双氟取代苯和联苯类液晶化合物的量子化学研究

运用AM1和PM3两种SCF-MO方法,通过能量梯度全优化计算,给出了对一系列环上双氟取代苯、联苯液晶化合物的稳定几何构型、电子结构和分子基本性质(生成热、偶极矩、前沿分子轨道能级等)。联系有机结构理论进行了分析和讨论。初步阐明了其分子结构与介电各向异性之间的关系,为设计和开发新型液晶分子研究提供了有较大价值的线索。     

Zn/AlCl3促进下二硫醚与α,β-不饱和化合物的共轭加成

二芳基二硫醚与锌粉在DMF 中110 ℃反应, 生成二硫醚与锌的复合物; 后者在无水AlCl₃存在下与丙烯酸酯、丙烯腈反应分别生成β-芳硫基丙酸酯和相应的腈, 产率48%～91%.     

N-羟基丁二酰亚胺的合成

N 羟基丁二酰亚胺是一种重要的有机中间体 ,可用于多肽合成中的外消旋抑制剂[1 ] 和一些抗菌素的合成 ,也可用于制备活性酯[1～ 3] 。近年来在生物活性分子的合成[4] 及乙烯型聚合物的分子量控制[5]上也获得了广泛的应用。N 羟基丁二酰亚胺的合成早已有报道[6] ,但收率较低。Hoppe Seyler′s[7] 以水和二氧六环作为丁二酸酐与羟胺反应的混合溶剂 ,加热环合脱水 ,然后用乙酸乙酯反复提取 ,虽可得到75 %收率 ,但产物中往往混有 5 %～ 1 0 %的丁二酸难以除去 ,若要获得商品级产物 ,后处理过程复杂 ,且要损失 1 5 %～ 2 0 %的产物[8] 。Cherut…     

Synthesis and Thermal Decomposition Mechanism of Rare Earth （RE=La, Y, Gd） Salicylates

The rare earth (RE=La, Y, Gd) salicylates were synthesized by the rheological phase reaction method. The complexes were characterized by elemental analysis, infrared spectra (IR), X-ray powder diffraction (XRD) and thermal gravity analysis (TG). They can be represented by general formula RE(HSal)3 (RE=La, Y, Gd; HSal=C6Ha(OH)COO). The crystals of them are monoclinic and have layered structure. The mechanism of thermal decomposition of rare earth salicylates was studied by using TG, DTA, IR and gas chromatography-mass spectrometry (GC-MS). The thermal decomposition of the rare earth salicylates in nitrogen gas proceeded in three stages: firstly, they were decomposed to form RE2(Sal)3 (Sal=C6H4OCOO) and salicylic acid; then, RE2(Sal)3 were decomposed further to form RE2O(CO3)2 and some organic compounds; finally, RE2O(CO3)2 were decomposed to form rare earth metal oxides (RE2O3) and carbon dioxide. The organic compounds obtained from the second step of the reaction are mainly dibenzofuran, xanthenone, 6H-benzo[c]chromen-6-one, 6-phenyl-6H-benzo[c]chromene, and 1,3-diphenyl-1, 3-dihydro-2-benzofuran.