4-甲氧基-2,3,5-三甲基吡啶的合成新方法

以2，3，5-三甲基吡啶为原料，经氧化，硝化，甲氧基化，脱离四步反应合成 4-甲氧基-2，3，5-三甲基吡啶，总收率76%，其结构经IR，~1H NMR，~(13)C NMR 确证。     

Surface adsorption behaviour of milk whey protein and pectin mixtures under conditions of air-water interface saturation

Milk whey proteins (MWP) and pectins (Ps) are biopolymer ingredients commonly used in the manufacture of colloidal food products. Therefore, knowledge of the interfacial characteristics of these biopolymers and their mixtures is very important for the design of food dispersion formulations (foams and/or emulsions). In this paper, we examine the adsorption and surface dilatational behaviour of MWP/Ps systems under conditions in which biopolymers can saturate the air-water interface on their own. Experiments were performed at constant temperature (20 °C), pH 7 and ionic strength 0.05 M. Two MWP samples, β-lactoglobulin (β-LG) and whey protein concentrate (WPC), and two Ps samples, low-methoxyl pectin (LMP) and high-methoxyl pectin (HMP) were evaluated. The contribution of biopolymers (MWP and Ps) to the interfacial properties of mixed systems was evaluated on the basis of their individual surface molecular characteristics. Biopolymer bulk concentration capable of saturating the air-water interface was estimated from surface pressure isotherms. Under conditions of interfacial saturation, dynamic adsorption behaviour (surface pressure and dilatational rheological characteristics) of MWP/Ps systems was discussed from a kinetic point of view, in terms of molecular diffusion, penetration and configurational rearrangement at the air-water interface. The main adsorption mechanism in MWP/LMP mixtures might be the MWP interfacial segregation due to the thermodynamic incompatibility between MWP and LMP (synergistic mechanism); while the interfacial adsorption in MWP/HMP mixtures could be characterized by a competitive mechanism between MWP and HMP at the air-water interface (antagonistic mechanism). The magnitude of these phenomena could be closely related to differences in molecular composition and/or aggregation state of MWP (β-LG and WPC).     

Photochromism of new unsymmetrical isomeric diarylethenes bearing a methoxyl group

Three new unsymmetrical isomeric diarylethenes having a methoxyl substituent at ortho‐, meta‐, and para‐position of the terminal benzene ring, namely 1‐(2,5‐dimethyl‐3‐thienyl)‐2‐[2‐methyl‐5‐(2‐methoxylphenyl)‐3‐thienyl]perfluorocyclopentene ( 1o ), 1‐(2,5‐dimethyl‐3‐thienyl)‐2‐[2‐methyl‐5‐(3‐methoxylphenyl)‐3‐thienyl]perfluorocyclopentene ( 2o ), and 1‐(2,5‐dimethyl‐3‐ thienyl)‐2‐[2‐methyl‐5‐(4‐methoxylphenyl)‐3‐thienyl]perfluorocyclopentene ( 3o ), have been synthesized. The substituent position effect of methoxyl group on their properties, including photochromism and fluorescence both in hexane solution and in PMMA film, and their electrochemical properties, were investigated in detail. These diarylethenes showed good photochromism both in solution and in PMMA film. For the same photochromic diarylethene backbone, the electron‐ donating methoxyl substituent can effectively depress the cyclization quantum yields and increase the cycloreversion quantum yields compared to those of diarylethenes bearing chlorine atoms reported previously. Diarylethenes 1o – 3o showed clear fluorescent switches by photoirradiation both in hexane and in PMMA film. In addition, cyclic voltammetry tests showed that the electron‐donating methoxyl group at different position on the terminal benzene ring had a significant effect on the electrochemical properties of these isomeric diarylethenes. Copyright © 2009 John Wiley & Sons, Ltd.     

支持向量机回归法在近红外光谱测定植物纤维原料中甲氧基含量中的应用

以26个植物纤维原料为实验材料,由20个样品作校正样品,采用径向基核函数方法对纤维原料中甲氧基含量与纤维原料样品近红外光谱进行支持向量机(SVM)回归建模.以所建SVM回归模型对6个纤维原料样品中甲氧基含量进行预测,回归模型的预测结果与采用改良的维伯克法确定的甲氧基含量的相关系数为0.977,预测样本集的标准偏差为0.43.将SVM回归模型的预测效果与PLS回归模型的预测结果进行比较,所建近红外光谱测定植物纤维原料中甲氧基含量的SVM回归模型可用于实际植物纤维原料样品的定量分析,且具有较好的分析效果.     

