Crystal structure and mechanism of (Z)-1-[2-(phenyl-bromide-chloride)vinyl]-1-cyclohexanol

The crystal structure and mechanism of the title molecule are described. This crystal is orthorhombic, belonging to space group PC21/B with a=1,002 1(2) nm, b=1.483 0(3) nm, c=2.173 6(4) nm, V=3.230 39(2) nm(3), Z=2, D-c=1.80 g/cm(3), R=0.069 3. The structure was solved by direct method. The tin atom of the title compound exists in two distorted-trigonal-bipyramidal geometry, defined by two carbon, one bromide, one chloride and one oxygen atoms leading to a five-membered chelate ring. In the structure, the five-membered ring containing the intermolecular O-->Sn has a half chair conformation.

Magnetic and magnetotransport properties of intermetallic SmMn2Si2

The magnetic properties of naturally layered intermetallic compound SmMn2Si2 with textured structure have been studied. There exist a ferromagnetic transition at 35 K and two antiferromagnetic transitions at 120 and 230 K. The antiferromagnetic state below 230 K exhibits different magnetoresistance, with a negative magnetoresistance of 3%-4% for current I applied perpendicular to the c axis and with a positive magnetoresistance effect of about 4%-6% for current I parallel to the c axis. The observed magnetoresistance is likely to be related to magnetovolume effects. In the ferromagnetic state, a positive magnetoresistance with a maximum increase of 22% under an applied field of 5 T is observed at 4 K, and both H perpendicular to I and H parallel to I configurations show positive magnetoresistance. (C) 1997 American Institute of Physics.

流动注射化学发光检测法的进展

评述了近年来流动注射化学发光检测法及生物发光检测法的最新进展。内容涉及各类化学发光反应、生物发光反应和电致化学发光反应同流动注射体系的耦合方式，仪器设计，多种无机、有机、生物大分子、生物活性物质及药物的分析方法及其在环境、生物医学科学和生命科学、临床化学及药物化学中的应用和发展方向，引用文献124篇。

MODIFIED POLYSULFONES .1. SYNTHESIS AND CHARACTERIZATION OF POLYSULFONES WITH UNSATURATED END-GROUPS

Chloro-terminated polysulfones with various molecular weights were modified with poly(ethylene oxide) and poly[(ethylene oxide)(propylene oxide)] macromers carrying alpha-hydroxyl and omega-allyl end groups via classical polycondensation reactions. The pr

结晶聚合物的单轴拉伸和取向态结构 Ⅰ 拉伸结晶聚合物的形变机理

本文综述了关于拉伸结晶聚合物形变机理的研究工作,重点介绍了拉伸聚合物在形成细颈过程中,从原来的球晶(或堆积片晶)结构向纤维结构的转化过程,以及有关这一形变过程。目前存在的不同观点及各方面的实验证据。指出拉伸结晶聚合物的形变机理可能依赖于拉伸条件。

SYNTHESIS, THERMAL-STABILITY AND X-RAY CRYSTAL-STRUCTURE OF THE BIS(CYCLOPENTADIENYL)YTTERBIUM NAPHTHOXIDE DERIVATIVE (C5H5)2YB(OC10H7)(THF)

Cp3Yb (Cp = C5H5) reacts with a-naphthol (HNP) in THF to form Cp2Yb(NP)(THF) (1), which crystallizes in the space group P2(1)/n with unit cell dimensions a = 8.084(2), b = 15.996(6), c = 15.973(7) angstrom, beta = 98.95(3), V = 2040.3 angstrom and D(calc.) = 1.69 g cm-3 for Z = 4. Least-squares refinement based on 2242 observed reflections converged to a final R value of 0.081. The average Yb-C(Cp) distance is 2.60(2) angstrom and Yb-O(THF) and Yb-O(NP) distances are 2.30(1) and 2.06(1) angstrom, respectively. The title compound loses the coordinated THF molecule readily by heating under vacuum to give dimeric [Cp2Yb(NP)]2 (2), which undergoes disproportionation to give Cp3Yb and Yb(NP)3 on heating above 230-degrees-C.

SYNTHESIS AND MOLECULAR-STRUCTURE OF THE 5-COORDINATE ZIRCONIUM COMPLEX (CH3C5H4)2ZRCL(ALPHA-C10H7COO)

Bis(methylcyclopentadienyl)chloro(alpha-naphthoyloxy)zirconium, (CH3C5H4)2Zr Cl(alpha-C10H7COO), has been synthesized by the reaction between (MeCp)2ZrCl2 and equimolar sodium alpha-naphthoate in toluene at room temperature. The molecular structure of the title complex was determined by X-ray diffraction. The molecules have a five-coordinate bent metallocene structure in which the alpha-naphthoxyligand is bidentate [Zr-O, 2.317(2), 2.260(2) angstrom]. The remaining distances are [Zr-Cl, 2.521(1) angstrom; Zr-C, 480-2, 565 angstrom; Zr-cent-CH3C5H4 2.217 and 2.230 angstrom].

