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1.
聚甲基丙烯酸4[(4'-硝基-1'硫酰基苯)-1-羟烷氧基本基]酯的合成张维邦,蒋,许家瑞,曾汉民(中山大学材料科学研究所广州510275)关键词含硫液晶单元,侧链液晶高分子,液晶合成与表征侧链高分子液晶是高分子液晶的重要组成部分,是当前高分子科学中...  相似文献   

2.
马汝建  李培 《应用化学》1997,14(6):63-65
手性液晶掺杂剂(S)┐4┐辛氧基┐4┐(2┐酰氧基┐丙氧基)联苯的合成马汝建李培荣国斌*(华东理工大学化学系上海200237)关键词铁电液晶材料,手性液晶掺杂剂,合成,手征性1997-02-03收稿,1997-08-07修回铁电液晶显示器所用的材料...  相似文献   

3.
聚甲基丙烯酸4[(4’-烷氧酰基—1’—疏酰基苯)-1-羟乙氧基苯基]酯的合成张维邦,蒋,许家瑞,曾汉民(中山大学材料科学研究所广州510275)关键词侧链液晶高分子,含硫液晶单元液晶的合成侧链高分子液晶是高分子学科中非常活跃的研究领域“’,其特点是...  相似文献   

4.
1,2,4-三嗪类化合物的研究(ⅩⅫ)──咪唑并-(5,4-e)-1,2,4-三嗪衍生物的合成沙耀武,蔡孟深(北京医科大学药学院,北京,100083)关键词乙二脒腙,原甲酸三乙酯,1,2,4-三嗪,咪唑并-(5,4-e)-1,2,4-三嗪天然碱基拮抗...  相似文献   

5.
1-(1-H-苯并三唑-1-乙酰基)-4-(邻氯苯甲酰基)氨基硫脲(Ⅴ)及其噻二唑衍生物(Ⅵ)的合成魏太保,陈继畴,张有明,李清河,陈真吉(西北师范大学化学系,兰州730070)三唑类化合物是一类新型的植物生长调节剂。这类化合物能够控制植物生长,增加...  相似文献   

6.
以4'-羟基联苯为原料合成了8种新型4'-酰基-4-羟基联苯酯类化合物.除化合物5_h外,均为新的近晶相液晶化合物.它们具有较宽的相变温度范围和较高的热稳定性.用偏光显微镜和差热分析仪研究了它们的相行为,讨论了分子结构对液晶相行为的影响.  相似文献   

7.
铕(Ⅲ)-β-二酮-4,4'-联吡啶-N,N'-二氧化物三元配合物的合成与表征林惠文,朱文祥(海南师范学院化学系,海口,571158)(北京师范大学化学系,北京,100875)关键词铕(Ⅲ),4,4'-联吡啶-N,N'-二氧化物,β-二酮,三元配合物...  相似文献   

8.
2-(3,4,5-三甲氧基)苯基-4,9-二氢环庚并吡喃-4,9-二酮的一步合成高文涛(锦州师范学院化学系锦州121003)关键词缩杂环酮化合物,3,4,5-三甲氧基,苯甲醛,成环缩合,合成自然界中某些抗菌素和毒菌的基本组成中含有酮结构单元,具有抗癌...  相似文献   

9.
Zn_2Al-PW_(12-n)V_nO_(40)(n=1~4)的合成与表征郭军,孙铁,沈剑平,蒋大振闵恩泽(吉林大学化学系,长春,130023)(石油化工科学研究院)关键词P-W-V杂多阴离子,柱撑水滑石,合成同多和杂多阴离子柱撑水滑石(简称POMs-...  相似文献   

10.
4-羟基-2,5-二甲基-3(2H)呋喃酮的合成   总被引:3,自引:0,他引:3  
总结了食品增香剂4-羟基-2.5-二甲基-3(2H)呋喃国的合成方法,包括近期的合成研究进展,对一些合成方法的优缺点作了评述。参考文献28篇。  相似文献   

11.
The crystal structure of LaIr4B4 has been refined from single crystal counter data. LaIr4B4 is tetragonal,P42/n,Z=2, isotypic with NdCo4B4, |F|/|F o|=0.039 for 312 independent reflections [|F o|>2 (F o)]. ThIr4B4 and ThOs4B4 also belong to the NdCo4B4-type structure. URu4B4 and UOs4B4 were found to crystallize with LuRu4B4-type structure. The crystal chemistry of (RE)T 4B4-phases is discussed and simple geometric relations are shown to exist between them.Dedicated to Prof.B. T. Matthias in celebration of his 60th birthday.  相似文献   

