Catalytic asymmetric alkylation of α-cyanocarboxylates and acetoacetates using a phase-transfer catalyst

The catalytic asymmetric alkylation of α-cyanocarboxylates and acetoacetates with an alkyl halide was performed under phase-transfer conditions to afford compounds which have a chiral quaternary carbon with up to 97% and 94% ee, respectively. As applications of this method, chiral 2-oxindole derivatives and a β-lactam derivative were synthesized.     

Rod-like liquid crystals of organic transition metal complexes. I. Reversible transformation between blue smectogen and red nematogen

Two novel types of transition-metal-containing liquid crystals, bis(p-n-koxydithiobenzoato)nickel(II) (abbreviated as (C_nO-DTB)₂Ni), and (p-n-alkoxydithiobenzoato)(p-n-alkoxyperthiobenzoato)nickel(II) (abbreviated as (C_nO-DTB)(C_nO-PTB)Ni), were synthesized. It was found that the (C_nO-DTB)₂Ni complex for n = 8 has smectic H and C mesophases, and that the (C_nO-DTB)₂Ni complexes for n = 4 and 8 easily transform into the corresponding monoperthio complexes, _nO-PTB)Ni, by heating at temperatures between 230°C and 285°C. It was confirmed that the transformation originates from an intermolecular reaction between the (C_nO-DTB)₂Ni complexes at high temperatures, and that the origin of the extra sulphurs in the resulting (C_nO-DTB)(C_nO-PTB)Ni complexes is the neighbouring (C_nO-DTB)₂Ni complexes. Interestingly, each of the (C_nO-DTB)(C_nO-PTB)Ni complexes (n = 4 and 8), has nematic mesophase and exhibits a unique double melting behaviour via the nematic phase, which is the first example in liquid crystals. The reversible transformation between the blue smectic rod-like (C_nO-DTB)₂Ni complex and the red nematic Λ-like (C_nO-DTB)(C_nO-PTB)Ni complex is possible.     

Computing the cores of strategic games with punishment–dominance relations

In this paper, we discuss the computational complexity of the strategic cores of a class of n-person games defined by Masuzawa (Int J Game Theory 32:479–483, 2003), which includes economic situations with monotone externality. We propose an algorithm for finding an α-core strategy of any game in this class which, counting the evaluation of a payoff for a strategy profile as one step, terminates after O(n ³· M) operations, where M is the maximum size of a strategy set of any of the n players. The idea underlying this method is based on the property of reduced games. This paper is based on a part of the doctoral dissertation of the author. The author thanks Mikio Nakayama, Masashi Umezawa, William Thomson, an associate editor, and the anonymous referee for their helpful comments, suggestions, and advice. Thanks are also due to Yukihiko Funaki for a comment that led the author to this subject. The author is responsible for errors and inadvertencies.     

In situ monitoring of the H concentration change near an electrode surface through electrolysis using slab optical waveguide pH sensor

The H⁺ concentration change was monitored near an electrode surface through an electrolysis using a slab optical waveguide technique. Indium tin oxide transparent electrode modified by porous insulating polymer to which methyl red was covalently immobilized was used as a guiding layer, and the absorbance change of the polymer film was monitored. H⁺ generation at the vicinity of the electrode through the oxidation of ascorbic acid could be monitored by this technique.     

Catalyst‐free synthesis of polyorganosiloxanes by high temperature and pressure water. II. Understanding of the reaction process

A catalyst‐free polysiloxane synthetic process that uses high temperature and pressure water for the hydrolysis and subsequent polycondensation of phenyltrimethoxysilane was studied in detail to gain insights into the reaction mechanism. It was suggested that this process is essentially composed of two stages: (1) oligomerization of phenyltrimethoxysilane yielding low‐molecular weight species with high contents of silanol and methoxy groups and (2) polycondensation of the oligomers yielding high‐molecular weight species. The use of a preformed oligosiloxane as a starting material was informative to understand the polycondensation stage. A modified synthetic process in which a stop valve was introduced to control the internal pressure was developed based on the understanding of the present process. This modified process enabled a two‐stage reaction resulting in a discernible increase of the molecular weight of polysiloxane. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2656–2663, 2009     

Evaluation of an ODS column modified with zwitterionic/nonionic mixed surfactants and its application to direct injection determination of inorganic anions.

An octadecylsilica (ODS) column modified with zwitterionic/nonionic mixed surfactants was evaluated for the direct injection determination of inorganic anions in biological fluids by ion chromatography. A zwitterionic surfactant (sulfobetaine-type) and a nonionic surfactant (polyoxyethylene-type) were used for a stationary-phase modification. When aqueous electrolyte solutions with concentrations of sub-mM to several mM were used as a mobile phase, the zwitterionic surfactant coated on the ODS surface exhibited unique separation selectivity for ionic species, while the nonionic surfactant coated on the ODS might have formed a hydrophilic network over the ODS surface and restricted matrix proteins from adsorbing on the stationary phase. Consequently, the mixed surfactant-modified column system allowed an efficient ion chromatographic separation of inorganic anions as well as a size-exclusive removal of column-fouling proteins. This separation system was applied to the direct injection determination of UV-absorbing anions in human saliva. The detection limits for nitrite, nitrate, iodide and thiocyanate were 3.1, 2.7, 4.5 and 25 microM, respectively, with UV detection at 210 nm (injection volume; 20 microl), and their relative standard deviations for 5 replicate measurements of saliva samples spiked with 100 microM each of those anions were 1.4, 0.9, 2.2 and 5.5%, respectively.