Crystal structures and theoretical investigation of anti-/syn-2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols

2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory (DFT) method at B3LYP/6-31G (d) level. The structure of syn-2,4-di-p-tolylpentane-2,4-diol (2b) was characterized by X-ray diffraction and compared with the crystal structures of anti- and syn-2,4-diphenylpentane-2,4-diols (1a and 1b). X-ray diffraction indicates that inter and intra-molecular hydrogen bonds are formed in the crystal structures. There is π-π staking interaction in 1b and 2b. Good linear correlations and similar results are found between the experimental ¹H and ¹³C NMR chemical shifts (δ _exp) and GIAO (Gauge Independent Atomic Orbital) method calculated magnetic isotropic shielding tensors (δ _calc). HOMO and LUMO molecular orbitals were calculated at the same levels with the different results. UV-vis absorption spectra of the compounds were recorded in EtOH, MeCN, n-BuOH and cyclohexane with different dielectric constants. It is found that the solvent effect is obvious when ɛ is 24.85(EtOH), 35.69(MeCN) and it is weak when ɛ is decreased to 17.33(n-BuOH), 1.18 (cyclohexane).     

温度和pH双重敏感型聚氨酯水凝胶的制备及性能

以聚乙二醇(PEG)、4,4’-二苯基甲烷二异氰酸酯(MDI)、三羟甲基丙烷(TMP)为主要原料,分别采用1,4-丁二醇(BDO)、N-甲基二乙醇胺(MDEA)、2,2-二羟甲基丙酸(DMPA)为扩链剂,制备了3种聚氨酯水凝胶Hydrogel(a)、Hydrogel(b)、Hydrogel(c)。通过红外光谱、差示扫描量热分析、X射线衍射和溶胀实验对水凝胶的结构和性能进行了分析。研究结果表明,温度敏感链段(PEG)和pH敏感基团(-N(CH_3)-、-COOH)均成功地引入到了水凝胶分子链中;3种水凝胶的相转变温度分别为55℃、60℃和64℃,且合成后水凝胶中PEG的结晶结构仍然存在;当水溶液温度从45℃上升到60℃时,3种水凝胶的平衡溶胀度均显著减小,显示出温度敏感性;当pH从4.0上升到7.0时,Hydrogel(c)的平衡溶胀度从11.5增大到15.5,当pH从8.5上升到11.5时,Hydrogel(b)的平衡溶胀度从12.9减小到10.0,均显示出pH敏感性;在不同温度(25℃和65℃)和pH(2.5和11.5)的水溶液中反复溶胀,水凝胶Hydrogel(b)和Hydrogel(c)均表现出良好的可逆性和稳定性。     

酰胺咪唑啉季铵盐合成及其缓蚀性能

以高纯环烷酸为原料合成了系列酰胺咪唑啉季铵盐水溶性缓蚀剂,探讨了其咪唑啉环N₍₁₎原子上取代基与缓蚀性能之间的关系。采用取代基电子效应法和碳钢挂片失重法,从理论与实验两方面探讨了酰胺咪唑啉季铵盐对碳钢的缓蚀性能。利用数理统计方法得出,其缓蚀效率(η)与基团极化效应参数(PEI_x)和-C=C-键效应指示变量D之间符合定量线性关系η = a + b PEI_x + c D(a,b,c为常数),相关系数R≥0.996。该研究成果,能为离子型缓蚀剂分子设计提供一种简便易行的新方法,为找到具有更佳缓蚀性能的新型咪唑啉缓蚀剂提供参考。     

邻氨基苯甲醇烷基化合成2-(2-羟甲基苯基氨基)乙酰芳胺

研究了2-溴乙酰芳胺对邻氨基苯甲醇的烷基化反应,反应主要发生在N原子上,并由此合成了一系列新型芳胺基取代乙酰芳胺类化合物(4a~4e)。对反应溶剂、碱的种类及用量、反应温度、时间、反应物的量之比等条件对反应的影响进行了研究,获得优化反应条件。在优化条件下化合物4a~4e的收率为68.9%~72.8%。对反应影响比较大的因素主要是溶剂,采用v(N,N-二甲基甲酰胺)∶v(四氢呋喃)=1∶2的混合溶剂可使反应收率从36.1%(THF中)提高到70.3%。用IR、1H NMR和13C NMR对化合物4a~4e的结构进行了分析与表征。