12.
Die erstmals dargestellten isotypen Verbindungen Ba4SiAs4, Ba4GeAs4, Sr4SiAs4 und Sr4GeAs4 kristallisieren kubisch, Raumgruppe P4 3n, mit 8 Formeleinheiten in der Elementarzelle: In den Strukturen liegen isolierte, d.h. nur von Ba-Ionen umgebene SiAs - bzw. GeAs -Tetraeder vor. Die Verbindungen sind die bisher eindrucksvollsten Beispiele für Zintlphasen mit komplexen Anionen. Zintl Phases with Isolated SiAs4 or GeAs4 Anions: Preparation and Structure of Ba4SiAs4, Ba4GeAs4, Sr4SiAs4, and Sr4GeAs4 The new compounds Ba4SiAs4, Ba4GeAs4, Sr4SiAs4, and Sr4GeAs4 have been prepared and their structures determined. They crystallize in the cubic system, P4 3n, with axes: data see “Inhaltsübersicht”. There are isolated SiAs or GeAs tetrahedra in the structures. The compounds can be interpreted as Zintl phases with complex anions.  相似文献   

13.
Vibrational Spectra of As4S4 and As4Se4 The vibrational spectra of solid α- and β-As4S4 and the Raman spectrum of molten As4S4 have been recorded. The assignments of the frequencies are proposed mainly based on polarization data. The Raman melt spectra suggest that As4S4 molecules (symmetry D2d) are retained in the molten state. A partial decomposition of the melt by prolonged laser irradiation was observed. The Raman spectrum of solid As4Se4 is presented and the frequencies are tentatively assigned to an As4Se4 molecule of the cradle type, possessing D2d symmetry.  相似文献   

14.
Hamad Z Alkhathlan 《Tetrahedron》2003,59(41):8163-8170
Cyclization of 2-hydroxyacetophenone hydrazones with triphosgene resulted in the formation of 4-methylene-1,3-benzoxazinones. These compounds were converted to 4-alkoxy-4-methyl-1,3-benzoxazinones and 4-fluoromethyl-4-methoxy-1,3-benzoxazinones upon treatment with alcohols under refluxing conditions and F-TEDA-BF4 in acetonitrile and methanol, respectively.  相似文献   

15.
Ab initio calculations have been performed on B4H4, B4Cl4 and B4F4 in order to aid our understanding of the bonding in these compounds, which is presumably based on a tetrahedral boron cage. This cage has only 8 electrons and so is less than that expected on the basis of the usual framework electron counting rules. Basis sets with polarisation functions were used at the SCF, CI and CPF levels of theory to confirm that the T d structures are indeed more stable than the D 4h ones. Davidson-Roby population analyses were able to show that many factors, including 3-centre 2-electron bonding and backbonding from the ligand to the boron cage, are of importance in determining the relative stability of the three compounds, of which B4Cl4 is the only one that has yet been observed experimentally.  相似文献   

16.
K4PbO4 and K4GeO4 — a Comparison The question is: In which case are two compounds isotypic? The structures of K4PbO4 and K4GeO4 are derived using ?Schlegelprojektionen”? (reduced atomic distances and angles) and ?Erweiterte Schlegeldiagramme”? of the anions: O1, O2, O3 and O4. The difference is pointed out and discussed. For both compounds the interatomic distances are listed.  相似文献   

17.
On K4PbO4 and Rb4PbO4 For the first time single crystals of K4[PbO4] have been prepared by heating K4PbO3 in O2. The structure has been refined [K4[PbO4]: 3029 I0(hkl), four circle diffractometer PW 1100, ω-scan, MoKα, R = 6.73%, Rw = 6.64%, P1 ; a = 658.62(15), b = 658.41(12), c = 986.64(21) pm, α = 79.74(2)°, β = 108.45(2)°, γ = 112.49(2)°, dx = 3.79 g · cm?3, dpyk = 3.78 g · cm?3, Z = 2; Rb4[PbO4]: a = 686.94(18), b = 684.43(18), c = 1020.73(21) pm, α = 79.28(2)°, β = 108.40(2)°, γ = 113.02(2)°, dx = 4.87 g · cm?3, dpyk = 4.85 g · cm?3, Z = 2, (from Rb2PbO3 and Rb2O)]. Both compounds are isotypic with K4SnO4. The Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated.  相似文献   

