Solid State Transformations Mediated by a Kinetically Stable Form
Solid State Transformations Mediated by a Kinetically Stable Form
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DOI：
10.1021/cg2008478
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发表时间：
2012-01-01
影响因子：
3.8
通讯作者：
Seton, Linda
中科院分区：
文献类型：
--
作者：
Khamar, Dikshitkumar;Bradshaw, Ian J.;Seton, Linda
表征了茶碱的无水形式以及与一水合物 M 型的稳定性关系。 II 型在室温下动力学稳定，被认为是 70 年茶碱使用历史中最稳定的形式，据观察，它可以作为其他形式之间转化的中介。 IV 型是室温下热力学稳定的形式，与 H 型具有对映异构关系，并在加热时发生固态转变。研究了 II 型和 I 型之间的对映异构关系，并确定仅在使用特定方法生成的样品中观察到 II 型到 I 型的转变。发现III型是一种高能固体形式，只能通过水合物脱水产生。加热后，III 型放热转变为 H 型。再水合后，III 型吸湿性极强，首先转化为 II 型，然后转化为 M 型。图中展示了无水物-水合物关系的复杂性，并显示了样品历史对批次纯度的影响，这反过来又可能影响固体形态的转变。
The anhydrous forms of theophylline and the stability relationships with the monohydrate, Form M, are characterized. Form II, kinetically stable at room temperature and considered as the most stable form during the 70-year history of theophylline usage, is observed to act as an intermediary for conversions between other forms. Form IV, the thermodynamically stable form at room temperature, is shown to be enantiotropically related to Form H and undergoes a solid state transition on heating. The enantiotropic relationship between Forms II and I was investigated, and it was established that a Form II to I transition is observed only in samples generated using specific methods. Form III was found to be a high energy solid form which can only be generated by dehydration of the hydrate. Upon heating Form III shows an exothermic transition to Form H. Upon rehydration, Form III is extremely hygroscopic and converts initially to Form II and then to Form M. The complexity of anhydrate-hydrate relationships is illustrated, and the influence of sample history on batch purity is shown, which in turn may influence solid form transformations.