Solubility and thermodynamic properties of sodium theophylline salt in aqueous sodium hydroxide solution at different temperatures

Journal of Chemical Research-s Pub Date : 2023-03-01 DOI:10.1177/17475198231166563

Zhe Dong, L. Kong, Zhen Liu, Anming Yang

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Abstract

The solubility data of sodium theophylline salt in the water and aqueous sodium hydroxide systems with molarities of 0.00, 0.01, 0.10, 0.20, 0.49, and 0.96 mol kg−1 at temperatures ranging from 283.15 to 368.15 K are determined via the equilibrium method. The experimental results show that the solubility of sodium theophylline increases on increasing the temperature at the same concentration of NaOH solution and decreases with an increase in the NaOH concentration at the same temperature. These results correlate well with the polynomial empirical equation, the modified Apelblat equation, and the λh equation. At the same time, it is found that the modified Apelblat equation gives better correlation results than the polynomial empirical and the λh equations. The results show that the three models correlate well with the solubility data of sodium theophylline. The modified Van’t Hoff equation is used to estimate the thermodynamic properties including the dissolution enthalpy, the dissolution entropy, and the Gibbs free energy change of sodium theophylline when dissolved in aqueous NaOH solution at different concentrations. The solubility data and correlation results obtained from the experiments can provide basic data for the cooling crystallization, separation, and purification of sodium theophylline and are expected to be of great significance for the research and development of sodium theophylline and for caffeine production.

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不同温度下茶碱钠在氢氧化钠水溶液中的溶解度和热力学性质

在283.15 ~ 368.15 K的温度范围内，用平衡法测定了茶碱钠在水和氢氧化钠水溶液中的溶解度数据，其摩尔浓度分别为0.00、0.01、0.10、0.20、0.49和0.96 mol kg−1。实验结果表明，在相同NaOH浓度下，茶碱钠的溶解度随NaOH浓度的升高而升高，随NaOH浓度的升高而降低。这些结果与多项式经验方程、修正Apelblat方程和λh方程具有良好的相关性。与此同时，修正的Apelblat方程比多项式经验方程和λh方程具有更好的相关结果。结果表明，三种模型与茶碱钠的溶解度数据吻合良好。利用修正的Van 't Hoff方程估计了茶碱钠在不同浓度NaOH水溶液中的溶解焓、溶解熵和吉布斯自由能变化等热力学性质。实验得到的溶解度数据和相关结果可为茶碱钠的冷却结晶、分离纯化提供基础数据，对茶碱钠的研究开发和咖啡因的生产具有重要意义。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Chemical Research-s 化学科学, 有机化学, 有机合成

自引率

0.00%

发文量

审稿时长

1 months

期刊介绍： The Journal of Chemical Research is a peer reviewed journal that publishes full-length review and research papers in all branches of experimental chemistry. The journal fills a niche by also publishing short papers, a format which favours particular types of work, e.g. the scope of new reagents or methodology, and the elucidation of the structure of novel compounds. Though welcome, short papers should not result in fragmentation of publication, they should describe a completed piece of work. The Journal is not intended as a vehicle for preliminary publications. The work must meet all the normal criteria for acceptance as regards scientific standards. Papers that contain extensive biological results or material relating to other areas of science may be diverted to more appropriate specialist journals. Areas of coverage include: Organic Chemistry; Inorganic Chemistry; Materials Chemistry; Crystallography; Computational Chemistry.