Efficient synthesis of p-bis-(chlorodifluoromethyl)benzene

Selective, high yield partial fluorination of p-bis-(trichloromethyl)benzene to p-bis-(chlorodifluoromethyl)benzene has been accomplished by warming a slurry of the p-bis-(trichloromethyl)benzene in anhydrous HF which also contains a small quantity of inert solvent, such as 1,2-dichloroethane.     

酚醛型氰酸酯与双酚A型环氧共固化反应的FTIR研究

在恒温固化条件下,通过FTIR跟踪方法,研究了酚醛型氰酸酯与双酚A型环氧共固化反应的路径及其反应机理.共固化体系的反应过程包括在150℃及其以下温度,主要发生的是氰酸酯的三嗪环化固化反应,其中三嗪环化固化反应由于环氧的加入,反应速率被极大地提高了;同时,酚醛型氰酸酯中的氨基甲酸酯类杂质与环氧发生开环聚合反应,引起环氧官能团产生弱而持续的消耗.但在此阶段,酚醛型氰酸酯与环氧之间没有化学反应发生;在180℃及其以上温度,三嗪环和环氧发生反应,异构为异氰脲酸环结构,并进一步反应生成唑啉酮环结构,由于该反应的发生,促进了环氧官能团的消耗速度,在环氧官能团的转化率-时间图中,出现倒S曲线;在三嗪环的转化率图中,出现一个极大值后再降落的曲线.反应温度的提高有利于促进酚醛型氰酸酯与环氧之间的共固化反应,特别是当反应温度为220℃时,氰酸酯官能团和环氧官能团的消耗、三嗪环和唑啉酮环的生成均以较快的速率进行,—OCN生成三嗪环的转化率可以较容易地达到1,而唑啉酮环的转化率不超过0.5.     

Chemical analysis for small amounts of horseradish peroxidase using “porphyrinogen” as a chromogenic reagent

The properties of porphyrinogen as a new chromogenic reagent were examined. 5,10,15,20-Tetrahydro-tetraphenylporphyrinogen (TPPN) is changed to 5,10,15,20-tetraphenylporphine (TPP) by the oxidative reaction involving six electrons, and its formation of the porphine ring significantly increased the absorbance in the Soret band.The horseradish peroxidase (HRP) accelerated the oxidative reaction as a catalyst and the increment of absorbance depended upon the increase in the concentration of HRP. The reaction proceeded in the presence of dissolved oxygen and in the neighborhood of pH 7. Based on these findings, a chemical analysis by catalytic action using HRP was developed.In the procedure for this determination, the difference in absorbance at 419 nm (ΔA₄₁₉=A_s−A_b, where A_s and A_b are the absorbances of the sample solution containing HRP and the blank solution without HRP after 30 min, respectively), was measured. The determination range of HRP, which was obtained from the ΔA₄₁₉—HRP concentration curve, was 0.05-1.0 mg/l. The relative standard deviation in the median of the calibration curve was 3.19% (seven determinations), and the detection limit (S/N=3) was 29 ng/l. Furthermore, when the proposed method was applied to the enzyme immunoassay, bisphenol A (BPA) was selectively and sensitivity determined.     

Two-dimensional TiO2 (001) nanosheets as an effective photo-assisted recyclable sensor for the electrochemical detection of bisphenol A

Electrochemical detection is an efficient method for the detection of Bisphenol A (BPA). Herein, a sensitive photo-electrochemical sensor based on two-dimensional (2D) TiO₂ (001) nanosheets was fabricated and then used for BPA electrochemical detection. Upon light irradiation, the 2D TiO₂ (001) nanosheets electrode provided a lower detection limit of BPA detection compared with an ambient electrochemical determination. The low detection limit is ∼5.37 nmol/L (S/N = 3). Furthermore, profiting from the photoelectric characteristics, the 2D TiO₂ (001) nanosheets electrode exhibits a nice regeneration property. After 45 min of light irradiation, the electrochemical signal was regenerated from 14.7% to 82.9% of the original signal at the 6^th cycle. This is attributed to the non-selective OH mediation produced by the 2D TiO₂ (001) nanosheets mineralizing anodic polymeric products and resuming surface reactive sites. This investigation indicates that photo-assistance is an efficient method to improve the electrochemical sensor for detecting BPA in water environments.     

