Biginelli reaction in aqueous medium: a greener and sustainable approach to substituted 3,4-dihydropyrimidin-2(1H)-ones

An environmentally benign aqueous Biginelli protocol for the synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using polystyrenesulfonic acid (PSSA) as a catalyst has been achieved. These microwave-assisted reactions proceed efficiently in water in the absence of organic solvent, with simple filtration as the product isolation step.     

Insoluble eggshell matrix proteins--their peptide mapping and partial characterization by capillary electrophoresis and high-performance liquid chromatography

Avian eggshell matrix proteins were studied by two analytical approaches. Peptide mapping was done by trypsin and pepsin followed by collagenase cleavage; analyses were carried out by capillary electrophoresis and reversed-phase high-performance liquid chromatography (HPLC). Comparison of peptide maps obtained by both methods revealed a complex mixture of peptides in the insoluble layers of the eggshell; it was concluded that there are at least three different insoluble protein/peptide layers in the avian eggshell (cuticle, palisade, and mammillary layer). Partial characterization of peptides in each layer was made by HPLC-mass spectrometry analysis. There is an evidence that the eggshell insoluble proteins contain species susceptible to collagenase cleavage, however, the sequences split by this enzyme probably are not those typical for the main triple-helical core of collagenous proteins. It is proposed that the action of collagenase upon eggshell proteins is caused by the side effect of collagenase described previously with synthetic peptides. Some of the proteins present are probably glycosylated. Fatty acid content in the insoluble eggshell layers (after decalcification) was in the range of 2-4% (which reflected both lipid and lipoproteins bound fatty acids). Porphyrin pigments are dominant in the cuticle layer.     

利用电荷迁移反应测定头孢羟氨苄

提出一种基于电荷迁移反应简便可靠地测定头孢羟氨苄的分光光度法。在甲醇－乙醇介质中，头孢羟氨苄与氯冉酸于５０℃反应１５ｍｉｎ能够形成稳定的１：１络合物，其λｍａｘ＝５２８ｎｍ，线性范围为２０￣４００ｍｇ／Ｌ。用拟定的方法测定原粉和胶囊，结果与药典法一致。对浓度１００ｍｇ／Ｌ的药物１０次测定相对标准偏差为１．４％，样品的标准加入回收率为９９．０％￣１００．８％。     

Use of non-segmented flow,post-columns reaction detection with miniaturized HPLC systems

Summary The use of non-segmented flow, post-column reaction detection is evaluated for use with miniaturized HPLC. Non-segmented open-tubular reactors with internal diameters 0.1 mm to 0.25 mm and packed-bed reactors with internal diameters of 1 mm, filled with 5 and 10 m particles are evaluated theoretically and experimentally with respect to band broadening and pressure drop characteristics. An integrated system consisting of miniaturized HPLC (1 mm i. d.) columns and compatible hardware is described. An example of the separation of catecholamines is given.     

Mitsunobu reactions of nucleoside analogs using triisopropyl phosphite-DIAD

Herein, we report the use of triisopropyl phosphite (TIP) as an effective substitute for triphenylphosphine in the Mitsunobu reaction of nucleoside analogs. In addition, the use of triphenyl phosphite as an alternative reagent for the expensive hexamethylphosphorous triamide (HMPT) in the Véliz-Beal bromination protocol is reported.     

Chemical reaction dynamics of PeCB and TCDD decomposition: A tight‐binding quantum chemical molecular dynamics study with first‐principles parameterization

