Gas chromatographic determination of 1,4-dioxane at low parts-per-million levels in glycols

1,4-Dioxane is a flammable liquid and tends to form explosive peroxides. Its formation in glycols (low parts-per-million levels), which are used as dehumidifying agents in refineries, may take place by condensation. 1,4-Dioxane thus formed gets distilled over with benzene in the refinery process. Therefore, it is necessary to identify and determine the levels of 1,4-dioxane in glycols as well as benzene. Gas chromatography (GC) is probably the best technique for this purpose. GC analysis may be carried out using a flame ionization detector. Results show that 1,4-dioxane can be comfortably determined down to 2 ppm in glycols and benzene.     

一种新型的用于质子交换膜燃料电池的磺化聚醚醚酮酮

以发烟硫酸和4,4-二(4-氟苯甲酰基)苯[1,4-bi(4-fluorobenzoyl)benzene]为原料,通过磺化反应,制得磺化二氟三苯二酮[1,4-bi(3-sodiumsulfonate-4-fluorobenzoyl)benzene].利用亲核缩聚反应,调整磺化单体和非磺化单体的比例,与酚酞进行聚合,制取了具有不同磺化度的聚醚醚酮酮,并对聚合物的结构进行了表征.结果表明,此系列磺化聚醚醚酮酮的膜制品具有良好的离子交换特性,可望应用于燃料电池膜.     

(Hetero) Arylene Polymers Having Polystyrene Chains as Branches

Summary : Four monomers; 1,4-bis(1-naphthyl) benzene ( 5 and 7 ) and 1,4-bis(2- thienyl)benzene ( 6 and 8 ) containing one or two polystyrene short chains substituted in 2 or 2, 5 positions of central phenylene ring were synthesized by Suzuki coupling reaction of two polystyrene based macromonomers ( 3 and 4 ) with 1-naphthalene- and 2-thiophene boronic acid, respectively. By chemical oxidative polymerization using FeCl₃ as oxidant, copolymers containing alternating phenylene and binaphthyl ( 9 , 11 ) or phenylene and bithienyl groups ( 10 , 12 ) and polystyrene as side chains have obtained. The exact control of polystyrene branch length was performed by atom transfer radical polymerization of styrene using as initiators 1,4 dibromo-2-(bromomethyl)benzene ( 1 ) and 1,4-dibromo-2,5 di(bromomethyl)benzene ( 2 ). Polymers were characterized by FT-IR, ¹H-NMR, UV and fluorescence spectroscopy and thermal methods.     

苯醌-DNA加合物的毛细管电泳方法研究

采用毛细管电泳相互作用分析法建立了一种直接评价污染物毒性的新方法。分别将毛细管区带电泳、胶柬电动力色谱与配体分离法结合,对苯醌和小牛胸腺DNA混合温育后的体系进行相互作用研究。研究发现,苯醌对小牛胸腺DNA能产生相互作用并形成DNA加合物,获得了苯醌对小牛胸腺DNA有损伤作用的判断。由于苯醌是苯在体内的代谢终产物,因此认为苯醌对DNA的损伤是苯致癌的途径之一。     

The development of corannulene-based blue emitters

Novel blue emitters were synthesized based on the fullerene fragment corannulene. 1,2- bis(corannulenylethynyl)benzene and 1,4-bis(corannulenylethynyl)benzene were designed, synthesized, and shown to exhibit significant red shifts in their absorption spectra as compared to that of the parent corannulene. Photoluminescence studies show both 1,2- bis(corannulenylethynyl)benzene and 1,4- bis(corannulenylethynyl)benzene gives enhanced blue luminescence compared to the parent corannulene structure. 1,4-bis(corannulenylethynyl)benzene was observed to give intense blue luminescence when excited at 400 nm. DFT and TD-DFT calculations were performed and shown to be consistent with the observed experimental results.     

