Brönsted酸性离子液体催化酯化反应研究

合成了以2-吡咯烷酮和N-甲基咪唑为阳离子([Hnhp]＋和[Hmim]＋), , 和 为阴离子的一系列Brönsted酸性离子液体. 考察了这些离子液体的热稳定性和酸性. 以乙酸和异戊醇酯化合成乙酸异戊酯的反应考察了不同离子液体分别在不分水与分水条件下的催化效果, 结果表明, 不分水时, 当醇/酸/[Hnhp]HSO4物质的量比为1.2∶1∶0.2, 100 ℃下回流反应2 h, 酯收率可达93.6%, 反应结束后[Hnhp]HSO4体系可以顺利分相, [Hnhp]BF4则不能; 分水时, [Hnhp]BF4可与酯自动分相, 当醇/酸/[Hnhp]BF4物质的量比为1.2∶1∶0.01, 120 ℃下回流反应1.5 h时, 酯收率可达96.8%, 比相同条件下[Hnhp]HSO4的略高. 这两种体系中的离子液体均具有良好的重复使用性能. 实验中还探讨了不同离子液体的酸性和催化酯化反应后与酯产物的分相效果对其催化活性的影响, 结果表明, 离子液体的酸性和与酯的不可混溶性对其在不同体系中酯化反应的催化活性有不同程度的影响. 此外, 在上述不分水酯化条件(醇∶酸∶催化剂物质的量比均为1.2∶1∶0.2, 100 ℃油浴)下回流浸渍6 h比较离子液体[Hnhp]HSO4/BF4, [Hmim]HSO4/BF4和硫酸对奥氏体316不锈钢的腐蚀性, 测得离子液体腐蚀率比硫酸低; 除了[Hnhp]BF4, 离子液体[Hnhp]HSO4, [Hmim]HSO4和[Hmim]BF4的腐蚀性呈现随酸性递减而下降的趋势. 所测离子液体中[Hnhp]BF4腐蚀性最高. [Hnhp]BF4和硫酸中试样的腐蚀率分别为20.1和41.8 g/(m2•h).     

低碱法制备羧甲基壳聚糖及表征

低碱法制备羧甲基壳聚糖及表征;壳聚糖;羧甲基壳聚糖;取代度;特性粘度;低碱法     

苯甲醛缩三乙烯四胺Schiff碱Co(Ⅱ)配合物固相合成及氧合性能研究

Three new cobalt complexes were synthesized by solid-state reaction at room temperature. It was found that one mole of complex reacted with two moles of oxygen at room temperature. And the oxygenated complexes [Co·(L₁)₂·2O₂](NO₃)₂·2H₂O (L₁=N,N′-bis(4-hydroxyl-3-methoxy-benzyl)-triethylenetetramine), [Co·(L₂)₂·2O₂](NO₃)₂ ·2H₂O (L₂=N,N′-bis(4-hydroxyl-benzyl)-triethylenetetramine) and [Co·L₃·2O₂](NO₃)₂·2H₂O (L₃=N,N′-bis(2-hydroxyl-benzyl)-triethylenetetramine) were obtained and characterized by elemental analysis, IR spectra, ¹H NMR, TG/DTA, UV-Vis and molar conductance. The coordinated oxygen contents in the oxygenated complex were also determined by weight method. It was found that one O₂ molecule coordinated to the Co ion and formed superoxo type oxygenated complex.     

A Chinese Lantern-like 2D Cu(Ⅱ) Coordination Polymer Constructed by Bis-imidazole and Dicarboxylate Co-ligands: Synthesis,Crystal Structure and Photocatalytic Activity

A new Cu(II) coordination polymer, {[Cu(1,3-BIP)(TFBDC)]·DMF}n(1,1,3-BIP is a 1,3-bis(imidazole)propane, and H2TFBDC is 2,3,5,6-tetrafluoroterephthalic acid) was prepared under solvothermal conditions and characterized by single-crystal and powder X-ray diffraction, IR spectra, thermogravimetric analyses and elemental analyses. The single-crystal X-ray diffraction reveals that metal coordination polymer 1(MCP 1) shows a two-dimensional sheet layer structure, which is further reinforced through strong intermolecular hydrogen bonding to form a 3 D supramolecular framework. Furthermore, the photocatalytic experiment result indicates the degradation ratios of methyl orange(MO) reach 83.4% within 180 minutes when MCP 1 acts as catalyst.     

烯醇-酮互变异构型亚胺衍生物对Co2+的高选择性识别

设计合成了新型烯醇-酮互变异构型亚胺衍生物R, 考察了受体R对18种阳离子的紫外光谱及裸眼识别性能. 结果表明, 该受体对Co²⁺, Fe²⁺和Ni²⁺表现出良好的紫外光谱识别能力, 且可实现对Co²⁺相对明显的裸眼单一识别. Job曲线表明, 受体R与Co²⁺形成了1:1型金属配合物, 且检出限可达4.14×10^-7 mol/L. 制备了受体R裸眼比色识别试纸; 根据理论计算及核磁滴定实验结果阐述了Co²⁺离子识别过程中烯醇-酮互变异构机理.     

