Evaluation of Pesticide Contamination of Ground Water in Two Agricultural Areas of Portugal

In two Portuguese agricultural areas, "Beira Litoral" and "Ribatejo e Oeste", several pesticides regularly applied in vineyards, maize, potato, tomato for industry, apple, pear and rice were detected in ground water. Atrazine was the most frequently detected, being found in 70% of the total of 79 sites selected in the year 2000, followed by its metabolites desethylatrazine and desisopropylatrazine with frequencies of detection, respectively, of 56% and 48% and by simazine (37%), alachlor (25%), metolachlor (24%) and metribuzin (15%). Other pesticides and metabolites i.e. 3,4-dichloroaniline, dimethoate, f and g -endosulfan, lindane, molinate and prometryn were also detected but at lower occurrences. Pesticides were detected mainly in ground water wells used for irrigation purposes, although in some locations they were also found in water wells used for human consumption. In this study, it was also observed a seasonal variation of pesticide residues in ground water of shallow and deep wells.     

Effect of viscosity of a liquid membrane containing oleyl alcohol on the pertraction of butyric acid

Solvent formulation is important in the optimization of the mass-transfer through supported liquid membranes (SLM) in pertraction and membrane extraction. Oleyl alcohol (OA) is frequently used as the solvent or diluent in the extraction of carboxylic acids. A disadvantage of OA is its relatively high viscosity of 28.32 mPa s at 25°C. This can be decreased by the application of a less viscous OA diluent, e.g. dodecane. The relationship between the ratio of the distribution coefficient of butyric acid (BA), D _F, and the viscosity of OA-dodecane solvents, µ, as extraction and transport characteristics, and the overall mass-transfer coefficient, K _p, through SLMs was analyzed. Dependence of the D _F/µ ratio on the OA concentration showed a maximum at the OA concentration of 15 mass % to 30 mass %. The OA concentration dependence of K _p for SLMs exhibited also a maximum at about 30 mass % and 20 mass % of OA at the BA concentration driving force of 0.12 kmol m^?3 and 0.3 kmol m^?3, respectively. Shifting of the maximum in K _p dependences towards lower OA concentrations by increasing the BA concentration driving force is in agreement with the D _F/µ ratio dependence. Using pure OA as the solvent or diluent is not preferable and a mixture of a low viscosity diluent with the OA concentration below 40 mass % should be used. The presented results show the potential of the D _F/µ ratio in the screening and formulation of solvents in extraction and SLM optimization.     

辉光放电电解等离子体引发合成高吸水性树脂

以淀粉、丙烯酸和腐殖酸钠为原料,以N,N-亚甲基双丙烯酰胺为交联剂,采用辉光放电电解等离子体在水溶液中引发聚合制备淀粉-聚丙烯酸/腐殖酸钠复合高吸水树脂。考察了放电电压、放电时间,单体与淀粉质量比、腐殖酸钠含量、交联剂、温度及中和度对树脂吸水率的影响。用红外光谱和热重分析分别对树脂进行了结构表征和稳定性测试,结果表明,在优化合成条件下,所得的复合树脂具有较高的吸水性和耐盐性,常温下对蒸馏水吸收量为862g/g,对0.9%NaCl溶液的吸收量为69g/g。     

埃罗替尼的合成

以N,N-二甲基甲酰胺和硫酸二甲酯反应生成的亚胺盐与3-乙炔基苯胺进行亲核反应及甲醇的消去,获得了制备埃罗替尼所需的重要中间体N’-(3-乙炔基苯基)-N,N-二甲基甲脒,收率为75.8%。再以此中间体与2-氨基-4,5-二(2-甲氧基乙氧基)苯甲腈通过Dimroth重排反应方便地制得了抗肿瘤药物埃罗替尼,总收率(以3-乙炔基苯胺计)为56.5%。与以往合成埃罗替尼的方法相比,该方法更经济、更绿色。     

Response surface optimisation applied to a headspace-solid phase microextraction-gas chromatography-mass spectrometry method for the analysis of volatile organic compounds in water matrices

A new method for the simultaneous determination of 12 volatile organic compounds (trans-1,2-dichloroethene, 1,1,1-trichloroethane, benzene, 1,2-dichloroethane, trichloroethene, toluene, 1,1,2-trichloroethane, tetrachloroethene, ethylbenzene, m-, p-, o-xylene) in water samples by headspace solid phase microextraction (HS–SPME)–gas chromatography mass spectrometry (GC–MS) was described, using a 100?µm PDMS (polydimethylsiloxane) coated fibre. The response surface methodology was used to optimise the effect of the extraction time and temperature, as well as the influence of the salt addition in the extraction process. Optimal conditions were extraction time and temperature of 30?min and ?20°C, respectively, and NaCl concentration of 4?mol?L^?1. The detection limits were in the range of 1.1?×?10^?3–2.3?µg?L^?1 for the 12 volatile organic compounds (VOCs). Global uncertainties were in the range of 4–68%, when concentrations decrease from 250?µg?L^?1 down to the limits of quantification. The method proved adequate to detect VOCs in six river samples.     

