DIELECTRIC PROPERTIES OF 1, 2-POLYBUTADIENES

The dielectric permittivity and loss tangent of 1,2-polybutadienes with different chain structures were determined as a function of temperature from-180℃ to 100℃ at different frequencies, and the frequency and structure dependence of the dielectric propertie of 1,2-polybutadienes have been investigated. It is found that a maximum of the permittivity occurs in the glass-transition region. The width of the glasstransition peak increases with increasing frequency while its height has little change. With a rise in the content of 1,2-units, the permittivity decreases and the height of the glass-transition peak slightly grows. A maximum of the width of the glass-transition peak appears when the content of 1,2-units is about 45%. Both the permittivity and dielectric loss drop down as the growth of the content of syndiotactic 1,2-units.     

Blends of Polypropylene and Syndiotactic 1,2-Polybutadiene:Morphology,Crystallization Behaviors and Mechanical Properties

Morphologies,crystallization behavior and mechanical properties of polypropylene（PP）/syndiotactic 1,2-polybutadiene（s-1,2 PB）blends were investigated.Morphology observation shows the well dispersed domains of s-1,2 PB in PP matrix with the rather small domain sizes from 0.1 to 0.5μm when the s-1,2 PB content increases from 5%to 20%（mass fraction）in the blends,and the phase structure tends to become co-continuous as s-1,2 PB content further increases.Crystallization temperature（Tc）of PP component in the blends is fluctuated with the variation of s-1,2 PB content in the blends.Compatibilization,to some extent,between the two components is inferred from the examination of both morphology and crystallization behavior.Improvement of impact strength of PP toughened by s-1,2 PB becomes significant only in the case of s-1,2 PB content above 20%（mass fraction）.     

Novel Three-Component Reaction Catalyzed by Dirhodium(Ⅱ) Acetate: Decomposition of Phenyldiazoacetate with Arylamine and Imine for Highly Diastereoselective Synthesis of 1,2-Diamines

A novel three-component carbon-carbon forming reaction is discovered. Reaction of methyl phenyldiazoacetate with both imine and arylamine in the presence of dirhodium acetate catalyst gives good yields of 1,2-diamines 5 in competition with N-H insertion to yield 4. While the product ratio is dependent on the electronic features from aryl substitution of the corresponding amine, diastereoselectivity of 5 was consistently high (greater than 10:1 ). Although N-H insertion is competitive, this pathway can be minimized by the use of excess imine. A plausible mechanism revealed that the key intermediate is proposed to be ammonium ylide. This discovery is useful for the preparation of 1,2-diamines with high diastereoselectivity.     

SYNTHESIS OF 1,2-ACEANTHRYLENEDIONE THROUGH ACYLATION OF ANTHRACENE WITH OXALYL CHLORIDE

Acylation of anthracene and oxalyl chloride in the presence of anhydrous AlCl3 was investigated. Pure 1,2-aceanthrylenedione, which is used as new functional macromolecule, was prepared by extraction and recrystallation. The structure of 1,2-aceanthrylenedione was identified by measure of melting point, GC/MS, FTIR and 1↑HNMR analyses. The influences of various parameters, such as solvent, dosage of catalyst, molar ratio of anthracene to oxalyl chloride, reaction temperature, and reaction time were studied. The anhydrous AlCl3 was found to catalyze the reaction with high yeild and good selectivity. When the reaction temperature is 303K, reaction time is 5h and molar ratio of anthracene to oxalyl chloride is 1：2, the yield and selectivity of 1,2-aceanthrylenedione is 83.8 % and 92.3% respectively.     

Mechanism of 1,2-shift through π-complex transition state

A systematic calculation of the potential curves or surfaces for 1,2-shift has been realized by using MNDO or other models in MOPAC programs. By referring to the previous authors' viewpoints, the 1,2-shift can be divided into two categories. 1,2-electron-deficient shift is that the electronic configuration of the atom which accepts the migrating group is a cation or an electron-deficient atom, and 1,2-anion shift is the one that the accepted atom of the migration group is a negative ion. In terms of the experimental facts and the calculation of the potential surfaces, in electron-deficient shift such as Beckmann or Baeyer-Villiger rearrangement, the migration occurs through a transition complex formed between the 7i-bond and the cation or electron-deficient migrating group, but in anion shift such as Wittig or Stevens rearrangement, the electron pair in it-orbit excites at first to π* orbit, and then the migration occurs through the new formed complex between the anion migration group and the vacant rc     

A NEW MODEL FOR ESTIMATION OF DIFFUSION COEFFICIENT OF PHENOL DESORPTION WITHIN POLYMERIC RESIN UNDER ULTRASOUND

1. INTRODUCTION Ultrasound is a kind of mechanical wave whose frequency is more than 20 kilohertz. It can enhance the mass transfer, increase the rate and conversion of chemical reaction, change the reaction pathway [1,2] and accelerate the conversion of…     

Study of the Electrical Double Layer of a Spherical Micelle: Functional Theoretical Approach

