓,根据McMillan-Mayer理论计算了肌醇在不同浓度的氯化钠溶液中的2到4阶焓相互作用系数.结果表明,肌醇在氯化钠溶液中的焓对相互作用系数h2均为负值,并且随着氯化钠浓度的增大,h2的值呈增大趋势.根据溶质-溶质相互作用和溶质-溶剂相互作用对焓对相互作用系数的变化趋势进行了解释.     

D-山梨醇在纯水和卤化钠水溶液中293.15K～318.15K的稀释焓

应用流动式等温精密微量热技术测定4个温度(293.15、303.15、308.15和318.15 K)下D-山梨醇在纯水和卤化钠水溶液中的稀释焓.根据改进的McMillan-Mayer理论对所测数据进行关联,得到了表观摩尔稀释焓对浓度变化的经验方程和各阶焓相互作用系数(h2,h3和h4)和二阶熵相互作用系数(s2),根...     

丝氨酸在蔗糖水溶液中的稀释焓

利用LKB 2277生物活性检测仪分别测定了298.15 K时丝氨酸在不同组成的蔗糖水溶液中的稀释焓, 利用McMillan-Mayer理论,计算了丝氨酸在不同组成的蔗糖水溶液中的焓对相互作用系数,并与其在葡萄糖水溶液中的焓对相互作用系数h2进行了比较.结果表明,丝氨酸在蔗糖和葡萄糖水溶液中的焓对相互作用系数h2都是负值,并且随着糖浓度的增加,h2系数的绝对值逐渐减少.根据溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释.     

木糖醇在纯水和碱金属卤化物水溶液中的稀释焓

应用等温流动微量热法测定了298.15 K时木糖醇在纯水和碱金属卤化物水溶液中的稀释焓, 根据McMillan- Mayer理论计算了木糖醇在溶液中的二到四阶焓相互作用系数. 结果表明, 木糖醇在碱金属卤盐溶液中的焓对相互作用系数h₂均为正值, h₂值随着碱金属阳离子或卤素阴离子半径的增大皆依次增大. 根据木糖醇参与的溶质-溶质, 溶质-溶剂等弱相互作用, 对该种多元醇在碱金属卤盐水溶液中的焓相互作用系数的变化进行了解释.     

微量热法研究烟酰胺和异烟酰胺在KCl水溶液中的焓对自缔合作用

利用等温滴定微量热法(ITC)分别测定了298.15 K时烟酰胺(NA)和异烟酰胺(INA)在纯水及不同浓度KCl(m=0~0.3 mol/kg)水溶液中的稀释焓,根据McMillan-Mayer理论计算得到相应的焓对自缔合作用系数(h xx),发现两者的h xx都是很大的负值,且在较高KCl浓度时都随KCl浓度的增大而减小.从溶质-溶质、溶质-溶剂相互作用的观点出发,对这2种吡啶羧酸酰胺异构体的疏水和亲水作用平衡进行了讨论:NA和INA都是亲水-亲水作用占优势,芳香性的吡啶环与酰胺基团羰基的π电子共轭使得对位异构体的共振结构分子电荷分离而更具亲水性;吡啶环之间的π-π堆叠对焓对自缔合作用的贡献几乎可忽略;溶液离子强度(I)的增大有利于加强亲水-亲水作用,从而使h xx的绝对值都随溶液中KCl浓度的增大而逐渐增大.     

肌醇在纯水和卤化钠水溶液中稀释过程的热力学性质

应用微量热法测定了298.15 K时肌醇在纯水和卤化钠水溶液中的稀释焓, 根据McMillan-Mayer理论, 计算了肌醇在溶液中的二到四阶焓相互作用系数. 结果表明, 肌醇在卤化钠溶液中的焓对相互作用系数h2均为负值, 并且随着卤素阴离子半径的增大, h2的绝对值呈增大趋势.     

