Formation of five- and six-membered heterocyclic rings under radical cyclisation conditions

This review describes the formation of five- and six-membered heterocyclic rings in various organic molecules by radical cyclisation and covers mostly the literature published in 2005.     

Optimization of butyltin measurements for seawater,tissue, and marine sediment samples

Optimized techniques for measuring butyltins at the sub-part-per-trillion (ppb; 1:10¹²) level in seawater and at the part-per-billion (ppb; 1:10⁹) level in tissues and sediments are presented. Purge and trap/hydride derivatization followed by atomic absorption (AA) detection was optimized to give better sensitivity than was previously attained for seawater, yielding environmental detection limits of 0.08–0.2 ng dm^?3. Improvement in precision and reproducibility in measurement of butyltins in tissues and sediments was attained by adjustment of the concentration in an organic extract to minimize matrix effects and by use of internal standards. The tissues and sediments were homogenized and extracted with methylene chloride (CH₂Cl₂) after acidification. The butyltins in the organic layer were derivatized with hexylmagnesium bromide and analyzed by gas chromatography (GC) with a flame photometric detector (FPD). The absolute detection limits in tissues and sedimets were 0.1 ng for tributyltin (TBT), 0.12 ng for dibutyltin (DBT) and 0.29 ng for monobutyltin (MBT).     

Environmental aspects of tributyltin

The tributyltin species, the active ingredient in some antifouling paint formulations, is perhaps the most acutely toxic chemical to aquatic organisms ever deliberately introduced to water. It has been demonstrated to have an adverse effect on shellfish in France and England, and as a consequence the use of tributyltin-containing antifouling paints has been restricted in these countries. Other countries have banned the use of tributyltin-containing antifouling paints or are contemplating restrictions. This article reviews such environmental aspects of tributyltin as methods of analysis, toxicity, environmental occurrence, persistence and fate. Tributyltin concentrations in many locations may be high enough to cause chronic toxicity or harmful effects in some aquatic organisms, and in some locations the tributyltin concentrations may be high enough to be acutely toxic to some organisms. Biological degradation of tributyltin in water and sediment appears to be the most important factor limiting the persistence of tributyltin in aquatic environments. To some degree, then, the persistence of tributyltin in aquatic environments depends upon the nature of the ecosystem. Tributyltin exhibits low-to-medium persistence in water and moderate persistence in sediment. A summary is given of the regulatory status of tributyltin in some countries, and recommendations are made for further research.     

Macrocyclic polyamine-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith for capillary electrochromatography

1,4,10,13,16-Pentaazatricycloheneicosane-9,17-dione (macrocyclic polyamine)-modified polymer-based monolithic column for CEC was prepared by ring opening reaction of epoxide groups from poly(glycidyl methacrylate-co-ethylene dimethacrylate) (GMA-co-EDMA) monolith with macrocyclic polyamine. Conditions such as reaction time and concentration of macrocyclic polyamine for the modification reaction were optimized to generate substantial EOF and enough chromatographic interactions. Anodic EOF was observed in the pH range of 2.0-8.0 studied due to the protonation of macrcyclic polyamine at the surface of the monolith. Morphology of the monolithic column was examined by SEM and the incorporation of macrocyclic polyamine to the poly(GMA-co-EDMA) monolith was characterized by infrared (IR) spectra. Successful separation of inorganic anions, isomeric benzenediols, and benzoic acid derivatives on the monolithic column was achieved for CEC. In addition to hydrophobic interaction, hydrogen bonding and electrostatic interaction played a significant role in the separation process.     

铁系催化剂催化降冰片烯与甲基丙烯酸特丁酯共聚

研究了Fe(acac)3-Al(i-Bu)3(acac=乙酰丙酮)催化降冰片烯(NB)与甲基丙烯酸特丁酯(TBMA)共聚反应条件影响、第三组份影响及催化剂铁铝比影响.并用核磁共振、红外光谱方法研究了共聚物的组成,用凝胶渗透色谱分析了聚合物的分子量及分布.用扫描电镜研究了共聚物成膜性.     

THE SYNTHESIS OF NEW POLED CROSSLINKED POLYMETHACRYLATES AND THEIR SECOND ORDER NONLINEAR OPTICAL PROPERTIES

Films were prepared from mixtures of copolymers of 4-nitro-4'- [N- methylacryloyloxyethyl,N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) andcopolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophorecontent: 25 mol %). During thermal poling process the anhydride reacts with the epoxygroup and the resulting crosslinked network structure will stabilize the second harmonicgeneration in the poled film. The second harmonic generation of the poled film shows amaximum with the variation of composition, this is presumed to be due to the effects of theincreasing of concentration, orientation order as well as orientation stability of chromophoregroups during crosslinking.     

Photo‐polymerized lauryl methacrylate monolithic columns for CEC using lauroyl peroxide as initiator

Lauryl methacrylate (LMA)‐ester based monolithic columns photo‐polymerized using lauroyl peroxide (LPO) as initiator were prepared, and their morphological and CEC properties were studied. The composition of the polymerization mixture (i.e. ratios of monomers/porogenic solvents, 1,4‐butanediol/1‐propanol and LMA/crosslinker) was optimized. The morphological and chromatographic properties of LMA columns were evaluated by means of SEM pictures and van Deemter plots of PAHs, respectively. The polymerization mixture selected as optimal provided a fast separation of a mixture of PAHs with excellent efficiencies (minimum plate heights of 8.9–11.1 μm). Satisfactory column‐to‐column (RSD<4.5%) and batch‐to‐batch reproducibilities (RSD<6.3%) were achieved. The LMA columns photo‐polymerized with LPO were compared with those prepared with AIBN. Using PAHs, alkylbenzenes and basic compounds for testing, the columns obtained with LPO gave the best compromise between efficiency, resolution and analysis time.     

N-(P-羟甲基苯基)咔唑丙烯酸酯的合成和聚合

<正> 为了深入认识含咔唑基单体的光敏性与聚合性的关系,在本系列含咔唑基化合物的基础上,合成了两个新单体:N-(p-羟甲基苯基)咔唑丙烯酸酯和N-(P-羟甲基苯基)咔唑甲基丙烯酸酯,并研究了其聚合行为。 化合物Ⅰ、Ⅱ、Ⅲ和聚合物的合成,反应式如下:     

Determination of Tributyltin in Sea Water by Hydride Generation-Atomic Absorption Spectrometry

A hydride generation-atomic absorption spectrometry (HG-AAS) procedure is described for the analysis of tributyltin (TBT) in sea water. TBT is first converted to its volatile hydride form by reaction with sodium borohydride, followed by cryogenic trapping at ?196°C, and finally detection by atomic absorption spectrometry using an electrically heated quartz atomization cell. The linear range of calibration is 5-250 ng TBT (as tin). At the 5-ng level, the relative standard deviation (RSD) is 13%. The absolute detection limit (3σ) is 1.8 ng. Based on a sample volume of 500 mL, this value corresponds to a concentration detection limit 3.6 ng L^?1 TBT This method has been successfully applied to the analysis of TBT in sea water collected from Keelung and Kaohsiung harbors.