Polymerization of – Phenylmaleimide Initiated by 9-Borabicyclo[3.3.1]nonane

N-Phenylmaleimide (N-PMI) was polymerized by 9-borabicyclo[3.3.1] nonane (9-BBN) in tetrahydrofuran under argon at 0°C. The molecular weight distributions of the resulting polymers were around 1·1. The rate of poly-merization was proportional to [9-BBN]^1·18 and [N-PMI]^1·24. Hydroquinone had little effect on the rate of polymerization and on the molecular weight of the polymers obtained. Triethylamine completely inhibited the polymerization, and aniline with a relatively small pK_a value and zinc iodide effectively retarded the polymerization. The polymerization did not proceed either in polar dimethylformamide or in non-polar toluene. In polymerizations at temperatures higher than 60°C the conversions decreased. On the basis of the results, a non-radical mechanism was proposed for this polymerization. © of SCI.     

Polymerization of α,β-unsaturated carbonyl monomers initiated by 9-borabicyclo [3.3.1] nonane

9-Borabicyclo[3.3.1]nonane (9-BBN) initiated the polymerization of α,β-unsaturated carbonyl monomers such as ethyl acrylate (EA) without an oxidant at low temperatures (to −90°C) under argon. Hydroquinone and 2,6-di-tert-butyl-p-cresol had little effect on the polymerization, indicating that the propagating chain end is not a free radical. The rate of polymerization was found to be proportional to [9-BBN]^1.0 and [EA]^1.5. Electron spin resonance measurements using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap showed the absence of any radical species under polymerization conditions. No copolymerization of EA with styrene occurred. On the basis of the results obtained, this polymerization was assumed to proceed via a non-radical mechanism.     

8-苄基-2,8-二氮杂双环[4.3.0]壬烷的合成

采用氢化铝锂还原8-苄基-7,9-二氧代-2,8-二氮杂双环[4.3.0]壬烷（C₁₄H₁₆N₂O₂）,得目标产物8-苄基-2,8-二氮杂双环[4.3.0]壬烷（C₁₄H₂₀N₂）,确定了最佳工艺条件。结果表明,以四氢呋喃作溶剂,n(C₁₄H₁₆N₂O₂):n(LiAlH₄)=1:3.2和反应时间为16 h时,产物收率可达93.73%;产物经元素分析、红外光谱分析确认。     

Stereoselective reduction of (±)-bicyclo[3.3.1]nonane-2,6-dione by microorganisms

The biotransformation of (±)-bicyclo[3.3.1]nonane-2,6-dione by Aspergillus niger and Glomerella cingulata was investigated. The diketone was reduced to the ketoalcohol 2-endo-hydroxy-bicyclo[3.3.1]nonane-6-one and the diol endo,endo-bicyclo[3.3.1]nonane-2,6-diol respectively. Endo,endo-bicyclo[3.3.1]nonane-2,6-diol and ketoalcohols produced by G. cingulata had high optical purity, on the other hand, reduction by A. niger yielded optically active (-)-(1R, 2S, 5R, 6S)-bicyclo[3.3.1]nonane-2,6-diol(99·9% e.e.). © 1998 SCI     

Enhanced high-temperature resistance and magnetic property of SiFeC nanocomposites containing a small amount of boron

In this paper, the boron-modified polyferrocenylcarbosilanes (namely HBPFCS-Bs) with hyperbranched structure, as single-source-precursors, were successfully prepared by using 9-borabicyclo [3, 3, 1] nonane (9-BBN) and polyferrocenylcarbosilanes (HBPFCSs) as starting materials. The obtained HBPFCS-Bs were characterized using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC), providing that the boron element can be introduced into the HBPFCS chains by the hydroboration (B-H/C = C) reaction. Then, the structural evolution of HBPFCS-Bs and the boron-containing SiFeC ceramics at different temperatures (1100–1500°C) was further investigated by thermogravimetric analysis, X-ray diffraction, energy dispersive spectroscopy, scanning electron microscope, and transmission electron microscopy. The results show that the incorporation of a small amount of boron (1 wt%) into precursors significantly improves the properties of the final ceramics, including the significant increase of the ceramic yield, enhanced high-temperature resistance, as well as the higher ceramic densification. Finally, the saturation magnetization of the HBPFCS-Bs-derived ceramics was also enhanced by the introduction of boron.     

