New pentacyclic ring systems: intramolecular cyclization of o,o′-disubstituted bibenzothiazoles

Efficient methods for the preparation of isomeric o,o′-diaminobibenzothiazoles (8a and 11a) and o,o′-diamino-2,2′-dimethylbibenzothiazoles (8b and 11b), potentially valuable building blocks for construction of hitherto unknown dithiazolo annulated pentacyclic heterocycles, have been developed. The dithiazolo annulated benzo[c]cinnolines 9a, 9b, and 12a were prepared from the corresponding diamines by oxidation with PhI(OAc)₂ in good yield. The dithiazolo annulated carbazoles 13 and 14 were efficiently prepared from the corresponding diamines by thermal cyclization in H₃PO₄. The unusual course of reduction and product formation of o,o′-dinitrosubstituted bibenzothiazoles 6a and 6b with SnCl₂ under acidic conditions was rationalized by DFT quantum-mechanical calculations. It was suggested that cyclic products are formed from dinitroso derivatives and open-shell species immediately following on a reduction path.     

Metal Exchange Reactions of o,o′-Dihalosubstituted Cd(II) Tetraphenylporphyrinates with d-Metal Salts in DMF

Russian Journal of General Chemistry - The metal exchange reactions of Cd(II)-5,10,15,20-tetra(2,6-dichlorophenyl) porphyrin and Cd(II)5,10,15,20-tetra(2,6-difluorophenyl) porphyrin with Zn(II) and...     

SOLUBLE POLY-(o, m)-TOLUIDINE

The soluble poly-o-toluidine (POT) and poly-m-toluidine (PMT) have been success-fully prepared under controlled conditions of polymerization and post-treatment, andcharacterized by IR, VPO and elemental analysis. It is found that the soluble and insol-uble polymers obtained with two different methods (Ⅰ and Ⅱ) have the similar conduc-tivity and molecular chain structure. VPO measurement shows that the number averagemolecular weight (Mn) of soluble polymers is about 3000. The mole ratio of benzoidto quinoid is about 3:1 according to ~1H-NMR and elemental analysis. Free-standingfilms of intrinsic POT and PMT have been obtained by casting their CHCl_3, THF orDMF solutions onto a glass surface.     

Synthesis,Spectral Characterization,and Crystal Structure of Two Polymorphs of o,o’-Dichloro Dibenzyl Disulfide

2-Chlorophenyl methanethiol undergoes air oxidation catalyzed by different selenides and yields the corresponding disulfide 1 in two polymorphic forms, 1a and 1b. In the molecular structures of the two new polymorphs of o,o′-dichloro dibenzyl disulfide, the dihedral angles between the dibenzyl groups are 82.0(1)°, (1a), and 73.7(4)°, (1b), respectively [(1a): P-1, a = 8.424(2) Å, b = 8.838(2) Å, c = 10.5823(19) Å, α = 90.122(18)°, β = 112.19(2)°, γ = 95.19(2)°, V = 725.9(3) ų; (1b): P2₁/n, a = 10.5888(10) Å, b = 9.1590(6) Å, c = 15.2489(14) Å, β = 103.072(9)°, V = 1440.6(2) ų]. MOPAC computational studies yield dihedral angles of 89.6(5)° and 71.9(9)°. Crystal packing is stabilized by weak π-ring (C?H···Cg) intermolecular interactions in both 1a and 1b and by additional weak Cg ··· Cg intermolecular interactions in 1b, which influence the bond distances, bond angles, and torsion angles of the dibenzyl groups in each polymorph. Additional characterization of each polymorph has been carried out by TEM, IR, ¹H and ¹³C NMR spectroscopy, microanalysis, and by FAB mass spectrometry. TEM studies of a sample of 1a show that it contains cigar-shaped crystallites.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

A General Chemical Method for the Stereochemical Analysis of Nucleoside-5′ [16o,18o] Phosphorothioates

Abstract

A simple chemical method of configurational analysis is presented which will facilitate stereochemical investigation of any restriction endonuclease enzyme reaction.     

Effect of aqueous and ethanolic extracts from pinhão coats on the properties of corn and pinhão starches

Journal of Thermal Analysis and Calorimetry - The Araucaria angustifolia seed, named pinhão, has a high content of carbohydrates, and it is considered an unconventional starch source. Its...     

