Functionalization of polyethylene/silane copolymers in posttreatment reactions

7‐Octenyldimethylphenylsilane was copolymerized with ethylene via Et(Ind)₂ZrCl₂ methylaluminoxane catalyst system without loss of catalyst activity or decrease in molar mass. The comonomer contents in the polymer samples were at a level of 0.15–1.0 mol % and the reactive phenylsilane groups were posttreated to different alcoxy‐ and halosilane groups, for example, Si? F, Si? Cl, Si? OCH₃, and Si? OCH₂CH₃. The posttreatment reactions had no major effect on the molar masses or on the thermal properties (measured with differential scanning calorimetry) of the copolymers. The reaction pathways were nearly independent of the comonomer contents and the reactions reached 70–100% conversions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1461–1467, 2004     

Thermal properties of poly(styrene) containing brominated aryl phosphate additives

General purpose poly(styrene) is a large volume commodity polymer widely used in a range of applications. For many of these the presence of an additive to impart some flammability resistance is required. Most commonly, brominated aromatics are used for this purpose. As the polymer undergoes combustion these compounds decompose to generate bromine atoms and/or hydrogen bromide which escape to the gas phase and trap flame propagating radicals. While these species are effective in inhibiting flame propagation they present the opportunity for loss of halogen to the atmosphere. For this reason, the use of these compounds is being limited in some parts of the world. Phosphorus compounds, on the other had, impart a flame retarding influence by promoting char formation at the surface of the burning polymer. This prevents heat feedback to the polymer and consequent pyrolysis to generate fuel fragments. The combination of both bromine and phosphorus present in a single compound might generate a superior flame-retarding additive in that both modes of retardancy might be promoted simultaneously. Should this be the case smaller amounts of additive might be necessary to achieve a satisfactory level of flame retardancy. A series of such additives, brominated aryl phosphates, has been synthesized and fully characterized spectroscopically. Blends of these additives, at various levels, with poly(styrene) have been examined by DSC, TG and in the UL-94 flame test. The flammability of the polymer is dramatically diminished by the presence of the additive.     

新型卤代羟基三苯醚的合成与抑菌活性研究

设计合成了对(间、邻)苯二酚二(4-氯-2-羟基苯基)醚(4a～4c)及对(间、邻)苯二酚二(4-氯-5-溴-2-羟基苯基)醚(5a～5c)共6个卤代羟基三苯醚类化合物,其结构均经1H NMR,IR,MS和元素分析证实,并且对其抑菌活性进行了初步测试.结果表明:此类化合物大多在低浓度下对大肠杆菌、金黄色葡萄球菌、白色念珠菌、白色葡萄球菌、变形杆菌、卡他双球菌、青枯假单胞菌等具有良好的抗菌活性.     

卤代化合物的光化学反应研究进展

介绍近年来卤代化合物在光照射下的偶联反应、醇解反应、消去反应、开环反 应，尤其是卤代杂环化合物的光化学反应，得到了许多用热反应或催化反应无法替 代的具有生物(理)活性的中间体．     

Trace analysis of volatile polar organics by direct aqueous injection gas chromatography

Summary Procedures for the quantitative analysis of industrial effluents which involve concentration by solvent extraction or the purge-and-trap method are time-consuming, labor-intensive, and prone to error. Direct aqueous injection gas chromatography using an electron-capture detector for the analysis of volatile halocarbons at the ppb level is in routine use in many laboratories. We now discuss the development of a similar protocol for the analysis of volatile polar organics such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and tretrahydrofuran using a flame-ionization detector.     

吹扫-捕集气相色谱法测定水中挥发性卤代烃

研究建立了吹扫 捕集法富集样品 ,利用HP 1大口径厚液膜通用型熔融石英毛细管柱 (30m× 0 .5 3mm×2 .6 5 μm) ,ECD检测器 ,测定水中 10种挥发性卤代烃的方法 ,确定了最佳吹扫 捕集条件 .结果表明 :水样体积为 5mL时 ,标准偏差在 0 .0 2～ 0 .0 7μg L之间 ,变异系数在 1.0 9%～ 3.2 8%之间 ,加标回收率为 94.0 %～ 10 7%之间 ,10种物质的检出限在 0 .0 7～ 0 .19μg L之间     

On the long‐range relativistic effects in the 15N NMR chemical shifts of halogenated azines

