Two crystalline polymorphic forms of α-(N-benzoxazolin-2-one)acetic acid

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• 作者：J. M. Ashurov ; L. Yu. Izotova ; B. T. Ibragimov…
• 关键词：α ; (N ; benzoxazolin ; 2 ; one)acetic acid ; polymorphism ; crystal structure
• 刊名：Russian Journal of Physical Chemistry A
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：91
• 期：1
• 页码：106-110
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Physical Chemistry;
• 出版者：Pleiades Publishing
• ISSN：1531-863X
• 卷排序：91

文摘

Two crystalline polymorphic forms of α-(N-benzoxazolin-2-one)acetic acid (BAA) are prepared by changing the temperature of its crystallization from solution in ethanol. Crystallographic data of the α-form are determined: a = 12.7769(17) Å, b = 8.2574(9) Å, c = 16.7390(19) Å, β = 105.087(13)°, space group C2/c, V = 1705.2(4) Å3, and Z = 8, while those of β form are a = 5.2854(4) Å, b = 5.9880(4) Å, c = 13.4509(5) Å, β = 94.666(4)°, space group P2₁, V = 424.30(4) Å3, and Z = 2. It is found that BAA molecules of the α form combine into infinite one-dimensional chains arranged along axis b by means of O‒H···O and C‒H···O hydrogen bonds, and these chains are crosslinked via C‒H···O hydrogen bonds to form a threedimensional structure. The β form has another system of hydrogen bonds, one of which is bifurcated (O4···O2, O4···O3), and the π–π-interactions between the benzoxazolinone fragments of BAA molecules combined into a chain also arranged along axis b are observed. Calorimetric analysis shows that the polymorphic transition from the α form to the β form occurs at 129°C.