甘氨酸在氯化钾水溶液中的稀释焓

利用瑞典LKB-2277生物活性检测仪测定了298．15K时甘氨酸在不同浓度的氯化钾水溶液中的稀释焓,根据McMilkm-Mayer理论计算了甘氨酸在不同浓度的氯化钾水溶液中的同系焓相互作用系数．结果表明,甘氨酸在氯化钾水溶液中的焓对相互作用系数h2均为负值,并且随着氯化钾浓度的增加,h2的绝对值逐渐减小。     

氨基酸和肽从水到多羟基化合物溶液的迁移焓研究

采用RD-496Ⅱ型精密微量热量计分别测定了甘氨酸、L-丙氨酸、L-丝氨酸、L-苏氨酸、甘氨酰甘氨酸和甘氨酰甘氨酰甘氨酸在纯水以及不同浓度甘露醇、山梨醇和肌醇水溶液中的溶解焓, 计算了这些氨基酸和肽从水到3种多元醇溶液中的迁移焓. 实验发现, 氨基酸和肽从水到多元醇溶液中的迁移焓均为负值, 且随多元醇浓度的增加而减小. 根据共球交盖模型分析了水溶液中氨基酸和肽分子与多元醇分子间的相互作用.     

Concentration effect of sodium chloride on enthalpic interaction coefficients of <Emphasis Type="Italic">D</Emphasis>-mannitol and <Emphasis Type="Italic">D</Emphasis>-sorbitol in aqueous solution

The dilution enthalpies of D-mannitol and D-sorbitol in aqueous sodium chloride solution at various concentrations have been determined by isothermal microcalorimetry at 298.15 K. The homogeneous enthalpic interaction coefficients over a quite large range of concentration of aqueous sodium chloride solutions have been calculated according to the excess enthalpy concept. The results show that enthalpic pairwise interaction coefficients (h ₂) of D-mannitol and D-sorbitol are positive in aqueous sodium chloride solution and become more positive with increase of the concentration of sodium chloride. The results are interpreted in terms of the different conformations of the two polyols, solute-solute and solute-solvent interactions involved by solvent effects.     

Enthalpic interactions of N-glycylglycine with xylitol in aqueous sodium chloride and potassium chloride solutions at T = 298.15 K

The mixing enthalpies of N-glycylglycine with xylitol and their respective enthalpies of dilution in aqueous sodium chloride and potassium chloride solutions have been determined by using flow-mix isothermal microcalorimetry at the temperature of 298.15 K. These experimental results have been used to determine the heterotactic enthalpic interaction coefficients (h_xy, h_xxy, and h_xyy) according to the McMillan–Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients h_xy between N-glycylglycine and xylitol in aqueous sodium chloride and potassium chloride solutions are negative and become less negative with an increase in the molality of sodium chloride or potassium chloride. The results are discussed in terms of solute–solute and solute–solvent interactions.     

甲酰胺与肌醇在氯化钠水溶液中的焓相互作用

应用等温流动微量热法测定298.15 K时甲酰胺与肌醇分子在不同浓度氯化钠水溶液中的混合过程焓变及其稀释焓, 根据McMillan-Mayer理论关联得到各级异系焓相互作用系数(h_xy, h_xxy及h_xyy). 结果表明, 甲酰胺与肌醇分子在氯化钠水溶液中的异系焓对相互作用系数h_xy均为负值, 并且随着氯化钠浓度的增加, h_xy的绝对值逐渐减小.     

Synthesis and study of polyol borates as corrosion inhibitors for steel and nonferrous metals

Interaction of sodium tetraborate with polyols, D-sorbitol and D-mannitol, in aqueous solutions was studied using the method of isomolar solutions, combined with polarimetry and conductometry. The possibility of synthesizing sodium sorbitol borate and mannitol borate with a 1: 1 component ratio was examined. The compounds obtained were tested as corrosion inhibitors for steel, copper, aluminum, and brass in an aqueous medium.     

Liquid chromatographic determination of sugar alcohols in beverages and foods after nitrobenzoylation

Use of p-nitrobenzoyl chloride (PNBC) to form an ultraviolet-absorbing derivative was attempted to determine the sugar alcohols meso-erythritol, xylitol, D-sorbitol, and D-mannitol by liquid chromatography (LC). LC determination of derivatives was performed on an ODS column with acetonitrile-water (65 + 35) as mobile phase. Calibration curves were linear in the concentration range 0.01-100 micrograms/mL. Method sensitivity is 10 to 1000 times higher than that of LC with refractive index detection and gas chromatography with flame ionization detection. Recoveries of sugars added to various foods at 0.1 and 1% ranged from 91 to 102% for meso-erythritol, 75 to 115% for xylitol, 81 to 105% for D-sorbitol, and 81 to 108% for D-mannitol.