Chromaticity characteristics of binary and ternary molybdenum(vi) complexes with o,o’-Dihydroxyazo and heterocyclic azo compounds

The chromaticity characteristics of molybdenum(VI) complexes with o.o’-dihydroxyazo compounds (Lyumogallion IREA and Magnezon IREA) and heterocyclic azo compounds [4-(2-pyridylazo)resorcinol and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol] were studied in the presence and in the absence of the third component, hydroxylamine. It was demonstrated that chromaticity characteristics can be used for analyzing samples with low molybdenum concentrations. The calibration graph equations for the color characteristics of complexes both in solution and in the immobilized exhibit sensitivity coefficients more than an order of magnitude higher than for absorbance and the Kubelka-Munk function     

A NOVEL PREPARATION OF o－ETHOXYPHENOL FROM o－CHLOROPHENOL IN THE PRESENCE OF PHASE TRANSFER CATALYSIS UNDER MICROWAVE IRRADIATION

ＡＮＯＶＥＬＰＲＥＰＡＲＡＴＩＯＮＯＦｏ－ＥＴＨＯＸＹＰＨＥＮＯＬＦＲＯＭｏ－ＣＨＬＯＲＯＰＨＥＮＯＬＩＮＴＨＥＰＲＥＳＥＮＣＥＯＦＰＨＡＳＥＴＲＡＮＳＦＥＲＣＡＴＡＬＹＳＩＳＵＮＤＥＲＭＩＣＲＯＷＡＶＥＩＲＲＡＤＩＡＴＩＯＮＹｕＬｉｎＪＩＡＮＧ；Ｊ...     

o／o型单核铁（Ⅲ）卟啉二聚体模拟细胞色素P450酶催化环已烷羟化？…

合成和表征了一系列以柔韧烷氧链相连的ｏ／ｏ型单核铁卟啉二聚体,利用Ｘ－光电子能谱（ＸＰＳ）研究了卟啉二聚体中由自由卟啉环向铁卟啉环发生的分子内电子转移,考察３了在以分子氧为氧源还原剂存在的温和条件下,该类配合物模拟细胞色素Ｐ４５０酶对环已烷羟化反应的催化性能。结果表明,该系列ｏ／ｏ莳的卟啉二聚体的催化性能明显优于相应的铁卟啉单体ＦｅＴＰＰＣｌ。随着烷氧链的增长,催化活性次序为：Ｃ２〉Ｃ４〉Ｃ６〉Ｃ     

Molecular structure and conformations of a sterically hindered aryl derivative of 1,3,4-oxadiazole containing an o,o′-biphenyl ring system

The structure of sterically hindered molecules of 2,2-bis(5-phenyl-1-,3,4-oxadiazol-2-yl)biphenyl has been studied. Crystals that are suitable for x-ray diffraction analysis can be obtained for the different conformers of this compound. It has been found that during synthesis the molecule of this compound is obtained in an energetically less favorable conformation. On the basis of model calculations using the AMI method with geometry optimization it has been proposed that during synthesis there are no changes in conformation of either the intermediates or the final product and the conformation of the resulting oxadiazole system is governed by the conformation of the initial 2,2-diphenic acid dichloride.Khar'kov State University, Khar'kov 310077. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 984–991, July 1996. Original article submitted April 23, 1996.     

可溶性聚(o—,m—)甲苯胺

本文通过控制聚合和后处理条件,首次合成了可溶性聚(o-,m-)甲苯胺,用IR,NMR,VPO和元素分析等手段表征了可溶聚合物。结果表明,按两种方法制备的可溶与不溶聚合物具有相同的电导率和链结构。可溶聚合物主链中含有约28个单体单元,苯式(B)与醌式(Q)的比例约为3:1。并由可溶聚合物制备了自支撑膜,掺杂了的自支撑膜具有与粉末同样的电导率和环境稳定性。     

M(o)bius环并苯的分子对称性

一般来说,点群理论认为M(o)bius带环分子最高的对称性只能是C2.本文讨论了由18个苯环组成的环并苯的异构体分子,包括柱面的Hückel型分子(HC-[18])和扭转180°的M(o)bius带环分子(MC-[18]).结果表明除了点对称性外,M(o)bius带环分子还存在一种可称为环面螺旋旋转(TSR)变换的对称性,为此还引用了环面正交曲线坐标系.此外,还讨论了这些分子关于TSR对称性匹配的原子集和原子轨道(AO)集.根据TSR对称性的循环群特征,可以建立此类群的不可约表示及有关特征标.这类分子的分子轨道(MO)关于TSR群的不可约表示是纯的,然而所含的相应的原子轨道对称性匹配的线性组合(SALC-AO)成分可以是多种的.     

