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首页> 外文学位 >Calculation and interpretation of activation energies for the desolvation of cloxacillin, dicloxacillin and nafcillin monohydrate in the solid-state.
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Calculation and interpretation of activation energies for the desolvation of cloxacillin, dicloxacillin and nafcillin monohydrate in the solid-state.

机译：固态氯沙西林，双氯西林和纳夫西林一水合物去溶剂化的活化能的计算和解释。

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摘要

The purpose of this research was to characterize and interpret the desolvation kinetics of a series of penicillin derivative in monohydrates using nonisothermal gravimetric analysis. These results were compared to isothermal gravimetric studies and further interpreted by examining the rehydration of the compounds using a series of moisture adsorption isotherms as well as computer simulated molecular dynamics. Nonisothermal and isothermal studies were conducted using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). To calculate the kinetic parameters and select a model for the reaction mechanism the data were fit to various appropriate mathematical models using linear as well as nonlinear curve fitting. The isothermal results for desolvation were consistent with previous studies in that use of all mechanistic models resulted in similar calculated activation energies and correlation coefficients. There was a small difference in the activation energies calculated by linear regression and by nonlinear regression, however the activation energies and correlation coefficients were still similar for each reaction mechanism within the specific regression model used. Both the linear and nonlinear regression methods for the nonisothermal studies gave similar results. A large variation in the activation energy was found for data fit to the various mechanisms, although no single mechanistic model fit the data the best, the nonisothermal methods did suggest that a diffusion model was more likely than the others. It is likely that the computed desolvation activation energy is the sum of several processes and not a single reaction mechanism. The rehydration studies used to further interpret these activation energies seem to indicate that the mechanism for desolvation upon heating is different than that for desolvation under a vacuum. This finding was further studied with the aid of computer simulated molecular dynamics.
机译：这项研究的目的是使用非等温重量分析法表征和解释一系列青霉素衍生物在一水合物中的去溶剂化动力学。将这些结果与等温重量分析进行了比较，并通过使用一系列水分吸附等温线以及计算机模拟的分子动力学研究了化合物的再水化反应，进一步解释了这些结果。非等温和等温研究使用热重分析（TGA）和差示扫描量热法（DSC）进行。为了计算动力学参数并为反应机理选择模型，使用线性和非线性曲线拟合将数据拟合到各种合适的数学模型。去溶剂化的等温结果与以前的研究一致，因为使用所有机理模型都得出了相似的计算活化能和相关系数。通过线性回归和非线性回归计算的活化能之间存在很小的差异，但是在使用的特定回归模型中，每种反应机理的活化能和相关系数仍然相似。非等温研究的线性和非线性回归方法均得出相似的结果。尽管没有单一的机械模型能够最好地拟合数据，但是发现活化能存在很大的差异，以适应各种机理的数据，但非等温方法的确表明扩散模型比其他模型更可能。计算的去溶剂化活化能很可能是多个过程的总和，而不是单个反应机理。用于进一步解释这些活化能的再水化研究似乎表明，加热时去溶剂化的机理与真空下去溶剂化的机理不同。借助计算机模拟的分子动力学进一步研究了这一发现。

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  • 作者

    Stodghill, Steven Paul.;

  • 作者单位

    The University of Mississippi.;

  • 授予单位 The University of Mississippi.;
  • 学科 Chemistry Pharmaceutical.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 250 p.
  • 总页数 250
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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