Studies of the Factors Controlling Regioselective Nucleophilic Addition to Dienylium-Iron Complexes

Tricarbonyl(4-alkoxyl-1-alkylcyclohexadienylium)iron complexes (I) react with metal-cation enolate nucleophiles to give in most cases a mixture of products (II) and (III), resulting from attack at the C-1 and C-5 termini of the dienylium ring. Factors that control the regioselectivity of nucleophilic addition, including the steric and electronic effects of the 4-alkoxyl and 1-alkyl substituents, the degree of association between the enolate nucleophiles and their counterions, and the polarity of the solvents, were investigated.     

NaCl(或KCl)-CH3OH-H2O体系的摩尔电导

CHaOH－HzO体系具有非常特殊的性质，同时在工业生产及临床治疗方面有着十分广泛的应用，文献中有大量地从不同角度就这类体系进行研究的报道．然而，就N3CI及KCI－CH30H－H20体系的电导研究而言，文献中仅有关干KCI－CH30H－H20（间隔20％CH30H）的部分研究工作．作为全面、系     

SYNTHESIS OF ORGANOGERMANE OLIGOMERS VIA LIGAND SUBSTITUTION POLYMERIZATION FROM 1, 4-DIOXANE COMPLEX OF GERMANIUM DICHLORIDE

Some organogermanium oligomers with different side groups were synthesized via li-gand substitution polymerization from 1, 4-dioxane complex of germanium dichloride withdifferent organolithitum compounds. The oligomers were isolated through either precipi-tation from methanol or extraction using toluene with a yield of no less than 50%. Theweiglit average molecular weight (M_w) of the oligomers is ranging from 1.4×10~3 to 5.9×10~3depending on the type and alkyl length of the organolithium compounds used.     

等压试验中平衡过程的理论研究

本文分析了等压实验中温度因素的影响和各种单独过程的平衡方程,理论研究得到了实验设备中的温度差和测定的平衡浓度误差的关系以及平衡方程,平衡方程也表明了各单独过程的平衡速度大小顺序为气相中的水蒸气扩散过程＜气相中的水蒸气循环流动过程＜试样溶液中热传导过程＜热传导体中的热传导过程和试样溶液中由搅拌产生的热传递过程＜溶质在溶液中的扩散过程＜气液相之间的平衡过程和由压强差产生的气相的水蒸气对流过程.同时,研究表明总的平衡方程可以近似由dln|△me,b/m0|/dt=-k·mb2/(ma·wa)描述.此外研究也表明排除等压实验设备中的空气成分可以有效的加快总的平衡速度.并且实验容器与热传导体之间的接触也非常重要.     

Adsorption recovery of thorium(IV) by Myrica rubra tannin and larch tannin immobilized onto collagen fibres

Novel adsorbents which can concentrate Th(IV) in aqueous solution were prepared by immobilizingMyrica rubra tannin and larch tannin onto collagen fibre matrices. The adsorption capacities of the immobilized tannins to Th(IV) are related to temperature and pH value of the adsorption process. For example, when the initial concentration of Th(IV) was 116.0 mg·l^-1 and the immobilized tannin was 100 mg, the adsorption capacities of immobilized Myrica rubra tannin and larch tannin were 55.98 mg Th(IV)·g^-1 and 13.19 mg Th(IV)·g^-1, respectively at 303 K, and 73.67 mg Th(IV)·g^-1 and 18.19 mg Th(IV)·g^-1 at 323 K. It was also found that the higher adsorption capacity was obtained at higher pH value. The adsorption equilibrium data of the immobilized tannins for Th(IV) can be well fitted by the Langmuir model and the mechanism of the adsorption was found to be a chemical adsorption. In general, the adsorption capacity of immobilized Myrica rubra tannin to Th(IV) is significantly higher than that of immobilized larch tannin, probably due to the fact that the B ring of Myrica rubra tannin has a pyrogallol structure which has higher reaction activity with metal ions. The breakthrough point of the adsorption column of immobilized Myrica rubra tannin was at 33 bed volumes for the experimental system. The mass transfer coefficient of adsorption column determined by Adams-Bohart equation was 1.61·10^-4 l·mg^-1.min^-1. The adsorption column can be easily regenerated by 0.1 mol·l^-1 HNO₃ solution, showing outstanding ability of concentrating Th(IV). This revised version was published online in July 2006 with corrections to the Cover Date.     

An efficient and general method for resolving cyclopropene carboxylic acids

A general method is described for the resolution of cycloprop-2-ene carboxylic acids via diastereomeric N-acyloxazolidines prepared from enantiomerically pure oxazolidinones. Although a number of oxazolidinones were shown to resolve cyclopropene carboxylic acids, the oxazolidinones of S-phenylalaninol, S-phenylglycine and (1S,2R)-cis-1-amino-2-indanol are optimal in terms of resolving power and cost effectiveness. Separations were performed using simple flash chromatography, and because there is typically a large difference in R_f values it is possible to separate gram quantities of pure diastereomers in a single chromatogram. The cycloprop-2-ene carboxylic acids that can be resolved include those that are substituted at the 1-position by H, Ph, α-naphthyl, CO₂Me, CH₂OMOM, and trans-styryl; alkene substituents include Me, n-alkyl, Ph and tethered alkynes. Remarkably, 2-methyl-3-propylcycloprop-2-ene carboxylic acid can also be resolved with ease. The relative configurations of four diastereomerically pure oxazolidines were determined by X-ray crystallography. Reduction of the N-acyloxazolidinones with LiBH₄ give enantiomerically pure derivatives of 3-hydroxymethylcyclopropene that react with either MeMgCl or vinylMgCl and catalytic CuI to give enantiomerically pure products of syn-addition.     

葡萄糖、果糖和蔗糖在甲酰胺溶液中的体积性质

报导了含葡萄糖、果糖和蔗糖的甲酰胺溶液的密度数据，无限稀释表观摩尔体积和体积第二维里系数．利用改进的定标粒子理论、基团几何模型和基团加合方法，求解了溶质的空腔生成体积，溶质-溶剂间的氢键作用对体积性质的影响，并和水溶液中的情况进行了比较．     

Synthesis and magnetic properties of trinuclear copper(II) complexes bridged by dimethylglyoximate groups

Summary New three Cu^II-Cu^II-Cu^II homotrinuclear complexes have been synthesized, namely [Cu(dmg)₂{CuL}₂](ClO₄)₂ [L = 5-nitro-1,10-phenanthroline (5-NO₂-phen), 4,4-dimethyl-2,2-bipyridiine (DMbpy), tetramethylenediamine (TMDA) and dimethylglyoximate ion (dmg)^2-]. The magnetic susceptibilities of complexes (1) (L = 5-NO₂-phen) and (2) (L = DMbpy) were measured in the 4.2–300 K range, giving the parameters,J = -335cm^-1 (1) andJ= -327.5cm^-1 (2). The results demonstrate a very strong antiferromagnetic exchange interaction between the adjacent copper(II) ions.     

Theory of solid solubility for rare earth metal based alloys

Both parabola and ellipse separating schemes are used to study the solid solubilities for the binary alloy systems based on the 13 rare earth metals. It has been found that the soluble elements can be separated from the insoluble ones by a parabolyy ₁=a?bx ₁ ² or an ellipse(x ₂?m)²/c²+(y₂?n)²/d²=1. The results show that the overall reliabilities of the solid solubilities for the 897 binary alloys based on the rare earth metals are 89.2% and 92.8% for the parabola and ellipse regularities respectively. The constants a and b in the parabola equation, andm, n, c andd in the ellipse equation are discussed, which can be related to some appropriate parameters for each host metal respectively.