间歇式乳液聚合法制备超支化聚丙烯酸丁酯

以丙烯酸丁酯为单体,二乙烯基苯为支化剂,十二硫醇为链转移剂,通过间歇式乳液聚合法成功制备了一系列高转化率的聚丙烯酸丁酯超支化聚合物。通过核磁共振对其结构进行了表征,同时还对聚合物乳液粒径及其分布,超支化聚合物的溶解性、支化度、相对分子质量及相对分子质量分布进行了研究。结果表明:超支化聚合物分子结构中含有丙烯酸丁酯、二乙烯基苯和十二硫醇;聚合物乳液粒径较小,粒径分布较窄;超支化聚合物在有机溶剂中具有良好的溶解性;随着支化剂用量的增加,聚合物支化度增加,相对分子质量降低,相对分子质量分布变窄;随着链转移剂用量的增加,聚合物支化度增加,相对分子质量分布变窄。     

Controlled radical double ring‐opening polymerization of 2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane

Controlled radical double ring‐opening polymerization of 2‐methylene‐1,4,6‐trioxaspiro[4,4]nonane (MTN) has been achieved with tert‐butyl perbenzoate (TBPB) as initiator in the presence of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy free radical (TEMPO) at 125 °C. The molecular weight polydispersity of the polymers is obviously lower than that of polymers obtained by conventional procedures. As the [TEMPO]/[TBPB] molar ratio increased, the polydispersity decreased and a polydisperty as low as 1.2 was obtained at high TEMPO concentration. With the conversion of the monomer increasing, the molecular weight of the polymers turned higher and a linear relationship between the M_w and the monomer conversion was observed. The monomer conversion, however, did not exceed 30 %. © 2000 Society of Chemical Industry     

Butyl Acrylate/Vinyl Acetate Emulsion‐Based Pressure‐Sensitive Adhesives: Empirical Modelling of Final Properties

The influence of the amounts of acrylic acid, chain transfer agent and anionic stabilizer on polymer microstructural properties and final adhesive performance of BA/VAc emulsion‐based PSAs on stainless‐steel and high‐density polyethylene substrates was investigated using a Box‐Behnken experimental design for 15 runs. The resulting data were empirically modelled. For each final adhesive property (i.e., loop tack, shear and peel strength), different models were found to fit the data. Similar models for loop tack and peel strength were found to be adequate for different PSA thicknesses on the same substrate. AA and SDS had significant effects on loop tack as did the AA‐SDS and CTA‐SDS two‐factor interactions. Quadratic peel strength models were found to adequately describe the data for SS substrate cases with a noticeable absence of any interaction parameters. The shear strength models were similar regardless of the substrate or thickness of the adhesive (e.g. in all models, AA and CTA, as well as their second‐order interactions, were the significant factors).     

Empirical Modeling of Butyl Acrylate/Vinyl Acetate/Acrylic Acid Emulsion‐Based Pressure‐Sensitive Adhesives

Summary: Butyl acrylate/vinyl acetate/acrylic acid (BA/VAc/AA) emulsion latexes were produced in a semi‐batch mode. The objective was to generate polymers with properties favoring their application as pressure‐sensitive adhesives. The influence of the individual monomer concentrations on final properties such as glass transition temperature (T_g), peel strength, shear strength and tack was investigated. To obtain the maximum amount of information in a reasonable number of runs, a constrained three‐component mixture design was used to define the experimental conditions. Latexes were coated onto a polyethylene terephthalate carrier and dried. Different empirical models (e.g. linear, quadratic and cubic mixture models) governing the individual properties (i.e. T_g, peel adhesion, shear resistance and tack) were developed and evaluated. In the given experimental region, no single model was found to fit all of the responses (i.e. the final properties). However, in all models the most significant factor affecting the final properties was the AA concentration, followed by the VAc concentration.

Shear strength contour lines over the investigated region.     

