Kinetic study of the radical polymerization behavior of N‐(1‐phenylethylaminocarbonyl)methacrylamide

Polymerization of N‐(1‐phenylethylaminocarbonyl)methacrylamide (PEACMA) with dimethyl 2,2′‐azobisisobutyrate (MAIB) was kinetically studied in dimethyl sulfoxide (DMSO). The overall activation energy of the polymerization was estimated to be 84 kJ/mol. The initial polymerization rate (R_p) is given by R_p = k[MAIB]^0.6[PEACMA]^0.9 at 60 °C, being similar to that of the conventional radical polymerization. The polymerization system involved electron spin resonance (ESR) spectroscopically observable propagating poly(PEACMA) radical under the actual polymerization conditions. ESR‐determined rate constants of propagation and termination were 140 L/mol s and 3.4 × 10⁴ L/mol s at 60 °C, respectively. The addition of LiCl accelerated the polymerization in N,N‐dimethylformamide but did not in DMSO. The copolymerization of PEACMA(M₁) and styrene(M₂) with MAIB in DMSO at 60 °C gave the following copolymerization parameters; r₁ = 0.20, r₂ = 0.51, Q₁ = 0.59, and e₁ = +0.70. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2013–2020, 2005     

Preparation of LiNiO2 and LiM y Ni1- y O2 (M=Co,Al) films by electrostatic spray deposition

Syntheses of LiNiO₂, LiCo_0.5Ni_0.5O₂, and LiAl_0.25Ni_0.75O₂ as thin films were carried out by electrostatic spray deposition (ESD) onto a gold substrate. Single-phase LiNiO₂ film was obtained using a precursor solution of Li(OCOCH₃)+Ni(OCOCH₃)₂/ethanol, and by heating the deposit at 700 °C under an oxygen stream. In the case of cobalt or aluminum doping, Co(NO₃)₂/ethanol or Al(NO₃)₃/ethanol were added to the precursor solution in a given ratio. X-ray diffractometry revealed that all films had a crystal structure of space group R3ˉm; a=2.879, c=14.197 ? for LiNiO₂; a=2.844, c=14.152 ? for LiCo_0.5Ni_0.5O₂; a=2.855, c=14.148 ? for LiAl_0.25Ni_0.75O₂ (in hexagonal setting). Although these products were highly porous, it was observed that the average film thickness of LiNiO₂ increased almost proportionally with the deposition time. Electrochemical measurements (cyclic voltammetry, charge/discharge measurement at a constant current) were carried out in organic solutions of LiClO₄ (1 mol dm⁻³ LiClO₄/propylene carbonate+ethylene carbonate). The results indicated that thin films fabricated by ESD were electrochemically active for lithium ion extraction/insertion. The effect of cobalt or aluminum doping on the voltammograms is also described. Received: 1 April 1998 / Accepted: 23 July 1998     

Optimal water concentration for aqueous Li+ intercalation in vanadyl phosphate

Development of high-performance aqueous batteries is an important goal for energy sustainability owing to their environmental benignity and low fabrication costs. Although a layered vanadyl phosphate is one of the most-studied host materials for intercalation electrodes with organic electrolytes, little attention has been paid to its use in aqueous Li⁺ systems because of its excessive dissolution in water. Herein, by controlling the water concentration, we demonstrate the stable operation of a layered vanadyl phosphate electrode in an aqueous Li⁺ electrolyte. The combination of experimental analyses and density functional theory calculations reveals that reversible (de)lithiation occurs between dehydrated phases, which can only exist in an optimal water concentration.

We demonstrate aqueous Li⁺ intercalation chemistry of vanadyl phosphate in the form of monohydrates, which are only stable in an optimal water-concentration environment.     

Thermal decomposition of cyclic organic peroxides in pure solvents and binary solvent mixtures

The thermal decomposition reaction of acetone cyclic triperoxide, acetone cyclic diperoxide, 4‐heptanone cyclic diperoxide, and pinacolone cyclic diperoxide ca. 0.02 M was studied in pure solvents (acetone and 1‐propanol) and in binary mixtures of acetone/1‐propanol at 150°C. The kinetics of each system was explored by gas chromatography (GC) at different solvent compositions. The reactions showed a behavior accordingly with a pseudo‐first‐order kinetic law up to at least 90% peroxide decomposition. The main organic products derived from these thermolysis reactions were detected by GC analysis. Among them, the corresponding ketones, methane, ethane, and propane were the main identified products. The rates of decomposition of pinacolone diperoxide in the pure solvents were practically independent of the solvent characteristics, so it was of no interest to analyze its kinetic behavior in binary solvent mixtures. In acetone/1‐propanol mixtures, the solvation effect on the cyclic peroxides derived from 4‐heptanone and acetone molecules was slightly dominated by specific interactions between 1‐propanol and a diradical‐activated complex initially formed. This species was preferentially solvated by 1‐propanol instead of acetone. Specific interactions between the O atoms from the peroxidic bond and the H from the OH in 1‐propanol can be taken into account. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 347–353, 2010     

Numerical solutions of two non-linear simultaneous equations

In this article, we shall give practical and numerical representations of inverse mappings of two-dimensional mappings (of the solutions of two non-linear simultaneous equations) and show their numerical experiments by using computers. We derive a concrete formula from a very general idea for the representation of the inverse functions.     

The First Catalytic Asymmetric Nitro-Mannich-Type Reaction Promoted by a New Heterobimetallic Complex

The best ratio is 1:1:3 for the components Yb, K, and binaphthol in the new heterobimetallic complex, which efficiently catalyzes an asymmetric nitro-Mannich-type reaction. The desired nitro-Mannich products 2 are obtained with up to 91 % ee starting from N-phosphinoyl imines 1.     

Efficient synthesis of a novel, twisted and stable, electroluminescent "twistacene"

[reaction: see text] A twistacene, 6,8,15,17-tetraphenyl-1.18,4.5,9.10,13.14-tetrabenzoheptacene (3), was synthesized using a mild and novel bisbenzyne precursor. It was characterized by X-ray crystallography, NMR, UV-vis, and IR spectroscopies, as well as cyclic voltammetry and DFT calculations. The heptacene derivative possesses a nonpropeller twist topology and is unusually stable for a highly conjugated oligoacene. In addition, it is fluorescent, with a quantum efficiency of 15%. Distortion from planarity, mostly due to the phenyl substituents, causes only marginal changes in electronic properties and is beneficial for redox reversibility, which is required for efficient OLED devices.     

Preparation of β-Cyclodextrin Derivatives Possessing Two Trimethylammonio Groups on Their Primary Hydroxy Sides as Chiral Guest Selectors

Three isomers of -cyclodextrin derivatives 2a–c possessing two trimethylammonio groups on their C(6) atoms were prepared by reaction of the corresponding regioisomers of diamino compounds with methyl iodide. These derivatives recognize chiral guests through three-point interactions composed of both Coulomb interactions by the two cationic moieties and hydrophobic interaction by the molecularcavity.