基于氦离子化气相色谱法测定微量氧、氮的影响因素

探讨氦离子化气相色谱法测定样品中微量氧、氮含量的影响因素。采用控制变量法,对色谱柱温度、进样流量、进样管道环境及极化电压等因素对微量氧、氮测定结果的影响进行讨论和分析。结果表明,当色谱柱温度为25~45℃时,色谱柱对氧、氮吸附量最小;当进样流量不小于70 mL/min时,微量氧、氮测定结果受外界干扰最小;当极化电压为80~160 V时,氧、氮具有最佳的响应值;初次测定样品中微量氧、氮含量时,需使进样管道表面吸附的氧、氮处于饱和状态,以便获得理想的测定结果。讨论的结果可为氦离子化气相色谱法测定相关样品中微量氧、氮含量时提供技术参考。     

Reactions of 16e CpCo half-sandwich complexes containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolate ligand with ethynylferrocene and dimethyl acetylenedicarboxylate

The reaction of the 16e half-sandwich complex [CpCo(S2C2B10H10)] (1S; Cp: cyclopentadienyl) with ethynylferrocene in CH2Cl2 at ambient temperature leads to [CpCo(S2C2B10H9)-(CH2CFc)] (2S; Fc: ferrocenyl) and 1,2,4-triferrocenylbenzene. In 2S, B substitution occurs at the carborane cage in the position B3/B6 with the formation of a C-B bond. In the presence of the protic solvent MeOH, 2S loses a CpCo fragment to generate [(CH2CFc)(S2C2B10H9)] (3S). On the other hand, 2S can take a free CpCo fragment to form [(CpCo)2(S2C2B9H8)-(CHCFc)] (4S) containing a nido-C2B9 unit. In sharp contrast, [CpCo-(Se2C2B10H10)] (1Se) does not react with the alkyne in CH2Cl2, but in MeOH [(CHCFc)(Se2C2B10H10)] (5Se) is generated without the presence of a CpCo unit. The reaction of 1 with dimethyl acetylenedicarboxylate at ambient temperature leads to insertion compounds [CpCo(E2C2B10H10){(MeO2C)-C=C(CO2Me)}] (6S, E=S; 6 Se, E=Se). Upon heating, 6S rearranges to two geometrical isomers [CpCo(S2C2B10H9){(MeO2C)C=CH(CO2Me)}] (7S) and [CpCo(S2C2B10H9){(MeO2C)-CHC(CO2Me)}] (8S). In both, B-H functionalization takes place at the carborane cage in the position B3/B6, but 7S is a 16e complex with an olefinic unit in a Z configuration, and 8S is an 18e complex containing an alkyl B-CH group. Further treatment of 7 S with dimethyl acetylenedicarboxylate at ambient temperature affords two B-disubstituted complexes at the carborane cage in the positions of the B3 and B6 sites, that is, [CpCo(S2C2-B10H8){(MeO2C)C=CH(CO2Me)}2] (9S) and [CpCo(S2C2B10H8){(MeO2C)-CHC(CO2Me)}{(MeO2C)C=CH-(CO2Me)}] (10S). Compound 9S is a 16e complex with two olefinic units in E/E configurations, whereas 10S is an 18e species containing both an olefinic substituent and an alkyl B--CH unit. The reaction of 7S with methyl acetylenemonocarboxylate at ambient temperature leads to the sole 16e compound [CpCo(S2C2B10H8){CH=CH(CO2Me)}-{(MeO2C)C=CH(CO2Me)}] (11S). In contrast, 6Se does not rearrange. All new complexes 2S-4S, 5Se, 6Se, and 7S-11S were characterized by NMR spectroscopy (1H, 11B, 13C) and X-ray structural analyses were performed for 2S-4S, 5Se, 6Se, and 7S-9S.     

Hydrothermal Synthesis and Thermal Stability of Natural Mineral Lindgrenite

IntroductionSynthesis of natural minerals is helpful for tracingthe geological origin of mineral formation and forverifying the quality of minerals. The investigations onthe conditions for mineral formation, such as pressure,temperature, and starting mate…     

Characterization and separation of Al_(13) species using gel-filtration chromatography

Polyaluminum chloride (PAC) coagulant has been developed and widely used in water and wastewater treatment industry since the 1980s[1]. PAC is normally made by partial hydrolysis of acid aluminum chloride solution using slow alkaline titration method. However, this method would result in many different Al species. Among these Al species, it seems that tridecamer (Al13O4(OH) 724 , often denoted by Al13) is the most effective and stable polymeric Al species for water and wastewater treatme…     

我国油料产品品质的近红外光谱快速检测技术研究进展

近红外光谱技术是一种快速无损检测技术,具有操作简单、检测成本低、无需化学试剂、绿色环保,以及可实现多品质参数同步检测等优点。该文综述了我国油料和食用植物油品质的近红外光谱速测技术研究进展,包括油料含油量、粗蛋白含量、脂肪酸含量等品质指标,食用油的理化指标,以及脂肪酸和食用油的真实性鉴别,并对油料产品品质的近红外光谱速测技术的发展前景进行了展望。