The decomposition reaction dynamics of 2,3,4,4′,5‐penta‐chlorinated biphenyl (2,3,4,4′,5‐PeCB), 3,3′,4,4′,5‐penta‐chlorinated biphenyl (3,3′,4,4′,5‐PeCB), and 2,3,7,8‐tetra‐chlorinated dibenzo‐p‐dioxin (2,3,7,8‐TCDD) was clarified for the first time at atomic and electronic levels, using our novel tight‐binding quantum chemical molecular dynamics method with first‐principles parameterization. The calculation speed of our new method is over 5000 times faster than that of the conventional first‐principles molecular dynamics method. We confirmed that the structure, energy, and electronic states of the above molecules calculated by our new method are quantitatively consistent with those by first‐principles calculations. After the confirmation of our methodology, we investigated the decomposition reaction dynamics of the above molecules and the calculated dynamic behaviors indicate that the oxidation of the 2,3,4,4′,5‐PeCB, 3,3′,4,4′,5‐PeCB, and 2,3,7,8‐TCDD proceeds through an epoxide intermediate, which is in good agreement with the previous experimental reports and consistent with our static density functional theory calculations. These results proved that our new tight‐binding quantum chemical molecular dynamics method with first‐principles parameterization is an effective tool to clarify the chemical reaction dynamics at reaction temperatures. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

CoTPP电化学催化原溴代环己烷的机理

以电化学循环伏安、现场ＥＳＲ电化学以及现场薄层电化学方法研究了电生Ｃｏ（Ｉ）ＴＰＰ与溴代五己烷的反机制。在ＤＭＦ中，Ｃｏ（Ⅱ）／Ｃｏ（Ⅰ）的氧化还原有明显的催化溴代环己烷还原的特片，反现场有自由基生成，反应产物之一是Ｃｏ－Ｃ键化合物，可以在１．３０Ｖ（ＳＣＥ）－电子还原，当存在ＣＨ２－ＣＨＣＮ时，。生成另一种Ｃｏ－Ｃ键化合物，该化合物在－１．１０Ｖ（ＳＣＥ）处一电子还原，证明溴代环己烷与Ｃｏ（Ｉ）     

含羟基芳基或氨基芳基的磷酰胺酯衍生物的合成

采用均相反应的方法合成了6个含羟基芳基或氨基芳基的磷酰胺酯衍生物:[(ClCH_2CH_2)_2NP(O)(OPh)(XArY)](X:O,NH;Y:m或p-OH或NH_2).用元素分析、红外光谱、氢核磁共振谱及质谱证实了它们的组成及结构.     

On-line enzymatic reaction,extraction, and chromatography of fatty acids and triglycerides with supercritical carbon dioxide

Supercritical carbon dioxide can be utilized both as an introduction solvent in capillary SFC and as a reaction medium; both possibilities are illustrated in this study. An off-line SFE unit was modified for on-line SFE-SFC. To facilitate rapid depressurization of the extraction cell and to prevent memory effects, a 6-port valve was installed at the outlet line of the extraction unit. An increased background signal was obtained when PEEK polymer was used in the construction of the extraction vessel; when stainless steel was used, the blanks improved. The synthesis of methyl esters and butyl esters of fatty acids from triglycerides in edible fat was examined using an immobilized lipase as a catalyst in on-line SFE-SFC. As a result of 30 minutes reaction – extraction time, high yields of fatty acid esters were obtained at a pressure of 150 bar and a temperature of 50°C.     

The Use of Adiabatic Calorimetry for the Process Analysis and Safety Evaluation in Free Radical Polymerization

Adiabatic calorimetry is a technique that has been introduced as an important approach to hazard evaluation of exothermically reactive systems. In this paper the free radical polymerization of methyl methacrylate (MMA) has been studied. One of the most important aspects of MMA polymerization is its exothermicity and autoaccelerating behaviour, these characteristics can generate the occurrence of a runaway reaction.In a runaway situation the reacting system is close to adiabatic behaviour because it is unable to eliminate the heat that is being generated. An even worse situation can be reproduced in the laboratory with the Phi-Tec pseudo-adiabatic calorimeter. Process design parameters that are usually calculated from thermodynamic data or using semiempirical rules, such as adiabatic temperature rise or maximum attainable pressure, can be directly determined.The existence of the ceiling temperature has been experimentally demonstrated.This revised version was published online in November 2005 with corrections to the Cover Date.