Effective refractive index and intermolecular forces associated with a phase of functional groups

Cases in which a functional groups form distinct phases are known in material science in general and specifically in polymer and surfactant sciences. To calculate the van der Waals forces associated with such phases there is a need to evaluate the refractive index of those phases. We expand and generalize a method to estimate the refractive index of such ‘functional group phase’ and discuss how to use the refractive indices to calculate the interaction energies associated with such functional group phases and thereby modify the total theoretically calculated van der Waals forces.     

Synthesis of novel 3,5-disubstituted-dihydroisoxazoles from methyl undec-10-enoate and isoxazoles,triazole and tetrazolo-triazole from methyl undec-10-ynoate

The efficient cycloaddition reactions were carried out to afford the novel 3,5-disubstituted-dihydroisoxazoles from methyl undec-10-enoate and isoxazoles, triazole and tetrazolo-triazole from methyl undec-10-ynoate. The reactions occurred under relatively mild conditions and afforded the desired products in good yields.     

Activation of hafnocene catalyzed polymerization of 1-hexene with MAO and borate

A study of 1-hexene polymerization with ethylene-bis(9-fluorenyl) hafnium dichloride has been carried out using two different cocatalyst systems, methyl-aluminoxane/trimethylaluminum (MAO/TMA) and tris-isobutyl-aluminum/N,N-dimethylanilinium tetrakis(pentafluorophenyl) borate (TIBA/borate). When MAO/TMA was used, 1-hexene polymerized into a low molar mass poly(1-hexene) with low catalytic activity. Activation with TIBA/borate increased polymerization activity drastically as well as the molar mass of the polymers. In order to analyze differences in the activity profiles, UV-Vis spectroscopy was employed to investigate ligand to metal charge transitions (LMCT) of the hafnocene dichloride during the activation process. The low catalytic activity and the fast chain transfer to the cocatalyst with MAO/TMA may originate from strong bonding between the metallocene cation and the MAO/TMA species thus obstructing monomer coordination and insertion.     

Separation of Phenols from the Leaves of Toona Sinensis (Meliaceae) by Capillary Electrophoresis

A micellar electrokinetic capillary chromatography (MEKC) method, using UV detection, was developed for the determination of polyphenols in Toona sinensis (Meliaceae); the procedure involved precipitation of polyphenols from the leaves of T. sinensis using methanol. The structures can be established with fifteen compounds including methyl gallate, gallic acid, kaempferol, quercitin, quercitrin, rutin, kaempferol‐glucoside, catechin, epicatechin, stearic acid, palmitic acid, β‐sitosterol, stigmasterol, β‐sitosteryl‐glucoside, and stigmasteryl‐glucoside by spectroscopic analysis. However, there has been no investigation to quantitate the polyphenols that form T. sinensis. Thus, seven polyphenols of T. sinensis with UV absorbance, catechin (C), epicatechin (EC), methyl gallate (MG), rutin (R), gallic acid (G), quercitrin (Q), and kaempferol (K) were separated within 10 min with a 40 cm uncoated fused‐silica column, with the RSD < 3% (migration times), voltage at 15 kV using this method. On‐column detection was carried out at 254 nm. The detection limit of this method for all analytes ranged from 19.5 to 0.02 μM (RSD < 3.1%). The method provided a rapid and sensitive identification of polyphenols of interest in T. sinensis and is suitable for biological activity studies.     

PbBr2晶体的折射率研究

本文报道了ＰｂＢｒ２晶体折射率主轴的方位和它的主折射率的测量。     

Persistence of fungitoxicity of two triorganotin(IV) compounds in soil

The persistence of triphenyltin chloride-triphenylphosphine oxide (Ph₃SnCl·Ph₃PO) and diphenylbutyltin bromide (Ph₂BuSnBr) in unsterilized sandy loam soil maintained in the dark at 60% of its water-holding capacity and at 27±2°C was studied over a period of 29 days. The percentage recovery of the compounds upon extraction with acetone immediately after application to soil was 60% for Ph₃SnCl·Ph₃PO and 9.8% for Ph₂BuSnBr. The half-lives of the compounds were 15 days for Ph₃SnCl·Ph₃PO and 14.2 days for Ph₂BuSnBr. After 29 days following application of the compounds in soil < 8.3 μg g^?1 of Ph₃SnCl·Ph₃PO and < 5.1 μg g^?1 of Ph₂BuSnBr remained in soil compared with the starting concentration of 50 μg of each compound per gram soil. The two triorganotin compounds were evidently easily degraded and the compounds may be applied every 2–3 weeks in the field at a rate of at least 0.005–0.01 kg ha^?1.     

A neutral Ni(II) acetylide-mediated radical polymerization of methyl methacrylate using the atom transfer radical polymerization method

A neutral nickel σ-acetylide complex [Ni(CCPh)₂(PBu₃)₂] (NBP) is used for possible atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in conjunction with an organic halide as an initiator [R-X: CCl₄, CH₃Cl, BrCCl₃, C₂H₅Br, and C₅H₉Br] in toluene at 80 °C. Among these initiating systems, BrCCl₃/NBP gave the best controlled radical polymerization of MMA and produced polymer with relatively narrow molecular weight distribution (M_w/M_n≈1.3). The ATRP of MMA is preliminarily identified by the following facts: (1) the present MMA polymerization initiated by BrCCl₃/NBP is completely hindered by the addition of TEMPO; (2) the conversion shows a typical linear variation with time in semilogarithmic coordinates; (3) the measured number-average molecular weights of polymer show a linear increase with conversion and agree closely with the theoretical values; (4) the resulting polymer chain contains a dormant carbon-halogen terminal.