Preparation of substituted benzoyltrimethylsilanes by the palladium-catalyzed silylation of substituted benzoyl chlorides with hexamethyldisilane

A direct preparative route to benzoyltrimethylsilane has been found by the reaction of benzoyl chloride with hexamethyldisilane in the presence of a specified palladium(II) complex as catalyst.     

Regioselective 1,4-addition of nucleophiles to 1,3-diene monoepoxides catalyzed by palladium complex

1,3-Diene monoepoxides react with nucleophiles in the presence of palladium complex as a catalyst under neutral conditions to give 1,4-adducts selectively. The 1,4-adducts are allylic alcohols and there is a possibility of another nucleophilic attack. Ester of Monarch butterfly pheromone was prepared.     

A novel method for preparation of 2-(methyl- or phehnylthio)alkanoic esters

Ethyl 2-acetylalkanoate gave ethyl 2-(methyl- or phenylthio)alkanoate in high yield on treatment wiht CH₃SSO₂CH₃, PhSSO₂Ph, or PhSSPh in the presence of small excess of EtONa in EtOH. Application of the present method to synthesis of pellitorine and the queen substance is also described.     

Kinetics and mechanism of the reduction of 1,10-phenanthroline—copper(II) complex

The cyclic voltammetric study of 1,10-phenanthroline—copper(II) complex was carried out in acidic buffer solution. It was found from the current—mole ratio (copper (II): 1,10-phenanthroline) relationship that the maximum coordination number of 1,10-phenanthroline—copper(II) complex was four under the present experimental condition. The reduction mechanism and kinetics of copper(II) was studied in the presence of various concentrations of 1,10-phenanthroline.     

Regioselective oxidation of internal olefins bearing neighboring oxygen functions by means of palladium catalysts. Preparation of β-alkoxy or acetoxy ketones from allyl and homoallyl ethers or esters

A new preparative method of β- and γ-alkoxy (acetoxy) ketones, which are important precursors of vinyl ketones and 1,4-diketones, respectively, is presented. With PdCl₂/CuCl/O₂ or PdCl₂/p-benzoquinone catalyst system, internal olefins bearing allylic alkoxy or acetoxy group underwent regioselective oxidation to form the corresponding β-alkoxy or β-acetoxy ketones. Similarly, γ-acetoxy ketones were obtained from homoallyl acetates having internal olefins with high regioselectivity.     

Effect of the protonation level of poly(o-phenylenediamine) (PoPD) on the ac impedance of humidity-sensitive PoPD/poly(vinyl alcohol) composite film

A composite film consisting of poly(o-phenylenediamine) (PoPD) and poly(vinyl alcohol) (PVA) has been prepared, and the effect of the protonation level of PoPD on the response of the composite to humidity been investigated by ac impedance measurements. The electrochemical system of the PoPD/PVA composite in a humid atmosphere is represented by an electrochemical equivalent circuit containing film (R_film, C_film), Warburg (W) and interfacial (R_ct, C_dl) impedance. R_film was increased with decreasing protonation level of the PoPD in relative humidity regions higher than 40%, but it was almost independent of the protonation level in humidity regions lower than this percentage.     

Uptake of alkali and alkaline earth metal ions into electrochemically pretreated glassy carbon fibres by flow-through electrolysis

When glassy carbon fibres are used, alkali and alkaline earth metal ions are adsorbed in the micropores which are created or activated by oxidative treatment of the fibres. The average pore radius was estimated to be 2 nm by nitrogen adsorption experiments. Uptake was studied with a flow system consisting of a flow-through carbon-fibre electrode; a dropping mercury electrode at the end of the flow line monitored changes in the metal ion concentrations. The ions were taken up at negative potentials and released at positive potentials. The amount taken up increased in the sequence Na⁺ < Li⁺ < H⁺, suggesting that the ions were desolvated before entering the pore system.     

Synthesis of optically active (+)-19-nortestosterone by asymmetric bis-annulation reaction

Michael reaction of 1,7-pctadien-3-one with 2-methylcyclopentane-1,3-dione, followed by intramolecular aldol condensation promoted by L-amino acids produced the optically active (+)-4-(3-butenyl)-7a-methyl-5,6,7,7a-tetrahydroindane-1,5-dione in high chemical and optical yields. The PdCl₂-catalyzed oxidation of the terminal double bond gave the methyl ketone, which had 76% optical purity and was made 100% optically pure by recrystallization. Then aldol condensation afforded the tricyclic ketone, which was alkylated with 3-butenyl iodide to afford (?)-3β-t-butoxy-2,3,3a,4,5,7,8,9,9aβ,9bα-decahydro-6-(3-butenyl)-3aβ-methyl-1H-benz[e]inden-7-one. The synthesis of this compound means the total synthesis of (+)-19-nortestosterone.     

Emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. I. Effects of reaction conditions on the polymerization rate and polymer molecular weight

The radiation-induced emulsifier-free emulsion polymerization of tetrafluoroethylene was carried out at an initial pressure of 2–25 kg/cm², temperature of 30–110°C, and under a dose rate of 0.57 × 10⁴?3.0 × 10⁴ rad/hr. The rate of polymerization was shown to be proportional to 1.0 and 1.3 powers of the dose rate and initial pressure, respectively, and is maximal at about 70°C. The molecular weight of polytetrafluoroethylene (PTFE) lies in the range of 10⁵?10⁶, increases with reaction time in the early stage of polymerization, and is maximal at 70°C but is almost independent of the dose rate. An interesting discovery is that PTFE, a hydrophobic polymer, forms as a stable latex in the absence of emulsifier. When PTFE latex coagulates during polymerization under certain conditions, the polymerization rate decreases, probably because polymerization proceeds mainly on the polymer particle surface. The observed rate acceleration and successive increase in polymer molecular weight may be due to slow termination of propagating radicals in the rigid PTFE particles.     

Formation and Crystallization Behavior of Gels in the Na2O-SiO2-TiO2-ZrO2 System

SiO₂-TiO₂-ZrO₂ and 5Na₂O·95(SiO₂ + TiO₂ + ZrO₂) gels were synthesized and role of Na₂O in gel formation and crystallization behavior of gels were studied. From Si(OC₂H₅)₄, Ti(iso-OC₃H₇)₄, Zr(n-OC₃H₇)₄ and NaOCH₃ solutions in EtOH without H₂O, transparent and opaque gels were obtained. Opaque bulk gels, rich in TiO₂ or ZrO₂ composition in Na₂O containing SiO₂-TiO₂-ZrO₂ system, contain agglomerated spherical particles of diameter small <10 m, in contrast with opaque gels having large particles <30 m in alkali-free SiO₂-TiO₂-ZrO₂ system. Crystallization temperature (Tc) was measured by DTA on dried gels. Compared with the alkali-free SiO₂-TiO₂-ZrO₂ gels, 5 mol% Na₂O containing gels gave lower Tc in SiO₂ rich compositions and higher in TiO₂ rich or ZrO₂ rich compositions.