TBP-TTA-C6H6三元体系活度系数的研究

如何计算与测量多组元体系的活度系数,是一个重要问题。我们的工作是选取了磷酸三丁酯(TBP)与硫国酰基三氟丙酮(TTA)溶于苯的体系,进行了实验测量与理论计算,理论与实验取得了基本一致的结果。     

Convenient Preparation of 1,4-Dibenzylbenzene using Zinc Chloride in the Presence of Polar Solvents

1,4-Dibenzylbenzene was successfully synthesized by the Friedel-Crafts benzylation of benzene with 1,4-bis(chloromethyl)benzene using zinc chloride in the presence of polar solvents. In particular, zinc chloride dissolved in primary alcohols or ketones with a molar ratio of 1 was a highly effective catalytic system in the reaction.     

Using isopropanol as solvent in favor of <Emphasis Type="Italic">p</Emphasis>-xylene electrochemical oxidation

It was found that isopropanol as solvent was propitious to the p-xylene electrochemical oxidation, then obtained the 1,4-bis(methoxymethyl) benzene or 1-dimethoxymethyl-4-methyl benzene. When the isopropanol was added in 20 ml, the 1,4-bis(methoxymethyl) benzene or 1-dimethoxymethyl-4-methyl benzene of products was 36.09%. Compared to no isopropanol, the experimental result showed that the total yield of products above can be obviously increased. On the conditions of room temperature and constant current intensity, the reaction was carried out in a single-compartment cell by the use of a pair of graphite plane electrodes. The testing process was tracked by UV-vis spectrum. In succession, we adopted gas chromatography / mass spectrometry and gas oil octane number test to detect the final production. Based on the gas oil octane number test result, the production can be used as the gas oil additive.     

Synergic liquid/liquid extraction of lithium and sodium with 4-acyl-5-pyrazolones with bulky substituents and tri-n-octylphosphine oxide

The synergic liquid/liquid extraction of lithium and sodium with 4-acyl-5-pyrazolones having bulky substituents and tri-n-octylphosphine oxide (TOPO) is described. The maximum percentage extraction and the separation of lithium and sodium were improved by introducing bulky substituents. Quantitative extraction (? 99% ) of lithium could be achieved by adduct formation with TOPO, which enhanced the extraction much more than did triphenylphosphine oxide. The extraction decreased in the solvent order cyclohexane ? benzene ? chloroform, which is the general trend in synergic extractions.     

苯在Si(111)-7*7表面化学吸附的理论研究

采用两种大小不同的原子簇模型Si_(30)H_(28)和Si_(13)H_(16),分别用两层 ONIOM方法（对较大原子簇）和普通量子化学方法（对较小原子族）考察了苯分子 在Si(111)-7 * 7表面的化学吸附。对三种可能的吸附物种分别用DFT或HF方法进行 了计算。通过大小原子簇吸附物种的吸附能以及几何构型优化参数的比较发现,对 于稳定的吸附物种,较小的原子簇基本上可以代替较大的原子簇进行计算,而对于 不太稳定的吸附物种,就不得不考虑周边原子的影响。计算结果表明苯在Si(111)- 7 * 7表面的主要吸附种是双σ成键的1,4加成产物,不稳定的单吸附物种可能是 1,4加成物种的前驱态。     

Transformations of cyclohexa-1,4-diene under the action of biphenyl—alkali metal systems in THF. Synergistic acceleration by mixtures of lithium and sodium

In the interaction of cyclohexa-1,4-diene (1,4-CHD) with a mixture of biphenyl and metallic lithium or sodium in THF at 20 °C, three processes occur, viz., disproportionation of 1,4-CHD to form benzene and cyclohexene, dehydrogenation of 1,4-CHD to form benzene and molecular hydrogen, and dehydrogenation of 1,4-CHD to form benzene and lithium or sodium hydride. In the case of lithium on the use of an equimolar amount of biphenyl, the isomerization of 1,4-CHD to cyclohexa-1,3-diene is also observed. When the molar ratio Li(Na): Ph₂ increases from 1 : 1 to 2 : 1, i.e., when the reaction is carried out in the presence of an alkali metal solid phase, the overall conversion of 1,4-CHD into benzene and cyclohexene increases. The use of mixtures of lithium and sodium leads to acceleration of the processes of the formation of benzene and cyclohexene. The possible mechanism of the synergistic effect found is discussed.     