The electrical double layer theory is the base of the colloid stability theory (DLVO theory), and the PB eq. is a key to the study of the layer1,2. For a spherical particle, the PB eq. is (1) where and are the dielectric constant of the medium, the valence of ions, the elementary charge, the concentration of ions far away from the particle, the Boltzmann's constant and the temperature of the system, respectively. Since this eq. is a second order nonlinear differential one, only the anal…     

NaSO2Ph 催化下1，2-联烯亚砜高产率，高选择性异构化为炔基亚砜

The clean isomerization of 1,2-allenyl sulfoxides in the presence of NaSO2Ph afforded 2-alkynylic phenyl sulfoxides in good yields and selectivities. Although strong base-catalyzed isomerization of allenes to alkynes is known, the mechanism for the current reaction is interesting for the obvious reason that NaSOEPh is a weak base.     

Inhibition of the Crystal Growth and Aggregation of Calcium Oxalate by Algae Sulfated Polysaccharide In-vitro

Kidney stone disease causes substantial suffering and occasional renal failure. The content of calcium oxalate (CaOxa) is up to 70-80% in the stones1,2. However, the mechanism of the formation of urinary stones is not yet clearly understood and the questi…     

Synthesis of Meso-tetra(4-hydroxyl-3-sulfonate-phenyl) Porphyrin and Its Palladium(Ⅱ) Complex

Porphyrin is the core of haemachrome, cytochrome and chlorophyll and is known as an important compound related to life. The simulation of the haemachrome, cytochrome and chlorophyll in life with the artificial metalloporphyrin complex[1,2] is an active research area in recent years.     

Thermal reactions of oxiranes

The pyrolytic reactions of tetramethylethylene oxide, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, 1,2-epoxyethylbenzene, 1,2-epoxy-2-phenylpropane, 1,2-epoxy-1-phenylpropane, and 1,2-epoxy-1,2-diphenylethane were investigated at 600 °C using a conventional pyrolysis flow system. The products are mainly due to thermal cleavage of the oxirane ring followed by rearrangement to give carbonyl compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 946–949, May, 1995.The authors acknowledge the financial support from B. P. International for this project.     

碱催化促进Ni-W/β分子筛催化剂氢解纤维素产1,2-丙二醇的研究

为提高纤维素催化氢解产醇类产物中1,2-丙二醇(1,2-PG)的收率,采用等体积浸渍法制备了以β分子筛为载体负载Ni和W的催化剂。结果表明,当7Ni-20W/β分子筛作为催化剂时,在240℃反应温度和6.0 MPa H_2的条件下反应30 min后,纤维素实现完全转化,1,2-PG和乙二醇(EG)产率分别达到19.3%和45.3%;不同于其他载体催化剂,β分子筛可以明显提高1,2-PG选择性。当不同碱催化剂加入到Ni-W/β分子筛催化剂反应体系后,可以进一步提高1,2-PG的选择性。尤其是当加入Ba(OH)_2后,1,2-丙二醇产率从19.3%提高了32.5%。为了探究碱催化剂在反应中的作用,以葡萄糖为底物进行了一系列的碱催化反应。结果表明,碱催化剂主要作用是有助于将葡萄糖异构化为果糖,从而促进纤维素转化为1,2-PG。催化剂在两次回收重复利用之后1,2-PG的收率只下降3.9%,乙二醇产率收率下降4.1%。     

Asymmetric Direct Aldol Reactions Catalyzed by a Simple Chiral Primary Diamine–Br⊘nsted Acid Catalyst in/on Water

Abstract

The direct asymmetric aldol reaction catalyzed by the simple and commercially available chiral primary diamines, (1S,2S)-1,2-diphenylethane-1,2-diamine and (1R,2R)-1,2-diphenylethane-1,2-diamine, is presented. The catalyst system is a primary amine with Br?nsted acid–catalyzed direct aldol reaction of p-nitrobenzaldehyde and cyclohexanone with high chemo- and stereoselectivity on water, which furnishes the corresponding β-hydroxyketone with up to 94% ee.     

Solvent Effect of DMSO-d6 on 1,2-Diols in 1H NMR

There is a classic experiential rule about 1,2-diol RCR^1 （OH） CR^1 （OH） R（ R^1 = H or methyl）, that is, the proton chemical shift of the α-R^1 group at the hydroxvl group in the all-isomer, in general, aPPears in a higher field with ca.     

Fusopoltides B–E,new polyketides isolated from Fusarium solani B-18

Four new polyketides, fusopoltides B–E, were isolated, along with four known compounds, from Fusarium solani B-18 cultured on brown-rice. Fusopoltide B is a diastereomer of its co-isolated known compound, fusopoltide A, featuring a pentaleno[1,2-c]pyran ring system. Fusopoltide C and fusopoltides D–E are incorporated the first natural polyketides featured decahydro-pentaleno[1,2-c]pyran and pentaleno[1,2-c]furan ring systems, respectively. The structural assignments were established using comprehensive spectroscopic techniques, the modified Mosher's ester method, and electronic circular dichroism (ECD) calculations.     