STUDY OF THE CHLORINATION REACTION OF Li2CO3 WITH NH4Cl

The chlorination reaction of Li2CO3 with NH4Cl has been studied in detail by a series of thermal analysis methods. When NH4Cl/Li2CO3 mole ratio equals 4, Li2CO3 can be transformed into LiCl quantitatively in a stream of Ar gas flow. All residual NH4Cl is decomposed completely at 400 degrees C and carried away from the reaction cell by Ar gas.Analysis by X-Ray diffraction and Ion Chromatography show that there are almost no NH4Cl remained in The LiCl product. It is interested that the chlorination reaction can be applied to the determinations of phase diagram by thermal analysis method and the preparation of Al-Li alloy by electrolysis in molten salt.

PMMA-PEO共混体系的辐射交联

聚甲基丙烯酸甲酯(PMMA)是典型的辐射裂解型聚合物。经辐照后,PMMA主链发生无规断裂。在聚合物共混体系中,PMMA是否能发生交联,这是辐射化学中一个非常重要的研究课题之一,也是一项探索性工作。 PMMA-PEO共混体系是可以分子水平共溶的体系。本文试图将共混体系的相容性与共混体系中的裂解型聚合物的辐射效应联系起来,讨论PMMA-PEO共混体系的辐射交联。

饱和水溶液的膜蒸馏——从废液回收牛磺酸的实验研究

非挥发性溶质的水溶液能够用膜蒸馏技术浓缩到饱和状态,如果溶质是容易结晶的物质,在饱和水溶液膜蒸馏过程中就会出现膜蒸馏——结晶现象,用膜过程直接从水溶液中分离结晶产品的可能性被实现了。本文采用氯化锂代替水溶性高分子作添加剂,以相转化法制备了聚偏氟乙烯中空纤维膜,疏水性得到明显的改善,用于处理牛磺酸废水,得到结晶产品,展示了膜蒸馏技术处理工业废水的光明前景。

磁共振成像用造影剂的合成

总结并评论了造影剂的合成方法,还列表给出了造影剂的特性和应用。

五取代茂基稀土配合物-活性碱金属氢化物催化的烯烃加氢反应

提出了一类以五取代茂基稀土金属配合物与活性碱金属氢化物组成的加氢催化体系。实验表明:(C_5Me_4R)_2LnCl_2Li(THF)_2+MH(Ln=Nd,Yb,R=Pr;Ln=Gd,R=Me,Pr;M=K,Na)体系都能催化α-烯烃加氢,其活性较高,如(C_5Me_5)_2GdCl_2Li-NaH体系对1-己烯加氢TON可达40min~(-1)。碱金属氢化物的种类、THF以及温度等对其催化活性均有不同的影响。这类催化剂失活很快,其原因与反应体系中的烯烃有关。

希土永磁材料Nd—Fe—B氧化过程及抗氧化新体系的研究

Nd-Fe-B永磁体的热稳定性较差,易氧化,氧化使材料的结构受到破坏,永磁性能受到不可恢复的损失。氧化过程是分阶段的,在室温和干燥的空气中是稳定的,150℃左右受到破坏的主要原因是体系中钕的氧化,230℃以上铁开始氧化,温度升高使氧化加快,800℃左右氧化基本结束,最终产物主要是Fe_2O_3、Nd_2O_3和NdBO_3。新研制的Nd-Fe-B-Si四元体系的抗氧化能力有较大的提高,居里温度也提高了许多,是一种大有发展前途的新材料。

二(2-乙基己基)膦酸萃取Er(Ⅲ)的动力学和机理

H(DEHP)是HEH(EHP)和HDEHP的同系物,它们的结构分别为:HDEHP,(GO)_2PO(OH);HEH(EHP),(GO)(G)PO(OH);H(DEHP),(G)_2PO(OH)。其中G为2-乙基已基。 希土元素萃取分离工艺化学表明,溶剂萃取希土元素对酸度的依赖关系及相邻希土元素间的分离因素值是选择萃取剂时应优先考虑的因素。HDEHP萃取剂对中、重希士元素反萃酸度高,HEH(EHP)是一个优良萃取剂,但对Er,Tm,Yb,Lu的反萃仍需5mol/l的酸。由于H(DEHP)分子中不含酯氧原子,使得它的pK_a值比HDEHP和HEH(EHP)的高。从而,用H(DEHP)萃取希土元素时需要的水相酸度更低,反萃更容易。而且H(DEHP)