2,5-二叔丁基-1,4-二(对苯甲酸氧基)苯的合成与表征

4-氟苯腈和2,5-二叔丁基对苯二酚亲核取代反应合成2,5-二叔丁基-1,4-二（对苯腈氧基）苯（产率87.00%,白色晶体,mp280℃）,然后将二腈在碱性条件下水解,合成了1种分子中同时含有2个醚键和2个叔丁基的芳香族二酸--2,5-二叔丁基-1,4-二（对苯甲酸氧基）苯（产率72.78%,白色针状晶体,mp＞340℃）。产物经元素分析和IR、¹H NMR、¹³C NMR和MS波谱表征确证。     

Two-photon photochromism of diarylethene dimer derivatives.

Photochromic diarylethene dimer derivatives with large two-photon absorption (TPA) cross-sections have been designed and synthesized. The derivatives have a D-pi-D structure in which indole rings are used as donor units (D) and 1,4-bis(ethynyl)benzene or 1,4-bis(ethenyl)benzene as a pi-conjugated chain unit (pi). Compound 5 a, which has oxazole rings as one of the aryl groups, showed a TPA cross-section of 23 GM at 820 nm and exhibited efficient two-photon photochromic reactivity.     

Photo-Fries rearrangement: Rearrangement of benzoyloxy compounds

Photo-Fries migration of the benzoyl group in 1-benzoyloxy-5-methoxy naphthalene, 1,4-dibenzoyloxy-2-methyl naphthalene, 1,4-dibenzoyloxy naphthalene, 1,5-dibenzoyloxy naphthalene, 8-benzoyloxy quinoline, 1,2-dibenzoyloxy benzene, 1,3-dibenzoyloxy benzene, and 1,4-dibenzoyloxy benzene afforded the corresponding mono and di-C-benzoyl products.

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Photo-Fries-Umlagerung: Umlagerung von Benzoyloxy-Verbindungen

Zusammenfassung Die Photo-Fries-Wanderung der Benzoylgruppe in 1-Benzoyloxy-5-methoxynaphthalin, 1,4-Dibenzoyloxy-2-methylnaphthalin, 1,4-Dibenzoyloxy-naphthalin, 1,5-Dibenzoyloxynaphthalin, 8-Benzoyloxychinolin, 1,2-Dibenzoyloxybenzol, 1,3-Dibenzoyloxybenzol und 1,4-Dibenzoyloxybenzol ergab die entsprechenden Mono- und Di-C-Benzoyl-Produkte.

     

Influence of samarium on the electrocatalytic activity of platinum electrodes for the hydrogenation of benzene

The hydrogenation of benzene on platinum electrodes in 0.5 M sulfuric acid as supporting electrolyte has been studied in the presence and the absence of samarium in solution. The hydrogenation overpotential of preadsorbed benzene was diminished to 90 mV with samarium in the solution and the hydrogenation current was significatively increased. These results are interpreted in terms of a synergic effect of samarium on hydrogen adsorption and, consequently, on the electrocatalytic activity of the platinum electrode for the hydrogenation of benzene.     

Molecular "compasses" and "gyroscopes". I. Expedient synthesis and solid state dynamics of an open rotor with a bis(triarylmethyl) frame

We describe our efforts toward the preparation of materials built with molecules possessing topologies analogous to those of macroscopic compasses and gyroscopes. Samples of 1,4-bis(3,3,3-triphenylpropynyl)benzene (3) were prepared by a simple two-step procedure from triphenylmethyl chloride (1) and 1,4-diiodobenzene. The structure of compound 3 is such that the central phenylene can play the role of a gyroscope wheel while the two tritylpropynyl groups can act as an axle and shielding framework. Crystals of a benzene clathrate were characterized by single crystal X-ray diffraction and variable-temperature solid state NMR while their thermal stability was determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The rotational dynamics of the phenylene group in the benzene clathrate and in desolvated samples were characterized in terms of a two-fold flipping process. Solid state rotational barriers of ca. 12.8 and 14.6 kcal/mol were estimated for the benzene clathrate and desolvated samples, respectively.     

Perfluorinated cyclo-tetrakis(phenylene sulfides): synthesis and structure

Perfluoro-cyclo-tetrakis(1,4-phenylene sulfide) has been synthesized by the reaction of tetrafluorobenzene-1,4-dithiol with perfluoro-1,4-bis(phenylthio)benzene. The reaction of tetrafluorobenzene-1,4-dithiol with perfluoro-m-xylene gives a macrocycle with 1,3- and 1,4-arrangement of bridged sulfur atoms.     