双酚A人工抗原的光谱表征及免疫鉴定研究

双酚A(bisphenol A,BPA)是一种酚类环境雌激素,即使极低剂量残留对人类健康也有危害。为了建立其简单快速并适应现场检测的免疫分析方法,必须先合成它的人工抗原并进行鉴定。通过对双酚A进行结构修饰,用碳二亚胺将结构修饰了的双酚A与牛血清蛋白相偶联,经透析得到纯的双酚A人工抗原并冷冻干燥备用。然后用紫外光谱、红外光谱和免疫方法对人工抗原进行鉴定。结果表明,合成的人工抗原紫外光谱图中具有蛋白质和双酚A的特征吸收峰;人工抗原红外光谱图中呈现双酚A和牛血清蛋白的红外特征吸收峰;通过竞争ELISA试验表明用合成的人工抗原免疫的Balb/c小鼠血清中产生了双酚A的抗体。三种方法综合鉴定结果表明双酚A人工抗原合成成功,该人工抗原可以进一步用于制备抗双酚A的单克隆抗体。     

CHARACTERIZATION OF MELT-MIXED POLY(ETHYLENE-2,6-NAPHTHALATE) (PEN)/POLYCARBONATE (PC) BLENDS

ABSTRACT

Melt blending of poly(ethylene naphthalate) (PEN) and bisphenol A polycarbonate (PC) was performed without the addition of catalyst in a batch mixer at 290°C at various compositions. All the blends prepared exhibited a biphasic character and had very good mechanical properties, in some cases, even better than those of the respective pure constituents. This behavior was attributed to a copolymer formation in the mesophase, which effectively compatibilizes the system. The formation of a PEN/PC block copolymer was considered to be due to transesterification reactions between PEN and PC and was verified by extraction experiments and examination of the soluble and insoluble fractions by various spectroscopic techniques.     

pTSA-catalyzed condensation of xylenols and aldehydes under solvent-free conditions: One-pot synthesis of 9H-xanthene or bisphenol derivatives

A simple and efficient procedure for the synthesis of 9H-xanthene or bisphenol derivatives has been developed by one-pot condensation of xylenols with aromatic aldehydes in the presence of p-toluenesulfonic acid (pTSA) as a catalyst under solvent-free conditions at 100 °C. It is noteworthy that the condensation reaction of 3,5-xylenol with aldehydes produces 9H-xanthene derivatives, while the reaction with other xylenols leads to the corresponding bisphenol derivatives. Different types of aromatic aldehydes are used in the reaction and in every case the products were obtained in good to excellent yields. The structures of these compounds were established on the basis of IR, ¹H NMR, ¹³C NMR and CHN data.     

Synergistic Effect of Lithium Perchlorate and Sodium Hydroxide in the Preparation of Electrochemically Treated Pencil Graphite Electrodes for Selective and Sensitive Bisphenol A Detection in Water Samples

In this study, pencil graphite electrodes were activated electrochemically in the presence of different supporting electrolytes and used for the selective and sensitive determination of bisphenol A (BPA) in water samples. Synergistic effects of both LiClO₄ and NaOH supporting electrolytes on the performance of the electrochemically treated pencil graphite electrode (ETPGE) were demonstrated in the oxidation of BPA. The electrochemical behavior of BPA on the ETPGE showed two irreversible oxidation peaks at 0.744 V and 0.877 V (vs. SCE). The detection limit was determined to be 3.1 nM. This single‐use electrode is a very promising candidate to overcome the passivation problems arising from the oxidation of BPA. The analytical application of the ETPGE was performed in tap and river water samples.     

Electrochemical sensor based on f-SWCNT and carboxylic group functionalized PEDOT for the sensitive determination of bisphenol A

A simple,sensitive,and reliable method for the voltammetric determination of bisphenol A(BPA) by using carboxylic group functionalized single-walled carbon nanotubes(f-SWCNT)/carboxylic-functionalized poly(3,4-ethylenedioxythiophene)(PC4) complex modified glassy carbon electrode(GCE) has been successfully developed.The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques.The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS(0.1 mol/L,pH 7.0).The surface morphology of the 3D network of composite film is beneficial for the adsorption of analytes.Under the optimized conditions,the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L(R~2 = 0.9989),with a limit of detection of 0.032 μmol/L(S/N = 3).The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property of/-SWCNT and the extraordinary conductivity of PC4.Furthermore,the proposed modified electrode displays high stability and good reproducibility.The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.     

固相萃取-高效液相色谱-荧光检测法同时测定水中的壬基酚和双酚A

利用C18固相萃取柱富集和净化水样,采用高效液相色谱分离、荧光检测建立了水中的壬基酚（NP）和双酚A（BPA）的测定方法,并成功用于污水处理厂各处理单元出水的测定。不同加标水平的NP和BPA的回收率为95．3％～98．6％．其相对标准偏差为2、5％～3．7％。