共查询到17条相似文献,搜索用时 125 毫秒
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应用等温流动微量热法测定了298.15 K时互为旋光异构体的D-甘露醇与D-山梨醇在不同浓度的氯化钠水溶液中的稀释焓, 利用 McMillan-Mayer 理论计算了D-甘露醇与D-山梨醇在不同浓度的氯化钠水溶液中的焓对相互作用系数. 结果表明, D-甘露醇和D-山梨醇在氯化钠水溶液中的焓对相互作用系数h2均为正值, h2的值随着氯化钠浓度的增加皆逐渐增大, 但D-山梨醇的焓对相互作用系数h2增大的速率[dh2 /dm(NaCl)]比 D-甘露醇的要大. 根据两多元醇分子构象结构的差异, 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. 相似文献
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应用流动式等温精密微量热技术测定了298.15, 303.15, 308.15, 313.15和318.15 K 5个不同温度下L-胱氨酸在一种强酸性和两种强碱性溶剂中的稀释焓. 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级焓相互作用系数(h2)和二阶熵相互作用系数(s2), 根据溶质-溶质, 溶质-溶剂等弱相互作用对二阶焓、熵相互作用系数进行了讨论. 结果表明: 对在水相中胱氨酸的二阶相互作用而言, 二价阳离子比二价阴离子具有较强的介质效应; 不同温度下的二阶焓相互作用系数与温度成线性关系, 因而二阶熵相互作用系数在实验温度范围内为一常量. 相似文献
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丝氨酸在蔗糖水溶液中的稀释焓 总被引:2,自引:0,他引:2
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. 相似文献
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由于糖具有特殊的生物和生理性质 ,在工业生产中已有广泛应用 ,故其溶液热力学性质已成为人们感兴趣的研究课题之一 .糖在水溶液中的热力学性质已见文献报道 [1] ,但在非水体系中的有关数据则较少报道 .研究表明 ,溶剂介质的变化对溶质的溶剂化状态和溶质间相互作用的影响较大 ,选用酰胺为溶剂可以获得模拟蛋白质环境条件下的溶质 -溶剂、溶质 -溶质间相互作用的信息 [2~ 4] .本文利用微量量热法测得了葡萄糖在杂环化合物与甲酰胺的混合溶剂中的溶解焓 .如果把杂环化合物作为 x,葡萄糖作为 y,按照 Mc Millan- Mayer[5 ] 理论 ,1 mol葡萄… 相似文献
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盐湖盐类水溶液298.15K时稀释热和表观摩尔焓的研究 总被引:4,自引:1,他引:4
有关溶稀释热方面的研究报导很多,例如等溶液的稀释热均已有文献值.但全是采用分批式量热法研究部分间断浓度范围内的稀释热,数据设有连续性,很不全面.在稀释热理论估算方面,Pitier的半经验溶液理论能比较满意的解决一般浓溶液的稀释热估算问题,但文献只给出了某些多数,没有计算出具体的稀释热数据[6-9],也没有将实验测定值与理论估算值相比较.基于Debye-Hckel理论推导出的烙极限公式[10-12]在溶液表观摩尔烂的研究中已得到广泛应用.但迄今没有一篇论文比较全面地将实验测定与Pitier理论和Debye-Hhdel极限公式相结合来研究溶… 相似文献
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Qiang Zhao Qing-Xiang Lu Min Liu De-Zhi Sun Lin-Wei Li 《Journal of solution chemistry》2009,38(2):231-240
The concentration effect on the dilution enthalpies (Δdil
H
m) of colchicine (COL) in aqueous NaCl solutions has been investigated by isothermal titration microcalorimetry at 298.15 K.
The corresponding homogeneous enthalpic interaction coefficients have been calculated according to the excess enthalpy concept.
The results show that the dilution enthalpies of COL in aqueous NaCl solutions at different mass fractions are positive. The
overall trend is that enthalpies of dilution become more positive with the increase of the salt mass fraction. The values
of enthalpic pair-wise interaction coefficients, h
2, have been obtained by fitting the data of the enthalpies of dilution with a viral expansion. The results can be interpreted
from the view of solute-solute and solute-solvent interactions involved in the solvent effects. 相似文献
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The enthalpies of solution and of dilution of 1-butanol and 1-pentanol were measured in micellar solutions of dodecyltrimethylammonium bromide by systematically changing the concentration of alcohols and surfactant. The enthalpies of solution at infinite dilution of alcohols at each surfactant concentration were evaluated from a linear plot. This quantity increases with surfactant concentration (up to 0.8m) with a curvature which depends on the alcohol alkyl chain length. The difficulties arising for a quantitative treatment of both the enthalpies of dilution and of solution at finite alcohol concentrations are discussed. The dependence on the surfactant concentration of the standard enthalpies of solution and the enthalpies of dilution for m0 are rationalized. From the resulting equations the distribution constant, standard enthalpy of transfer, standard enthalpy of solution, and the alcohol-alcohol interaction parameter in the micellar phase are evaluated. The enthalpies of transfer obtained using this technique agree well with those previously reported from enthalpies of mixing. The distribution constants also agree with those reported in the literature from several approaches: mixing enthalpies, partial molar volumes, and the dependence of the cmc on added alcohol. 相似文献
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键连接性指数的建构及其在有机体系中的应用研究 总被引:3,自引:0,他引:3
以化学键为基础建构了键连接性指数及分子键连接性指数,该指数同时考虑顶 点原子的化学特征及键的性质.对于任意化学键,键连接性指数Si=1+△I/R·[( Z1-h1)m2/n1+(Z2-h2)m1/n2],分子键连接性指数S为∑i=1^m√Si或∑i=1^m1/√ Si,其中,Z1,Z2为化学键键连原子的价电子数;n1,n2成键原子的价层最高主量 子数;m1,m2为成键原子的氧化数;h1,h2为与成键原子相连的氢原子个数;△I 为成键原子的电负性差(△I≥0);R为化学键的相对键长.与以顶点为基础的价连 接性指数不同,该指数不仅能方便而有效地应用于饱和碳氢体系亦能有效地应用于 含多重键的不饱和体系及含杂原子的有机体系.研究了饱和碳氢体系标准生成焓, 不饱和碳氢体系和酮、醚、酯体系在水中的溶解度和辛醇/水分配系数,卤代甲烷 体系的标准生成焓,卤代苯体系辛醇/水分配系数,均取得比较满意的结果。 相似文献
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The effect of pH on the dilution enthalpies of D-p-hydroxyphenylglycine in phosphate buffer solutions has been investigated by isothermal titration microcalorimetry at 298.15 K. The corresponding homogeneous enthalpic interaction coefficients have been calculated according to the excess enthalpy concept. The results show that the enthalpies of dilution of D-p-hydroxyphenylglycine in phosphate buffer solutions at different pH are all positive. The overall trend is that enthalpies of dilution become more positive with an increase of pH, but there is a minimum of the enthalpy of dilution at pH = 7.0. The enthalpic pair interaction coefficients, h
2, all have negative values. The results are interpreted from the point of view of solute-solute and solute-solvent interactions involved in the solvent effects. 相似文献
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《The Journal of chemical thermodynamics》2007,39(8):1201-1205
Solution and solvation enthalpies at infinite dilution of 1-bromoadamantane, 1-adamantanol, and 2-adamantanone are reported at 298.15 K in a set of 14 aprotic solvents. The specific interaction enthalpies of the solid solutes are calculated using a methodology recently published by other authors. 1-Adamantanol’s specific interaction enthalpies show a good correlation with the Kamlet–Taft β scale. 相似文献