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1.
煤中氢键类型的研究   总被引:8,自引:1,他引:7  
陈茺  李伟 《燃料化学学报》1998,26(2):140-144
采用真空红外光谱技术清晰地观察到了碳含量73-88w%的四个煤样及其溶剂抽出物中的五种羟基的不同氢键缔合类型,并通过原位热解红外光谱技术研究了它们的热稳定性。  相似文献   

2.
晶体中的C-H…O氢键   总被引:1,自引:0,他引:1  
时茜  唐宗薰 《大学化学》1999,14(1):32-35
介绍了晶体中的C—H…O氢键,包括其键长、键角以及C—H基团的酸性与O原子的碱性对C—H…O键长的影响及C—H…O氢键在晶体工程学中的作用。  相似文献   

3.
报道了配合物Eu(XnP)3.3H2O「其中X=H,2-Cl,3-OH,4-Br,3-NO2,2-OCH3,2-CH3,2,4-二氯;P=2-(COO)C6H4CONHC6H5-^-,n=1,2」的制备,并用元素分析,红外光谱,电子反射光谱,热重分析进行了表征。  相似文献   

4.
稀土二茂铁甲酸配合物的研究   总被引:1,自引:0,他引:1  
合成了15种稀土元素的二茂铁甲酸配合物,对其进行了元素分析、质谱、溶液电导、X-射线粉末衍射、付立叶红外光谱的研究。结果表明配合物的组成为:(η ̄5C_5H_5Feη ̄5C_5H_4COO ̄-)_3·Ln·H_2O,(Ln=La~Lu及Y,pm除外),且均为类质同晶化合物,COO ̄-都以螯合方式与Ln ̄(3+)配位,在红外光谱中观察到明显的“Ln系效应”。  相似文献   

5.
报道了配合物Eu(XnP)3·3H2O[其中X=H,2-Cl,3-OH,4-Br,3-NO2,2-OCH3,2-CH3,2,4-二氯;P=2-(COO)C6H4CONHC6H5-n-,n=1,2]的制备,并用元素分析,红外光谱,电子反射光谱,热重分析进行了表征。结果表明配位是通过羧酸基上氧原子和酰胺羰基氧原子进行的,含3分子水。通过电子反射光谱,对Nephelauxetic比率(B),平均共价参数(δ)和平均成键参数(b1/2)进行了计算,对配合物的共价成键情况进行了讨论。  相似文献   

6.
水/AOT/正庚烷微乳体系中水结构的FT-IR研究   总被引:4,自引:0,他引:4  
运用傅立叶变换红外光谱(FT-IR)对水/AOT/正庚烷微乳体系中水的微结构进行了研究。结果表明,随着体系中加水量的增大,水分子O-H伸缩振动的红外光谱由3493cm^-1向低频移动至3417cm^-1,微乳体系中,水分子与AOT分子的磺酸基作用的同时,与Na^+也有一定的作用,这两种离子对水分子O-H键的强度均有一定的影响,磺酸基的作用使水分子中O-H伸缩振动向高波数方向移动,而Na^+的作用与  相似文献   

7.
八烷氧基2,3-萘酞菁锌(Ⅱ)的合成及荧光光谱研究   总被引:1,自引:0,他引:1       下载免费PDF全文
采用在强有机碱1,8-二氮杂双环[5,4,0]+--7烯(简称DBU)存在下的醇溶剂中,由“分子碎片”与锌盐通过模板反应的新方法合成了一组八烷氧基2,3-萘酞菁锌配合物(Zn(RO)8NPc,其中R=C4H9、C8H17、C12H25,NPc=C48H16N8)。产物进行了元素分析和红外光谱分析,并研究了它们在不同溶剂中的荧光光谱。  相似文献   

8.
通过PGE和mPDA体系反应前后的近红外和中红外光谱图的对比,说明对于含N─H和O─H官能团的物质近红外光谱显示出中红外光谱无法比拟的优越性。本研究介绍了近红外光谱对N─H、O─H、CH_2─CH─等官能团分析的应用实例,以及如何应用近红外光谱法研究金属氧化物的表面羟基与其催化活性的关系。  相似文献   

9.
原位漫反射新方法研究煤中氢键的分解动力学   总被引:1,自引:0,他引:1  
采用一种新的原位漫反射红外技术研究了干燥脱灰褐煤中氢键的分解动力学,同时介绍并应用了一种防止高温下挥发分冷凝的原位漫反射红外实验方法。基于两条假设,当煤加热至560℃时,单一反应模型可以用于除OH-π键以外氢键分解动力学参数的求解。结果表明,煤中羧酸二聚体、OH-N 和SH-N三种氢键的分解动力学遵循二级反应;OH-OR2,紧密结合的羟基四聚体和自缔合的羟基多聚体则遵循一级反应。计算所得的几种氢键分解活化能与文献中采用其他 方法所得结果基本一致。在所考察的六种氢键中,羧酸二聚体、OH-N 、SH-N和紧密结合的羟基四聚体的分解可以分为两个阶段(230℃~380℃和 380℃~500℃),而OH-OR2和自缔合的羟基多聚体的分解可以按照一段来处理。另外,通过比较自缔合的羟基多聚体的分解活化能和文献中的氢键键能,获得了其分解机理。
  相似文献   

10.
本文应用“原位”发射红外光谱技术,在280℃,0.5MPa反应条件下,对于Cu/ZnO/Al2O3催化剂 CO+H2CO+H2+CO2反应体系的反应过程进行了动态跟踪结果表明,CO|H2反应体系中,CO插入表面-烷氧基的金属-碳键可能是生成碳二以上醇的反应速控步骤。  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

13.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

14.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

15.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

16.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

17.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

18.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).  相似文献   

19.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

20.
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.  相似文献   

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