18.
《Liquid crystals》1997,23(1):9-16
Two families of liquid crystalline compounds have been synthesised, the 4-butyl-4- alkoxyazobenzenes and the 4-pentyl-4-alkoxyazobenzenes; for the second family results are presented for the first time for alkoxy chains longer than butyl. The results for both families have been obtained up to the octadecyl homologues. In both families, on the basis of DSC, polarizing microscopy and thermo-optical analysis, a rich polymorphism has been detected (maximum tetramorphism). The smectic properties start with the hexyl derivative (for the butyl family) and with the heptyl derivative (for the pentyl family). Strong odd-even effects for the temperatures of clearing in both groups of compounds were detected. Our results are compared with those of de Jeu et al. and of Adomenas et al. for the 4-butyl-4- alkoxyazobenzenes, for which only one smectic modification was described.  相似文献   

19.
The phase equilibria as well as the properties and crystal structures of the compounds formed in both Li2SO4-MgSO4 and Li2SO4-Li4SiO4 systems have been studied by means of x-ray diffraction technique (at high and room temperatures) as well as by the thermal analyses (DTA, DSC, TGA, etc.). In Li2SO4-MgSO4 system there exists a compound Mg4Li2(SO4)5 formed by peritectic reaction at 840°C and decomposed at 105°C into the Li2SO4-base solid solution and MgSO4 · Mg4Li2(SO4)5 and Li2SO4-base solid solution conduct an eutectic reaction at 663°C with the composition of eutectic point lying in 22 mol% MgSO4. The solubility of MgSO4 in Li2SO4 is a little smaller than 10 mol% while at the same time the Li2SO4 phase transition temperature decreases from 574 to 560°C On the other hand, no noticeable solid solubility of Li2SO4 in MgSO4 has been observed. The reaction is an endothermal one and its heat of formation is 2.57 kJ/mol. The activation energy of the reaction calculated by thermal peak displacement method at various heating rates is 173.5 kJ/mol (1.80 ev). The crystal Mg4Li2(SO4)5 belongs to orthorhombic system with lattice parameters at 180°C: a = 8.577, b=8.741, c= 11.918 Å. The space group seems to be either P222 or P mmm. Assuming that there are two formula units in a unit cell, the density calculated is then 2.20 g/cm3 very close to that of Li2SO4 or MgSO4. Meanwhile, in Li2SO4-Li4SiO4 system a new phase Li8-2x(SiO4)8-x(SO4)x is formed by peritectic reaction at 953°C with a range of composition x=0.96 ?0.58. The crystal belongs to ortho-rhombic system with lattice parameters at x=0.8: a = 5.002, b= 6.173 and c=10.608Å. The density observed is 2.31 g/cm3 and there are 2 formula units in an unit cell. It is shown from the measurements of piezoelectric and laser SHG coefficients of the crystal that the crystal posseses a symmetrical center with the space group belonging to P mmn. The lattice parameter c has a maximum at x=0.8. In the air Li8-2x(SiO4)2-x(SO4)x can absorb 7.6 wt% water vapour and other gases which can only be desorbed by heating it at a temperature above 350°C. Neither absorption nor desorbtion can change its crystal structure, a characteristic similar to that of zeolite molecular sieve. The dewater activation energy of Li8-2x(SiO4)2-x(SO4)x is 171.5 kJ/mol. Li8-2x(SiO4)2-x(SO4)x and Li4SO4 bring about an eutectic reaction at 823°C with its eutectic composition being 12 mol% Li4SiO4. No observable solubility of Li4SiO4 in Li3SO4 has been noticed. The solubility of Li2SO4 in Li4SiO4 is approximately equal to 5 mol%. With Li2SO4 being dissolved in, the phase transition temperature of Li4SiO4 is decreased. After being fused, the specimens Li3SO4-MgSO4 and Li2SO4-Li4SiO4 are cooled at a rate of 10°C/min, their metastable eutectic systems are resulted respectively.  相似文献   

20.
5-Methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones were condensed with 2-aminobenzenethiol or 6-substituted-3-aminopyridine-2(1H)thiones 4 to produce a new type of 5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-ones or 8-substituted-7-aza-5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-one derivatives. From 6-bromo-2,5-dimethyl-1,3-diphenyl-2H-isoindole-4,7-dione and 4 8-substituted-7-aza-2,5-dimethyl-1,3-diphenyl-4H-pyrrolophenothiazin-4-one derivatives were also prepared.  相似文献   

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