Hydrogen‐bonded thermotropic liquid‐crystalline polyester–amides from bis(hydroxy alkamido)aranes: Synthesis and properties

Hydrogen‐bonded aromatic–aliphatic polyester–amides (PEAs) were prepared by solution/melt polycondensation of aromatic–aliphatic amidodiols 1,4‐bis(4‐hydroxybutyramide)benzene (BHBB), 1,4‐bis(5‐hydroxy pentamide)benzene, 1,4‐bis(6‐hydroxyhexamide)benzene, 1,4‐bis(4‐hydroxybutyramidexylene), 1,4‐bis(5‐hydroxypentamidexylene, 1,4‐bis(4‐hydroxybutyramide)benzene, and 1,4‐bis(6‐hydroxyhexamidexylene) with terephthaloyl chloride/dimethyl terephthalate. Aromatic–aliphatic amido diols were prepared by the aminolysis of γ‐butyrolactone, δ‐valerolactone, and ?‐caprolactone with aromatic diamines such as paraphenylene diamine and paraxylene diamine. The monomers and polymers were characterized by chemical analysis (hydroxyl value and elemental analysis), Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR. The thermal‐ and phase‐transition behaviors of the polymers were investigated by differential scanning calorimetry in combination with hot‐stage optical microscopy. Crystallinity of polymers was examined with wide‐angle X‐ray diffraction. The polymers exhibited liquid crystallinity with layered structures formed by self‐organization of the hetero intermolecular hydrogen‐bonded networks indicating smectic phases except for PEAs prepared from BHBB. The hydrogen atom of the phenyl‐substituent group forces the neighboring carbonyl groups out of plane of the rings preventing formation of layered structures in the case of BHBB. The PEAs retained intermolecular hydrogen bonding even in the mesomorphic state, and variations in the hydrogen‐bonded lamellae/micelles might be responsible for the variations from one smectic to another texture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 335–346, 2003     

1,4-二(2-苯并(口恶)唑基)苯及其衍生物紫外光谱和荧光光谱的溶剂效应

测定了1,4-二(2-苯并(口恶)唑基)本及其5,5′-二取代衍生物共八种化合物在十五种溶剂中的紫外吸收光谱及1,4-二(2-苯并(口恶)唑基)苯在九种溶剂中的荧光发射光谱。用二元回归分析和两类溶剂参数的双参数方程处理数据,得到了较一元回归和单参数方程更好的相关关系。     

Synthesis,electrochemistry and IR spectroelectrochemistry of bisferrocenyl bridged benzene derivates

Two novel biferrocenylcarboxylate benzene derivatives, namely, 1,4-bis(2-Ferrocenecarboxylate) benzene (Fc₂B) and 1,4-bis(2-Ferrocenecarboxylate)-2′-methylbenzene (Fc₂M), have been synthesized. The as-prepared complexes have been confirmed by IR, ¹H NMR and MS. The electron transfer mechanisms of the two compounds and the other three bisferrocenyl bridged benzene complexes, 1,4-disferrocenyl benzene (Fc₂P), 1,4-bis(2-ferrocenylvinyl) benzene (Fc₂E), and 1,4-bis(2-ferrocenylacetyleneyl) benzene (Fc₂Q), have been studied by cyclic voltammetry (CV), in situ difference FT-IR (SNFTIR), and rapid-scan time-resolved FT-IR spectroelectrochemistry (RS-TRS FT-IR). The CV results suggest that the redox formal potentials of the five bridged complexes are depended on their bridged groups and abilities of withdrawing electron. IR absorption peaks arisen from intermediate appearance and disappearance in the oxidation and reduction process of Fc₂B, Fc₂E, Fc₂P and Fc₂Q were clearly observed by the in situ rapid-scan or SNFTIR spectroelectrochemistry. The results indicated the redox process of the four bisferrocenyl bridged benzene complexes involved two consecutive one-electron steps. Although the intermediate peak of Fc₂M was not observed by in situ FT-IR spectroelectrochemistry, we still thought the redox process of Fc₂M could involve two consecutive one-electron steps.