Nucleophilic activity of peroxyhydrocarbonate and peroxocarbonate ions relative to 4-nitrophenyl diethyl phosphonate

Peroxocarbonate ions HCO ₄ ^? and CO ₄ ^2? , which are formed in the H₂O₂/NH₄HCO₃/HO^? system, react with 4-nitrophenyl diethyl phosphonate (I) through a nucleophilic mechanism with rate constants \(k_{HCO_4^ - } = 0.008\) and \(k_{CO_4^{2 - } } = 0.13 L/mol \cdot s\). Comparison of these constants with the corresponding constants of other inorganic anions in their reaction with I in the framework of the Brönsted equation indicates that HCO ₄ ^? and CO ₄ ^2? are typical α-nucleophiles.     

Mg-Al-O-t-Bu hydrotalcite as an efficient catalyst for the transesterification of dimethyl carbonate with ethanol

Mg-Al-O-t-Bu hydrotalcite was synthesized and characterized by XRD, FT-IR and TGA-DTA. It was proved to be an active heterogeneous catalyst for the transesterification of dimethyl carbonate (DMC) with ethanol. When the reaction was carried out over Mg-Al-O-t-Bu hydrotalcite at 80°C, 7 h, molar ratio of ethanol to DMC 5:1, 1.0 wt.% of catalyst, the conversion of DMC was 86.4%, the selectivity to diethyl carbonate (DEC) was 61.2%. This heterogeneous catalyst could be used 5 times without loss of its activity.     

Composition of heteroassociates formed in a binary liquid system HF-Et<Subscript>2</Subscript>O

IR spectra and densities of solutions in a binary liquid system (BLS) HF-Et₂O were measured for the first time for the molar ratios of the components ranging from 1: 12 to 14: 1 and 31: 1, respectively. An analysis of the concentration dependences of the normalized (to the total number of moles of the BLS components in 1 L) absorbance and excess density of the studied solutions revealed that they contained heteroassociates with stoichiometric ratios of the molecules of 1: 2, 2: 1, 4: 1, and 11–12: 1. The concentration range in which each associate is formed in the binary mixture HF-Et₂O was estimated for all the associates. The results obtained were compared with the data on the HF: Solv ratios (Solv is solvent) in molecular complexes that prevail in the seven BLS HF-organic solvent studied earlier. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1833–1839, September, 2008.     

Three-component condensation of diethyl isophthaloyldiacetate, aromatic aldehyde, and urea as a new method for the synthesis of 1,3-bis(2-oxo-1,2,3,4-tetrahydropyrimidin-6-yl)benzenes

Condensation of diethyl isophthaloyldiacetate, aromatic aldehyde, and urea in the presence of Me₃SiCl proceeds efficiently and faster than in the absence of the latter to form 1,3-bis(2-oxo-1,2,3,4-tetrahydropyrimidin-6-yl)benzene derivatives capable to give inclusion complexes with DMF. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1233–1239, June, 2008.     

三氟化硼乙醚催化合成1-(氨基甲酰基甲基)-2-烃基-3,1-苯并噁嗪类化合物

研究了三氟化硼乙醚(BF₃·OEt₂)催化2-(N-取代氨基甲酰基甲基氨基)苯甲醇与醛的反应,发展了合成取代3,1-苯并噁嗪类化合物的方法,通过该方法合成了一系列新型结构的1-(氨基甲酰基甲基)-2-烃基-3,1-苯并噁嗪类化合物。 对于这类反应BF₃·OEt₂比三甲基氯硅烷(TMSCl)和四氯化锡(SnCl₄)的普适性更广,它能有效催化这类反应,而后二者却不能。 探讨了TMSCl和SnCl₄不能催化2-(N-取代氨基甲酰甲基氨基)苯甲醇与醛反应的原因。     

乙醚团簇在纳秒激光场中的多价电离及其电子能量分布的研究

用5ns,1064nm的脉冲Nd:YAG激光,研究了乙醚团簇与纳秒激光的相互作用.在10¹¹ W/cm²量级光强下,观察到价电子完全剥离的O⁶⁺,C⁴⁺,且这些高价离子的强度比值基本不随激光能量而变化.用阻滞电压方法测量了电离过程中溢出电子能量分布,在最大激光能量4.0×10¹¹ W/cm²,溢出电子的平均能量为56eV,最大能量为102eV.实验结果支持了高价离子产生的“多 关键词： 高价离子 电子能量 纳秒激光 乙醚团簇     

一氧化碳偶联制草酸二乙酯用Pd-Fe/α-Al2O3催化剂的表面结构

 应用XPS,XRD,TEM和TPR等表征技术研究了CO常压气相偶联合成草酸酯反应体系中Pd-Fe/α-Al2O3催化剂的表面结构. 结果表明,催化剂表面的活性组分钯以高度分散的Pd0形式存在,分散的钯微晶平均粒径约为8 nm; 助剂铁以Fe2+形式存在,其分散度极高. 根据表征实验结果,讨论了活性组分、助剂和载体三者之间的相互作用. 助剂可以优先高度分散在载体表面,而活性组分会自动落位在助剂层上达到均匀分散,即催化剂表面形成了类似于金属-金属氧化物-载体相间的结构.     

Phase equilibria of (water + levulinic acid + dibasic esters) ternary systems

Liquid–liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + levulinic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at 298.15 K and 101.3 ± 0.7 kPa. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. The LLE data were correlated fairly well with UNIQUAC and NRTL models, indicating the reliability of the UNIQUAC and NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (α = 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.     

乙酸稀土盐催化缩聚合成聚(对苯二甲酸乙二酯-co-己二酸乙二酯)

合成了一系列乙酸稀土盐(乙酸钇,乙酸镧,乙酸钕,乙酸镝),作为单组分催化剂,采用熔融缩聚法催化对苯二甲酸二甲酯、乙二醇和1,6-己二酸的共缩聚反应,制备了芳香族脂肪族共聚酯——聚(对苯二甲酸乙二酯-co-己二酸乙二酯)(PETA).通过1H-NMR,SEC,DSC及力学性能测试表征了聚合物的序列结构,分子量及分布,热性能及机械性能.结果表明,乙酸稀土盐单组分可催化共缩聚反应,效果优良,能够合成高分子量和较窄分子量分布的共聚酯,共聚酯具有较高的拉伸强度和断裂伸长率.     

Electrosynthesis of highly conducting poly(1,5-dihydroxynaphthalene) in BF3·Et2O

Direct anodic oxidation of 1,5-dihydroxynaphthalene (DHN), an important derivative of naphthalene, led to the formation of high-quality semiconducting poly(1,5-dihydroxynaphthalene) (PDHN) on stainless steel sheets in boron trifluoride diethyl etherate (BFEE). The onset oxidation potential of DHN in this medium was measured to be only 0.78 V vs. SCE, which was lower than that determined in traditional acetonitrile containing 0.1 mol/L tetrabutylammonium tetrafluoroborate (0.98 V vs. SCE). As-formed PDHN films showed good redox activity and stability, together with interesting electrochromic property from brown (doped) to yellow-green (dedoped). Structural characterization, including FTIR, ¹H NMR, and quantum chemistry calculations, indicated that the polymerization of DHN probably occurred at C₄ and C₈ positions. Moreover, thermal analysis revealed that PDHN displayed better thermal stability than that synthesized by chemical method. The fluorescence spectral studies, together with the electrical tests, showed that PDHN was a good blue light-emitter (fluorescence quantum yield higher than 0.1) with an electrical conductivity of as high as 0.46 S/cm.