电感耦合等离子体质谱法(ICP-MS)测定莫西沙星侧链中钯金属残留

建立了电感耦合等离子体质谱(ICP-MS)测定莫西沙星侧链-(S,S)-2,8-二氮杂双环[4,3,0]壬烷中钯金属残留的方法。样品经强酸高温消解后,采用ICP-MS测定。钯在2.0～20μg/L范围内线性关系良好(r>0.999),在4、10和16μg/kg添加浓度下,方法回收率为87.3～98.5%,RSD为1.86～6.39%。方法检出限和定量限分别为2μg/kg、40μg/kg。该法快速、准确、灵敏高,可以用于莫西沙星侧链中钯元素测定。     

Simple introduction of anion trapping site to polymer electrolytes through dehydrocoupling or hydroboration reaction using 9-borabicyclo[3.3.1]nonane

Organoboron-based anion trapping polymer electrolytes were synthesized through hydroboration or dehydrocoupling reaction between poly(propylene oxide) (PPO) oligomer (M_n = 400, 1200, 2000 and 4000) and 9-borabicyclo[3.3.1]nonane (9-BBN). Obtained oligomers were added various lithium salts (LiN(CF₃SO₂)₂, LiSO₃CF₃, LiCO₂CF₃ or LiBr) to analyze the ionic conductivity and lithium ion transference number (tLi⁺). The ionic conductivity of the oligomer in the presence of LiN(CF₃SO₂)₂ showed higher ionic conductivity than other systems, however, the tLi⁺ was less than 0.3. When LiSO₃CF₃ or LiCO₂CF₃, was added high tLi⁺ over 0.6 was obtained. Such difference in tLi⁺ can be explained by HSAB principle. Since boron is a hard acid, soft (CF₃SO₂)₂N⁻ anion can not be trapped effectively. High ionic conductivity of 1.3 × 10⁻⁶ S cm⁻¹ and high tLi⁺ of 0.73 was obtained when PPO chain length was 2000. These values of facilely prepared polymer electrolytes are comparable to those of the PPOs having covalently bonded salt moieties on the chain ends.     

Ring-opening polymerization of 1 -ethylbicyclo[2.2.1] hept-2-ene

1-Ethylbicyclo[2.2.1]hept-2-ene has been polymerized using a range of metathesis catalysts and the structure of the polymers determined by ¹³C n.m.r. spectroscopy. For a given catalyst the cis double bond content was lower and the head-tail bias greater than for polymers of the 1-methyl analogue. This is interpreted in terms of enhanced steric and polar effects brought about by the ethyl substituent.     

Nature of Linear Spectral Properties and Fast Electronic Relaxations in Green Fluorescent Pyrrolo[3,4-c]Pyridine Derivative

The electronic nature of 4-hydroxy-1H-pyrrolo[3,4-c]pyridine-1,3,6(2H,5H)-trione (HPPT) was comprehensively investigated in liquid media at room temperature using steady-state and time-resolved femtosecond transient absorption spectroscopic techniques. The analysis of the linear photophysical and photochemical parameters of HPPT, including steady-state absorption, fluorescence and excitation anisotropy spectra, along with the lifetimes of fluorescence emission and photodecomposition quantum yields, revealed the nature of its large Stokes shift, specific changes in the permanent dipole moments under electronic excitation, weak dipole transitions with partially anisotropic character, and high photostability. Transient absorption spectra of HPPT were obtained with femtosecond resolution and no characteristic solvate relaxation processes in protic (methanol) solvent were revealed. Efficient light amplification (gain) was observed in the fluorescence spectral range of HPPT, but no super-luminescence and lasing phenomena were detected. The electronic structure of HPPT was also analyzed with quantum-chemical calculations using a DFT/B3LYP method and good agreement with experimental data was shown. The development and investigation of new pyrrolo[3,4-c]pyridine derivatives are important due to their promising fluorescent properties and potential for use in physiological applications.     

新型杯[4]芳烃醚的合成及其酯交换反应研究

以正丁醛杯[4]芳烃母体化合物1与溴乙酸乙酯反应,得到杯[4]芳烃醚2,再与9-蒽甲醇进行酯交换反应,得到目标化合物3。对化合物2和目标化合物3的结构进行了熔点、红外光谱、核磁共振谱的表征。     

3-[(2,3-二氢噻吩并[3,4-b]-1,4-二噁英-2-基)甲氧基]-丙酸的合成工艺改进

报道了一种合成标题化合物的新工艺。以噻吩并[3,4-b]-1,4-二噁英-2-甲醇为起始原料,与丙烯酸叔丁酯发生迈克尔加成反应得到中间体化合物3-[(2,3-二氢噻吩并[3,4-b]-1,4-二噁英-2-基)甲氧基]丙酸叔丁酯。将得到的中间体在碱性条件下进行水解反应,然后采用盐酸进行酸化,最终经过干燥、减压浓缩、洗脱等后处理得到合格的标题化合物,总产率为71.2%,标题化合物及中间体经¹HNMR确认结构。路线操作简便、反应条件温和、产品质量可控,具有一定的工业应用意义。     