Hydroformylation and hydroalkylcarbonylation of 3,4-dihydro[2H]pyran catalysed by Co2(CO)8 under syngas conditions

In the cobalt-catalysed hydroformylation of 3,4-dihydro[2H]pyran, the influence of different reaction parameters such as time, pressure, triphenylphosphine addition, catalyst and substrate concentration has been investigated. 2-formyl-tetrahydropyran, tetrahydropyran and a hydroalkylcarbonylation product were the main reaction products. The selectivity towards 2-formyl-tetrahydropyran formation is favoured at constant catalyst and substrate concentration. The coordination of the pyran’s oxygen to the cobalt atom seems to be an important intermediate for the formation of 2-formyl-tetrahydropyran. Different substrate or catalyst concentrations promote the formation of other reduced products. The addition of triphenylphosphine to the catalyst leads to a less active species, which decreases the yield and promotes the hydroalkylcarbonylation reaction.     

Mechanism of α-acetyl-γ-butyrolactone synthesis

The mechanism of α-acetyl-γ-butyrolactone (ABL) synthesis from γ-butyrolactone (GBL) and ethyl acetate (EtOAc) was explored by detecting the material changes involved and the enthalpies of formation of the synthons, products, and possible intermediates were calculated using the density functional theory. GBL forms a carbanion of γ-butyrolactone by losing an α-H under strongly alkaline conditions. ABL is then obtained via two reaction mechanisms. One of the reaction mechanisms involves direct reaction of the carbanion of GBL with EtOAc to produce ABL. The other involves the formation of a carbanion of α-(2-hydroxy-tetrahydrofuran-2-yl)-γ-butyrolactone through the reaction of two molecules of GBL, and the subsequent combination of this anion with EtOAc to produce ABL. ABL is thus formed through the above two kinds of competitive ester condensation reactions. It is unnecessary to take into account synthons’ local thickness, and their self-condensation under these conditions. Both reactions of the carbanion of GBL with EtOAc and GBL are exothermic, so the control of their reaction rate is the key to their security. Considering the reasons above, this work applied synthon as the solvent, and avoided environmental pollution by alkylbenzene; also, accidents such as red material and fire were avoided by specific surface area of sodium metal control. Effective isolation of the organic and aqueous phases was performed using the salting out method. Thus, an environmentally friendly, safe, simple, and efficient new method for the synthesis of ABL with the yield higher than 90 % has been established.     

Synthesis of α-Metoylene-γ-Lactones in Furanosidic Systems

Abstract

Synthesis of stereoisomeric α-methylene-γ-lactones in furanose-and furanuronoamide derivatives was easily accomplished by Reformatsky Reaction with ethyl bromcmethylacrylic ester and zinc. Pyridinium chlorochromate/3Å molecular sieve powder showed to be an excellent reagent for the oxidation of secondary hydroxyl groups of a furanose system and of α-hydroxy amides.     

Synthesis of S-Glycosyl Xanthates by Phase Transfer Catalyzed Substitution of Glycosyl Halides

Abstract

Peracetylated glycosyl- and glycobiosyl bromides and chlorides 1-4 including acetochloroneuraminic acid 5 were stereoselectively transformed into their corresponding S-glycosyl xanthates 6-10 in high yield (91-98%) under phase transfer catalyzed conditions. The reactions occurred at room temperature using tetrabutylammonium hydrogen sulfate as the catalyst. The substitutions gave complete inversion of configuration and thus proceeded by an S_N2 type mechanism. Changing the organic solvent from methylene chloride to ethyl acetate had no detrimental effect on the outcome of the reactions but avoided an undesirable side reaction between the xanthate anion and methylene chloride.     

Highly transparent silica monoliths embedded with high concentration oxide nanoparticles

Silica monoliths embedded with high concentration of γ-Fe₂O₃ or TiO₂ nanoparticles were prepared by a sol–gel procedure designed according to the inherent properties of oxide colloids. In the first step, highly dispersible oxide nanoparticles were produced using an in situ modification sol–gel strategy. Then, these particles were re-dispersed in silicon alkoxide-containing solution to form a stable colloidal solution. The hydrolysis and condensation reactions of alkoxide were catalyzed by an organic base (morpholine). Due to the large molecule size of morpholine, the electric double layer on the surface of colloidal particles was not compressed by the ionized morpholine molecules. The colloidal solution thus remained stable during the gelation process. Through this procedure, oxide nanoparticles could be immobilized homogeneously in the pores of a silica matrix, forming highly transparent and crack-free monoliths.