Polymerization of 1,3‐dienes with functional groups. III. Free‐radical polymerization of N,N‐diethyl‐2‐methylene‐3‐butenamide

Free‐radical homo‐ and copolymerization behavior of N,N‐diethyl‐2‐methylene‐3‐butenamide (DEA) was investigated. When the monomer was heated in bulk at 60 °C for 25 h without initiator, rubbery, solid gel was formed by the thermal polymerization. No such reaction was observed when the polymerization was carried out in 2 mol/L of benzene solution with with 1 mol % of azobisisobutyronitrile (AIBN) as an initiator. The polymerization rate (R_p) equation was R_p ∝ [DEA]^1.1[AIBN]^0.51, and the overall activation energy of polymerization was calculated 84.1 kJ/mol. The microstructure of the resulting polymer was exclusively a 1,4‐structure where both 1,4‐E and 1,4‐Z structures were included. From the product analysis of the telomerization with tert‐butylmercaptan as a telogen, the modes of monomer addition were estimated to be both 1,4‐ and 4,1‐addition. The copolymerizations of this monomer with styrene and/or chloroprene as comonomers were also carried out in benzene solution at 60 °C. In the copolymerization with styrene, the monomer reactivity ratios obtained were r₁ = 5.83 and r₂ = 0.05, and the Q and e values were Q = 8.4 and e = 0.33, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 999–1007, 2004     

Electrochemical Detection of As(III) via Iodine Electrogenerated at Platinum,Gold, Diamond or Carbon‐Based Electrodes

The reaction of iodine, electrogenerated from iodide, is used for the detection of As(III) via electrocatalytic reaction in the diffusion layer of a boron‐doped diamond electrode. The merits of this electrode material for this purpose (over platinum, gold or glassy carbon) are demonstrated and the kinetics of the reaction between I₂ and As(III) in acid reported.     

A novel greener glycosidation using an acid-ionic liquid containing a protic acid

The glycosidations of glucopyranosyl diethyl phosphite and alcohols using an ionic liquid, 1-n-hexyl-3-methylimidazolium trifluoromethanesulfonimidide (C₆mim[NTf₂]) containing a protic acid, trifluoromethanesulfonimide (HNTf₂), as a novel solvent-catalyst system, effectively proceeded under mild conditions to give the corresponding glycosides in good to high yields. Furthermore, this acid-ionic liquid combination could be reused many times for the glycosidations without any loss in efficiency.     

ICP－AES同时测定土壤和沉积物中全硼与其它微量及常量元素

本文阐述了用Ｈ３ＰＯ４、ＨＦ、ＨＮＯ３及ＨＣｌＯ４消化土壤及水系沉积物样品。其中磷酸的作用是避免在样品消化过程中硼的挥发损失。应用电感耦合等离子体发射光谱（简称ＩＣＰ－ＡＥＳ）同时测定样品中全硼及其它微量、常量元素的含量。该法具有高的准确度及精密度。方法快速、简便、适合土壤和沉积物的多元素测定。     

BNCT蒙特卡洛剂量计算的混合网格算法研究

在硼中子俘获治疗(BNCT)的蒙特卡洛(MC)剂量计算中,通常使用单一的网格模式,如16mm,8mm,4mm.使用细网格计算资源太大,使用粗网格,计算精度不够,为此,根据粒子穿透深度和计数量的变化梯度,采用混合网格模拟计算,达到了细网格的精度,时间仅为细网格的37%.     

MgBr2·OEt2 mediated protection of alcohols with hexamethyldisilazane: An efficient catalytic route for the preparation of silyl ethers under solvent-free conditions

Various types of alcohols and phenols were rapidly protected by hexamethyldisilazane in good to excellent yields at room temperature in the presence of catalytic amount of magnesium bromide ethyl etherate under solvent-free conditions. Good to excellent chemoselectivity was demonstrated for competitive protection of primary hydroxyls in the presence of secondary and tertiary alcohols. Highly selective protection of phenols in the presence of aromatic amines was also demonstrated successfully.     

Stereocontrol of diene polymers by topochemical polymerization of substituted benzyl muconates and their crystallization properties

We report the stereocontrol of diene polymers by the topochemical polymerization of alkoxy-substituted benzyl muconates in the solid state. A monomer stacking structure is controlled by the weak intermolecular interactions in the monomer crystals, depending on the structure and position of the alkoxy-substituent. The translational and alternating types of molecular stacking structures in a column provide diisotactic and disyndiotactic polymers, respectively, by the solid-state polymerization under UV and γ-ray irradiation. On the other hand, the meso and racemo structures of the resulting polymers are determined by the molecular symmetry of the used muconate monomers. The various substituted benzyl ester polymers are transformed into the same ethyl ester polymers with the four types of tacticities. The structure and crystallization behavior of the substituted benzyl ester polymers as well as the ethyl ester polymers have been revealed in detail. We clarify the effects of the tacticity on the crystallization property of the stereoregular polymuconates. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4952–4965, 2006     

Excess isentropic compressibility and speed of sound of the ternary mixture 2-propanol + diethyl ether + n-hexane and the constituent binary mixtures at 298.15 K

Speed of sound and densities of the ternary mixture 2-propanol + diethyl ether + n-hexane and also the binary mixtures 2-propanol + diethyl ether and 2-propanol + n-hexane have been measured at the entire composition range at 298.15 K. The excess isentropic compressibilities and the excess speed of the sound have been calculated from experimental densities and speed of sound. These excess properties of the binary mixtures were fitted to Redlich-Kister equation, while the Cibulka’s equation was used to fit the values related to the values to the ternary system. These excess properties have been used to discuss the presence of significant interactions between the component molecules in the binary mixtures and also the ternary mixtures. Speed of sound of the binary mixtures and the ternary mixture have been compared with calculated values from free length theory (FLT), collision factor theory (CFT), Nomoto’s relation (NR), Van Deal’s ideal mixing relation (IMR) and Junjie’s relation (JR). The results are used to compare the relative merits of these theories and relations in terms of the root mean square deviation relative (RMSD_r).     

环己酮肟在改性氧化锆催化剂上的Beckmann重排反应Ⅱ．影响重排反应的若干因素

环己酮肟在改性氧化锆催化剂上的Ｂｅｃｋｍａｎｎ重排反应Ⅱ．影响重排反应的若干因素程时标徐柏庆唐守平蒋山蔡天锡王祥生（大连理工大学化工学院化学系，大连１１６０１２）关键词氧化硼，氧化锆，负载型催化剂，环己酮肟，Ｂｅｃｋｍａｎｎ重排反应，己内酰胺前文［１...     

FT IR ATR Study of Molecular Interactions in the Urea/Dimethyl Sulfoxide and Urea/Diethyl Sulfoxide Binary Systems

FT IR ATR spectra of urea/dimethyl sulfoxide and urea/diethyl sulfoxide mixtures in the S=O and N—H stretching vibration regions at different molar ratios have been measured. On the basis of the band deconvolution data, various types of intermolecular associated forms, including dimers and hydrogen-bonded urea–sulfoxide complexes, have been revealed. The latter has been confirmed also by ab initio calculations.