Long‐range β‐ and γ‐relativistic effects of halogens in ¹⁵N NMR chemical shifts of 20 halogenated azines (pyridines, pyrimidines, pyrazines, and 1,3,5‐triazines) are shown to be unessential for fluoro‐, chloro‐, and bromo‐derivatives (1–2 ppm in average). However, for iodocontaining compounds, β‐ and γ‐relativistic effects are important contributors to the accuracy of the ¹⁵N calculation. Taking into account long‐range relativistic effects slightly improves the agreement of calculation with experiment. Thus, mean average errors (MAE) of ¹⁵N NMR chemical shifts of the title compounds calculated at the non‐relativistic and full 4‐component relativistic levels in gas phase are accordingly 7.8 and 5.5 ppm for the range of about 150 ppm. Taking into account solvent effects within the polarizable continuum model scheme marginally improves agreement of computational results with experiment decreasing MAEs from 7.8 to 7.4 ppm and from 5.5 to 5.3 ppm at the non‐relativistic and relativistic levels, respectively. The best result (MAE: 5.3 ppm) is achieved at the 4‐component relativistic level using Keal and Tozer's KT3 functional used in combination with Dyall's relativistic basis set dyall.av3z with taking into account solvent effects within the polarizable continuum solvation model. The long‐range relativistic effects play a major role (of up to dozen of parts per million) in ¹⁵N NMR chemical shifts of halogenated nitrogen‐containing heterocycles, which is especially crucial for iodine derivatives. This effect should apparently be taken into account for practical purposes.     

N‐bromo‐hydantoin grafted polystyrene beads: Synthesis and nano‐micro beads characteristics for achieving controlled release of active oxidative bromine and extended microbial inactivation efficiency

N‐bromo‐hydantoin and N‐bromo‐5,5′‐dimethylhydantoin conjugated polystyrene beads were synthesized from chloromethyl polystyrene beads which differ in their particles size, crosslinking, nano‐micro porosity, and tunnels size on the surface, in order to study the effect of these parameters on oxidative halogen release and resultant activity, for water purification applications. The synthesized beads were characterized using elemental analysis, FT‐IR, solid state ¹³C‐NMR, and scanning electron microscope (SEM). The conjugation yield and kinetics in different solvents and bromine loading capacity were studied. The N‐bromoamine polystyrene beads were tested for water decontamination according to NSF 231 protocol. The release of active bromine was analyzed by spectrophotometer using a DPD‐1 kit and also studied the antimicrobial activity against Escherichia coli and MS2 phages. Bead's nano‐micro characteristics were found critical for oxidative halogen release control: rate stabilization and modulation, extension and also influences antimicrobial activity. The synthesized beads exhibited extended and stable release of bromine, 6 and 4 log reduction for E. coli and MS2, respectively for 250 L of passing contaminated water. Thus, N‐halamine hydantoins conjugated polystyrenes, chemically or kinetically release modified should have applications as disinfectants in water purification systems as well as medical field. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 596–610     

Reactivity of Various α-Halo Ketones in One-Pot Synthesis of γ-Iminolactones

The highly reactive 1:1 intermediate generated in the reaction of tert-butyl isocyanide and dialkyl acetylenedicarboxylate is trapped by α-halo ketones to produce halogenated iminolactones as the sole product in good yields.     

Cooperative Effect of Noncovalent Interactions on Tetrel Bonding in Halogenated Silanes

Tetrel bond, a weak noncovalent interaction between the σ-hole of a Group IV element (silicon in our case) and the cloud of an electronegative element (oxygen in our case) is the focus of this work. The percentage strengthening of tetrel bond has been investigated by optimizing 16 binary complexes of halogenated silane and water of general formula SiX_nH_4−n−H₂O and 16 ternary complexes, of general formula NaX−SiX_nH_4−n−H₂O, where X=F, Cl, Br and I and n=1, 2, 3 and 4 at various levels of theory defined within the formalism of density functional theory (DFT). With the addition of NaX, tetrel bond between Si and O in SiX_nH_4−n−H₂O gets strengthened up to 49 %, owing to cooperativity effect exerted by hydrogen bonding between X and H in the ternary complex NaX−SiX_nH_4−n−H₂O. In the series of complexes studied here, overall stabilization due to cooperativity lies between 10 kJ/mol to 170 kJ/mol. This large extent of reinforcement due to cooperativity has never been showcased before. The exceptional stabilization and reinforcement owe its genesis to the transformation of the ternary complex into a cluster orchestrated by the H-bonding in most of the cases and covalent bonding in few of the cases.