Studies of the compositions of Pd(II) hydrolysis products

The characterization of the clusters formed on alkaline hydrolysis of [PdCl₄]^2– was performed using¹⁷O,²³Na,³⁵Cl,¹³³Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)₂] _n ·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 675–679, April, 1993.     

Microwave promoted methylation of plant polysaccharides

O-Methylation is of outstanding importance in structural polysaccharide chemistry. A novel method for the methylation of polysaccharides using microwave (MW) irradiation is described. Seed gum from Cyamopsis tetragonolobus (Guar) was fully methylated with dimethyl sulphate and sodium hydroxide using 100% microwave power for 4 min in 68% yield. The completely methylated seed gum thus obtained was hydrolyzed by 70% formic acid followed by 0.5N H₂SO₄ under full microwave power for 1.16 and 1.66 min, respectively. The partially methylated monosaccharides were separated and identified.     

Hydrolysis-condensation of tetraethoxysilane in nonparental solvents studied by GC-MS

Gas-chromatography coupled with mass spectrometry was used to investigate the hydrolysis and condensation of tetra-ethoxysilane (TEOS) in nonparental solvents (MeOH and nPrOH). In the presence of nonparental solvents, the reaction that advanced at highest rate is alkoxy group scrambling, that changes the precursor at the molecular level. Subsequent stages of hydrolysis-polycondensation process are essentially determined by the reactivity of the new molecular species formed.     

离子表面活性剂胶团对阿斯匹林碱水解反应的影响

离子表面活性剂胶团对阿斯匹林碱水解反应的影响史振民＊刘生昆张祝莲巩育军（延安大学化学系延安７１６０００）关键词表面活性剂，阿斯匹林，碱水解反应，胶团，抑制作用１９９６－０５－０４收稿，１９９６－０８－１２修回阿斯匹林（ＡＳＰ），学名为乙酰水杨酸，有较...     

Fluorinated,crosslinkable terpolymers based on vinylidene fluoride and bearing sulfonic acid side groups for fuel‐cell membranes

The radical terpolymerization of 8‐bromo‐1H,1H,2H‐perfluorooct‐1‐ene with vinylidene fluoride (VDF) and perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride is presented. Changing the feed compositions of these three fluorinated comonomers enabled us to obtain different random‐type poly[vinylidene fluoride‐ter‐perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride‐ter‐8‐bromo‐1H,1H,2H‐perfluorooct‐1‐ene] terpolymers containing various sulfonyl fluoride and brominated side groups. Yields higher than 70% were reached in all cases. The hydrolysis of the sulfonyl fluoride group into the ? SO₃Li function in the presence of lithium carbonate was quantitatively achieved without the content of VDF being affected, and so dehydrofluorination of the VDF base unit was avoided. These original terpolymers were then crosslinked via dangling bromine atoms in the presence of a peroxide/triallyl isocyanurate system, which produced films insoluble in organic solvents such as acetone and dimethylformamide (which totally dissolved uncured terpolymers). The acidification of ? SO₃Li into the ? SO₃H function enabled protonic membranes to be obtained. The thermal stabilities of the crosslinked materials were higher than those of the uncured terpolymers, and their electrochemical performances were investigated. According to the contents of the sulfonic acid side functions, the ion‐exchange capacities ranged from 0.6 to 1.5 mequiv of H⁺/g, whereas the water uptake and conductivities ranged from 5–26% (±11%) and from 0.5 to 6.0 mS/cm, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4566–4578, 2006     

Moisture sorption, transport, and hydrolytic degradation in polylactide

Management of moisture penetration and hydrolytic degradation of polylactide (PLA) is extremely important during the manufacturing, shipping, storage, and end-use of PLA products. Moisture transport, crystallization, and degradation, in PLA have been measured through a variety of experimental techniques including size-exclusion chromatography, differential scanning calorimetry, and X-ray diffraction. Quartz crystal microbalance and dynamic vapor sorption experiments have also been used to measure moisture sorption isotherms in PLA films with varying crystallinity. A surprising result is that, within the accuracy of the experiments, crystalline and amorphous PLA films exhibit identical sorption isotherms.     

Comparative kinetics of phospholipase A2 action on liposomes and monolayers of phosphatidylcholine spread at the air-water interface

A detailed kinetic model describing the surface transformation of spread liposomes along with their enzymatic hydrolysis was developed. The model was applied to the hydrolysis of the long-chain phosphatidylcholine generating reaction products which remain at the interface and to medium-chain substrates from which the products desorb rapidly into the bulk phase. The overall kinetic constants of the hydrolysis in liposomal systems were compared with those obtained with monolayers under barostatic conditions. The values of the interfacial Michaelis-Menten constant were estimated.     

Synthesis of 1,2-bis(methoxyamino)cycloalkanes from alicyclic 1,2-bis(hydroxyamines)

Derivatives of 1,4-dihydroxypiperazine-2,3-dione were obtained by reaction of cis-1,2-bis(hydroxyamino)cycloalkanes with diethyl oxalate. Their alkylation with CH₂N₂ or Mel afforded 1,4-dimethoxypiperazine-2,3-diones. Hydrolysis of the latter gave 1,2-bis(methoxyamino)cycloalkanes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 925–929, April, 1996.     

Structure of polynuclear palladium(ii) hydroxocomplexes formed upon alkaline hydrolysis of palladium(ii) chloride complexes

The structure of polynuclear Pd^II hydroxocomplexes (PHC) formed as a result of alkaline hydrolysis of Pd^II chloride complexes was studied by EXAFS, SAXS, and TEM methods. It is established that in aqueous solutions a hydroxocomplex particle is a filament curled into a ball containing about 100 Pd atoms. The filament consists of planar coordination squares of PdO₄ units linkedvia one or two oxygen bridges of different geometry. Aging of samples results in an increase in the number of single bridging ligands and a decrease in the diameter of particles. Interatomic distances around palladium atoms were determined.Translated fromIzvestiya Akademii Nauk. Seriya Khimlcheskaya, No. 10, pp. 1901–1905, October, 1995.     

胶束溶液中高氯酸二水(四胺)合钴(Ⅲ)配合物催化磷酸二酯水解的研究

本文合成了疏水性高氯酸二水（四胺）合钴（Ⅲ）配合物，研究了它与非离子表面活性剂Brij35形成的金属2胶束催化二（对硝基苯酚）磷酸二酯水解的动力学及其机理。结果表明此金属胶束对磷酸二酯水解的速率大约提高10^4倍，这主要是由于表面活性剂胶束的pH效应和浓聚效应所致，暗示着顺式二水类配合物形成的金属胶束是一个潜在的磷酸二酯水解剪切的催化剂。