2-(4′-硝基苯乙烯基)苯并恶唑及其衍生物的合成与同质多晶性

Synthesis and Polymorphism of 2-(4'-Nitrostyryl)-Benzoxazole and Its Derivatives

合成了2-(4′-硝基苯乙烯基)苯并恶唑及其5位甲基、硝基、乙酰氨基和苯基取代的衍生物,利用差热分析和多晶X射线衍射测定了它们的受热行为并鉴定了它们的同质多晶性。结果表明:这些化合物都是热不稳定的,一经受热便会发生晶型的转变,主要原因在于α晶型熔点较低并且晶格能较小,受热熔融后的熔体相对β晶型是过冷液体。

2-(4'-nitrostyryl)-benzoxazole and its 5-position methyl, nitro, acetamino, and phenyl substituted derivatives were synthesized. Their thermal behaviors and polymorphism were determined by DSC and X-Ray diffraction, respectively. The results show that they have α, β two modifications, the α-modification is thermo-unstable and can transform into β-modification on heating. △H_m, AS_m and melting point of the α-modification are lower than those of the β-modification, The fused liquid of the α-modification is a supercooled liquid as compared with the β-modification.