单斜晶系
结晶学
单晶
正交晶系
相(物质)
材料科学
焓
Crystal(编程语言)
晶体结构
微晶
化学
热力学
有机化学
物理
计算机科学
程序设计语言
作者
Menahem Kaftory,Mark Botoshansky,Moshe Kapon,Vitaly Shteiman
出处
期刊:Acta crystallographica
[International Union of Crystallography]
日期:2001-11-29
卷期号:57 (6): 791-799
被引量:34
标识
DOI:10.1107/s0108768101014987
摘要
4,6-Dimethoxy-3-methyldihydrotriazine-2-one (1) undergoes a single-crystal to single-crystal reversible phase transformation at 319 K. The low-temperature phase crystallizes in monoclinic space group P2(1)/n with two crystallographically independent molecules in the asymmetric unit. The high-temperature phase is obtained by heating a single crystal of the low-temperature phase. This phase is orthorhombic, space group Pnma, with the molecules occupying a crystallographic mirror plane. The enthalpy of the transformation is 1.34 kJ mol(-1). The small energy difference between the two phases and the minimal atomic movement facilitate the single-crystal to single-crystal reversible phase transformation with no destruction of the crystal lattice. On further heating, the high-temperature phase undergoes methyl rearrangement in the solid state. 2,4,6-Trimethoxy-1,3,5-triazine (3), on the other hand, undergoes an irreversible phase transformation from single-crystal to polycrystalline material at 340 K with an enthalpy of 3.9 kJ mol(-1); upon further heating it melts and methyl rearrangement takes place.
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