Theoretical study of methoxy group influence in the gas‐phase elimination kinetics of methoxyalkyl chlorides

The unimolecular gas‐phase elimination kinetics of 2‐methoxy‐1‐chloroethane, 3‐methoxy‐1‐chloropropane, and 4‐methoxyl‐1‐chloroburane has been studied by using density functional theory (DFT) methods to propose the most reasonable mechanisms of decomposition of the aforementioned compounds. Calculation results of 2‐methoxy‐1‐chloroethane and 3‐methoxy‐1‐chloropropane suggest dehydrochlorination through a concerted nonsynchronous four‐centered cyclic transition state (TS) to give the corresponding olefin. In the case of 4‐methoxyl‐1‐chloroburane, in addition to the 1,2‐elimination mechanism, the anchimeric assistance by the methoxy group, through a polar five‐centered cyclic TS, provides additional pathways to give 4‐methoxy‐butene, tetrahydrofuran and chloromethane. The bond polarization of the C? Cl, in the direction of C^δ+ ··· Cl^δ?, is the limiting step of these elimination reactions. The significant increase in rate together with the formation of a cyclic product tetrahydrofuran in the gas‐phase elimination of 4‐methoxyl‐1‐chloroburane is attributed to neighboring group participation of the oxygen of the methoxy group in the TS. The theoretical calculations show a good agreement with the reported experimental results. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

meso-四-(对甲氧基)苯基卟啉和meso-四-(对甲氧基)苯基卟啉的电化学性质

锌卟啉配合物;合成;meso-四-(对甲氧基)苯基卟啉和meso-四-(对甲氧基)苯基卟啉的电化学性质     

Synthesis and Crystal Structure of a Novel Supramolecular Compound [Mg(H_2O)_6](C_(16)H_(11)O_4SO_3)_2·10H_2O

IntroductionMolecularpolymerwithonedimensionalormultidimen sionalstructureassemblingthroughhydrogenbondsisanim portantresearchcontentinthesupramolecularchemistryandcrystalenginnering .1,2 Withthedevelopmentofnewtypefunctionalmaterialssuchasmolecularmagnetic ,selectedcatalysis ,reversiblecatalysis ,reversiblehost guestmolecular(ion)exchangeetc.,3themoleculardesignandsynthesishavealreadyattractedconsiderableattentioninsupramolecu larsystem .Thesupramolecularcomplexesandorganiccom poundscontainin…     

分子筛表面酸性对微波固相法制备ZnCl2/Y催化剂的影响

 采用XRD和原子吸收光谱法研究了微波作用下分子筛表面酸性对ZnCl2与Y分子筛固态相互作用的影响．结果表明，微波辐射可显著促进ZnCl2在分子筛表面分散，其分散阈值与分子筛表面酸性有关．随着分子筛表面酸量和酸强度增加，ZnCl2在分子筛表面的最大分散量减少，分散的ZnCl2与Y分子筛的固态离子交换量也减少；NaY型分子筛比HY分子筛更容易发生固态离子交换反应．考察了微波固相法制备的ZnCl2／HY催化剂在苯甲醚与乙酰氯酰化反应中的催化性能．结果表明，在分子筛表面分散的ZnCl2具有更高的催化活性及对甲氧基苯乙酮选择性．     

Synthesis and characterization of bis(methoxyl hydroxyl)-functionalized disiloxane and polysiloxane oligomers derivatives therefrom

With purpose to prepare waterborne polyurethane with improved performance, bis(methyoxyl hydroxyl)-functionalized polysiloxanes with different dimethylsiloxane segment length were prepared. The preparation includes three steps, the first is synthesis of 1,3-bis(glycidoxypropyl)tetramethyldisiloxane (compound I) via hydrosilylation of allylglycidyl ether with tetramethyldisiloxane, followed by a subsequent methoxylation of the resultant compound from the hydrosilylation to give 1,3-bis(3-(1-methoxy-2-hydroxypropoxy)propyl)tetramethyldisiloxane (compound II). Using this compound II and octamethylcyclotetrasiloxane (D₄), an equilibrium reaction was carried out to obtain the target Product III, i.e. bis(methoxyl hydroxyl)-functionalized polysiloxanes. The ratio of D₄/compound II was varied in order to prepare product III with different segment length consisting of dimethylsiloxane units. At each step, the outcome compounds were characterized through Infrared, ¹H NMR, ¹³C NMR as well as H-H and H-C Correlated Spectroscopy (COSY). The results showed that each step was successfully carried out and objective products were achieved. It was estimated that compound II was not exclusive in the methoxylation step. Characterizations of the compound II enabled us to give a reliable quantitative amount for the by-products for the first time. In addition, the molecular weights of the final product III with varying dimethylsiloxane length were estimated by hydroxyl group analysis, ¹H NMR and GPC, which showed a good agreement between the theoretical molecular weights and those from these tests.