Selective online solid-phase extraction of copper using p-morpholino-methylcalix[4]arene appended silica-based column

ABSTRACT

This study deals with investigation of selectivity of p-morpholino-methylcalix[4]arene appended silica from a group of metal ions having similar charge and radii. The values of distribution ratio revealed that modified silica possess higher selectivity for Cu²⁺. In addition, relative selectivity coefficients of modified silica were found to be 24.1, 13.8, 8.6 and 4.01 for Cu²⁺/Ni²⁺, Cu²⁺/Co²⁺, Cu²⁺/Cd²⁺, Cu²⁺/Pb²⁺, respectively. The maximum adsorption capacity was 1.5 mmolg^?1. The reusability data suggested no any loss of adsorption capacity of this material up to 10 cycles. The developed material was also applied for determination of copper in lake water samples with satisfactory results.     

Synthesis of hypergrafted poly[4-(N,N-diphenylamino)methylstyrene] through tandem anionic-radical polymerization of radical-inimer

In this paper, we present a tandem anionic-radical approach for synthesizing hypergrafted polymers. We prepared 4-(N,N-diphenylamino)methylstyrene (DPAMS) as a new radical-based inimer. Linear PDPAMS was prepared through anionic polymerization. Hypergrafted PDPAMS was synthesized through the self-condensing vinyl polymerization of DPAMS with linear PDPAMS. The linear backbone of PDPAMS, which incorporated latent radical initiating sites, served as a ‘hyperlinker’ to link hyperbranched side chains. The molecular weights of hypergrafted polymers increased as the length of the linear backbone chain increased. The hypergrafted structure of the resulting polymer was confirmed using a conventional gel permeation chromatograph apparatus equipped with a multiangle light scattering detector, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. This strategy can be applied to synthesize other complex architectures based on hyperbranched polymers by changing the structure of a polymer backbone through anionic polymerization.     

Using a polymer‐supported azide ion in [2+3] cycloaddition reaction of azide ion with nitriles

The [2+3] cycloaddition between various nitriles and crosslinked poly(4‐vinylpyridine) supported azide ion proceeds smoothly in the presence of ammonium bromide or ammonium chloride in N,N‐dimethyl formamide, to give the corresponding 5‐substituted‐1H‐tetrazoles in good to high yields. Conventional heating was used to promote reaction. It was found that using nitriles with electron‐withdrawing groups result in bout higher yields and lower reaction times. The present procedure offers advantages, such as shorter reaction time, and simple workup. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A Morphological Study of Poly[Bis(Trifluoroethoxy)Phosphazene] Using Solid-State NMR: Introducing Domain Selective 1H and 19F Decoupled 13C MAS NMR

Using solid-state NMR methods the morphological behavior of poly[bis(trifluoroethoxy)phosphazene] was studied, employing four nuclei of interest – ¹H, ¹⁹F, ³¹P and ¹³C. Measurements on all four nuclei support that at ambient temperature the crystalline and amorphous phases coexist. Variable temperature studies showed that above T(1) = 90° only a single highly mobile phase exists, which is presumed to be the 2D mesophase. All four nuclei showed that when heat cycling the polymer, repeatedly above T(1), an increase in crystallinity occurs with each cycle. For the first time ¹³C MAS NMR spectra, using high power ¹⁹F and ¹H decoupling, were obtained, which exhibited the same behaviour domain. Filtered ¹³C{¹H,¹⁹F} MAS spectra containing signal from the crystalline domain using the discrimination induced by variable amplitude minipulses (DIVAM) sequence were measured. Heat treated and solvent cast material showed differences in these ¹³C spectra, that were consistent with a decrease in backbone conformations upon heating, suggesting an increase in the extended chain form corresponding to the γ form. Analogous sensitivity to variations in crystal phase composition has not been seen previously using ¹H, ¹⁹F and ³¹P methods, emphasizing the importance of ¹³C MAS methods to morphological studies of phosphazenes. This paper is dedicated to Professor Harry R. Allcock