3-氨基吲唑、炔醛和NIS串联环化反应合成碘化嘧啶并[1,2-b]-吲唑

本文开发了一种在无需外加添加剂的条件下合成碘代嘧啶并[1,2-b]-吲唑类化合物的方法。经研究发现,3-氨基吲唑、炔醛和碘代丁二酰亚胺在二氯甲烷中室温条件下发生直接串联环化反应,以中等至良好的产率得到碘代嘧啶并[1,2-b]-吲唑类化合物。该反应有较好的底物适应性,并具有绿色环境友好和操作简便等优点。     

NiWS/γ-Al2O3催化剂上吲哚加氢脱氮反应:H2S和喹啉的影响

在连续固定床微反装置上考察了吲哚（IND）和1,2-二氢吲哚（HIN）在NiWS/γ-Al₂O₃催化剂上加氢脱氮（HDN）的反应以及 H₂S和喹啉（Q）对其加氢脱氮反应的影响。结果表明,碱性含氮化合物HIN较吲哚对其自身的加氢脱氮反应抑制作用更为明显。H₂S能够促进HIN的C（sp³）－N断裂,但抑制了邻乙基苯胺（OEA）的 C（sp²）－N断裂;同时吲哚加氢反应途径也受到了抑制。喹啉的添加严重降低了吲哚加氢脱氮反应的转化率和脱氮率;喹啉对吲哚加氢反应和C－N键断裂反应均产生明显的抑制作用。喹啉的抑制作用主要源于喹啉及其中间产物1,2,3,4-四氢喹啉（THQ1）和5,6,7,8 -四氢喹啉（THQ5）与吲哚及其中间产物的竞争吸附。     

Spektrofluorometrische bestimmung von hydrazinen und deren anwendung zur quantitativen bestimmung von benzylhydrazin in biologischen proben

A spectrofluorometric determination of strong reducing substances such as hydrazine and alkylhydrazines is described. It is based on the reduction of 1,2-naphthoquinone-4-sulfonic acid to the fluorescent 1,2-dihydroxynaphthalene-4-sulfonic acid. The assay of microgram quantities of hydrazines in blood plasma and of benzylhydrazine in animal organs and urine is reported.     

Chromophore Systeme, 2. Konformation und Lichtabsorption von (2-Alkoxyvinyl)ethandionen

Chromophoric Systems, 2. – Conformation and Absorption of Light in (2-Alkoxyvinyl)ethanediones The unusual color properties of yellow 1,2-bis(4,5-dihydrofuran-3-yl)ethane-1,2-dione ( 1 ) and colorless 1,2-bis(5,6-dihydro-4H-pyran-3-yl)ethane-1,2-dione ( 2 ) in the solid state and in solution are investigated by crystal structure analysis, UV-Vis, PE, and ¹³C-NMR spectroscopy as well as by reparameterized force-field calculations. Dione 1 takes an antiperiplaner CO/CO conformation of its chromophore in the solid state whereas dione 2 is twisted in this respect by 102°. In solution both chromophores are not planar, but 1 is less distorted (ca. 142°) than dione 2 (ca. 126°). The calculated rotational barrier for CO/CO twisting amounts to 0.9 kcal mol⁻¹ for 1 and to 2.2 kcal mol⁻¹ for 2 .     

Electrochemical study of 1,2-Naphthoquinone-4-sulphonate and 1,2-Naphthoquinone semicarbazone

Summary A study of the electrochemical characteristics of 1,2-naphthoquinone-4-sulphonate, sodium salt, and of the semicarbazone of 1,2-naphthoquinone (Naftazone) was carried out using d.c., a.c. and d.p. polarography and cyclic voltammetry. Changes in the waves as a function of concentration and pH indicate evidence of adsorption phenomena at the potential of the reduction wave. These techniques also indicate the formation of a mercury derivative in the case of Naftazone. The quantitative determination of these two compounds is possible by polarography. Limits of detection are 5×10^–6 and 5×10^–8 M, respectively.

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Elektrochemische Untersuchung von 1,2-Naphthochinon-4-sulfonat und 1,2-Naphthochinon-semicarbazon

Zusammenfassung Die elektrochemischen Eigenschaften von 1,2-Naphthochinon-4-sulfonat und -semicarbazon (Naftazon) wurden mit Hilfe der Gleichstrom-, Wechselstrom und Differentialpuls-Polarographie sowie der cyclischen Voltammetrie untersucht. Veränderungen an den Stufen in Abhängigkeit von Konzentration und pH-Wert deuten auf Adsorptionsvorgänge beim Potential der Reduktionsstufe hin. Im Falle von Naftazon wurde die Bildung eines Quecksilberderivats nachgewiesen. Beide Substanzen können polarographisch mit Nachweisgrenzen von 5×10^–6 bzw. 5 × 10^–8 M bestimmt werden.