Mechanically induced phase change in barbituric acid
Mechanically induced phase change in barbituric acid
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DOI：
10.1021/cg701214k
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发表时间：
2008-05-01
影响因子：
3.8
通讯作者：
Venturello, Paolo
中科院分区：
文献类型：
--
作者：
Chierotti, Michele R.;Gobetto, Roberto;Venturello, Paolo
通过研磨巴比妥酸的三氧代形式（多晶型II，99%）的商业样品24小时，分离出一种新化合物。新相已被确定为三羟基异构体。用X射线粉末衍射、固体核磁共振（H-1 MAS、C-13和N-15 CPMAS、2D PASS和FSLG-HETCOR）、红外光谱和拉曼光谱对新异构体进行了表征。该转化是由一个亚甲基和两个N-H氢原子的完全互变异构位移引起的。H-1 MAS光谱允许在起始化合物和新异构体中的氢键相互作用的强度的基础上进行表征。在溶液中，三羟基异构体立即转化为三氧代形式，如在质子、非质子和两性溶剂（D2 O、MeOH-d（4）、DMSO-d（6）、丙酮-d（6））中的H-1 NMR实验所证明的。
By grinding a commercial sample of barbituric acid in its trioxo form (polymorph II, 99%) for 24 h, a new compound has been isolated. The new phase has been identified as the trihydroxyl isomer. The characterization of the new isomer has been carried out by means of X-ray powder diffraction, solid-state NMR (H-1 MAS, C-13 and N-15 CPMAS, 2D PASS, and FSLG-HETCOR), IR and Raman spectroscopies. The conversion results from the complete tautomeric shift of a methylene and of two N-H hydrogen atoms. H-1 MAS spectra allow the characterization of the hydrogen bond interactions on the basis of their strength in the starting compound and in the new isomer. In solution, the trihydroxyl isomer immediately converts to the trioxo form as demonstrated by H-1 NMR experiments in protic, aprotic, and amphiprotic solvents (D2O, MeOH-d(4), DMSO-d(6), acetone-d(6)).