o/o 型单核铁(Ⅲ)卟啉二聚体模拟细胞色素P450酶催化环己烷羟化的反应性能研究

合成和表征了一系列以柔韧烷氧链相连的o/o型单核铁卟啉二聚体. 利用X-光电子能谱(XPS)研究了卟啉二聚体中由自由卟啉环向铁卟啉环发生的分子内电子转移. 考察了在以分子氧为氧源还原剂存在的温和条件下, 该类配合物模拟细胞色素P450酶对环己烷羟化反应的催化性能. 结果表明, 该系列o/o型单核铁卟啉二聚体的催化性能明显优于相应的铁卟啉单体FeTPPCl. 随着烷氧链的增长, 催化活性次序为: C2>C4>C6>C8>C10. 该次序与单核铁卟啉二聚体的特定构象引起的立体位阻和分子内电子转移密切相关.     

电沉积nicocral2o3泡沫合金及其高温抗氧化性

用电沉积方法制备了NiCoCr-Al_2O_3泡沫合金,研究了镀液组分对泡沫合金组分的影响。结果表明,随着镀液中CrCl_3·6H_2O和Al_2O_3的增加,合金中Cr和Al_2O_3含量增加,Cr质量分数高于6．8％,镀层变黑, Al_2O_3质量分数高于8．1％时,合金变脆。合金只有在≥852．37℃热处理后形成了有利于高温抗氧化性的相态,在1 200℃热处理后,合金的高温氧化增重率最低。随着合金中Cr和Al_2O_3含量的增加,合金的高温抗氧化性提高,且Al_2O_3含量对高温抗氧化性影响更显著。     

Br(o)nsted酸性离子液体催化合成阿司匹林

用Brcnsted酸性离子液体[Hmim]BF4、[bmim]HSO4和[bmim]H2PO4代替浓H2SO4为催化剂催化乙酸酐对水杨酸的乙酰化，合成阿司匹林。考察了反应温度、反应时间、催化剂用量、酐／醇摩尔比对水杨酸酰化反应产率的影响和离子液体的重复使用性能。选择了最佳反应条件，以[bmim]H2PO4作为催化剂，催化剂用量为0．28g（1．18×10^-3mol），水杨酸2．762g（0．02mol），乙酸酐4．083g（0．04mol），n（酐）：n（醇）=2：1，反应时间30min，反应温度70℃，产率最高达63．43％，并且[bmim]H2PO4溶于水后通过过滤和旋蒸脱水，重复使用3次，产率无明显变化。     

Theoretical studies on fullerene C4o′s derivatives C4o X2 (X =H, F, Cl, Br)

应用密度泛函理论在B3LYP/6 31G*水平上对C40X2 (X=H,F,Cl,Br)进行研究.研究结果表明,C40X2 (X=H,F,C1,Br)在热力学上是稳定的,卤化衍生物的稳定性随卤素原子序数的增大而降低,最有利的衍生化方式是1-4加成,1-2与1-4加成的卤化和氢化衍生物在所研究的分子中较为稳定.这些研究有助于理解富勒烯衍生物的衍生化模式.     

薄层层析-光度法联用测定甲基对硫膦中o,o′-二甲基-对硝基苯基硫代膦酸酯

应用薄层色谱法(TLC)使对硫膦中的主成分,o,o′-二甲基-对硝基苯基硫代膦酸酯(DMNPTP),与以杂质共存的二硝基与邻硝基衍生物分离。TLC法中用硅胶(G254)作吸附剂,用石油醚与乙酸乙酯(8 2)的混合物作为展开溶剂,经TCL分离后,用刀片将样品(含DMNPTP)的色谱带括下,经蒸发除去有机溶剂,用硝酸-高氯酸加热消化并蒸发至干后,用硝酸溶解残渣。此时,溶液中原来以DMNPTP存在的化合物已转化为正磷酸盐,随即用磷钒钼杂多酸光度法测定其磷含量,测定波长为其吸收峰450 nm,由测定值换算为DMNPTP的含量。