Published papers

© 2018 by Japan Oil Chemists’ Society. Cryogenic treatment, like the freeze–thaw process, has been reported to be effective in modifying the physicochemical properties of polymeric hydrogels. However, not much attention has been paid to this process in terms of the precipitation of surfactant–water systems. In this study, two effective cryogenic methodologies were successfully reported to alter the physicochemical properties of a precipitate of an octyl β-D-galactoside (Oct-Gal)–water system. First, hyperrapid cooling (i.e., cooling at 30℃/min) was found to be an effective type of cryogenic treatment: the phase transition temperature (T K ) and enthalpy at the phase transition (ΔH K ) between the crystal-dispersed phase and the sol (micelle) phase significantly decreased. In addition, cryogenic treatment in the presence of electrolytes, such as NaCl, NaBr, and CsCl, was effective even in the absence of the hyperrapid cooling condition. The hyperrapid cooling or the addition of certain electrolytes was considered to prevent the precipitation of the Oct-Gal hemihydrate crystals prior to the complete freezing of ice and the electrolyte/ice eutectic. Hence, the size of the aggregated crystals prepared by the above-mentioned effective cryogenic treatments seemed to be decreased compared with that of the normal precipitated crystals, thereby changing T K and ΔH K . Thus, two basic methodologies for the modification of the physicochemical properties of the crystal-dispersed phase of surfactant–water systems are discussed.

© 2018 American Chemical Society. Micrometer-sized self-propelled oil droplets under a far-from-equilibrium condition have drawn much attention because of their potential as a dynamic model for the chemical machinery in living organisms. To clarify the effect of interactions between the system components (surfactant, oil, and water) on the locomotion mode of droplets, we investigated the behaviors of oil droplets composed of n-heptyloxybenzaldehyde (HBA) in solutions of cationic surfactants having or not having an ester or an ether linkage. It was observed that in solutions of cationic surfactants having an ester or an ether linkage, spherical HBA droplets self-propelled by changing their direction frequently. On the other hand, when this functional group is absent, a slow self-propelled motion of the oil droplets concurrent with the evolution of aggregates on their surface was observed. From the results of measurement of interfacial tension and assessment of self-emulsification, we determined that the attractive interactions of cationic surfactants without an ester or an ether linkage with HBA are stronger than those having the linkage. The difference in the locomotion mode of oil droplets is probably explained from the viewpoint of the interactions among the system components.

キラル自動触媒系が機能する反応システムにおいては，反応初期の統計学的偏差による両異性体量の差が増幅され，自発的に一方の異性体が優先的に生成されてくる可能性が有る。二次核生成により自己複製が可能で，さらに自身の構成要素である鏡像異性体分子を認識出来るキラル結晶が反応系に生成してくるために，自発的に一方の異性体が高選択的に生成する自動触媒的キラル対称の破れの現象について総説した。（６頁）

ビニルフェノールとエタンチオール及びエタンジチオールとのマイケル付加反応及びラジカル付加反応により，フェノール性水酸基とスルフィド基の両方を有する誘導体を合成し，ともに優れた抗菌性を示すことを報告した。またマイケル付加体については，ラードに対して非常に優れた抗酸化性を示すことを紹介した。

キラリティーを有する母結晶からの二次核生成により生成する子結晶は，母結晶と同じキラリティーを有する。反応系内において生成物の結晶化が進行し，さらにその結晶化がキラル自動触媒的二次核生成による進行するために，反応初期の統計学的偏差による両異性体量の差が増幅されて，自発的に一方の異性体が優先的に生成されてくる例を幅広く総説した。（１０頁）

正八面体ビスエチレンジアミン型コバルト錯体の合成反応において観察されるキラル自動触媒過程は、その生成物の過飽和度がある閾値を越えた時点で機能するようになることを見出した。高過飽和度溶液中において形成されたクラスターが、キラル自動触媒種として機能したという仮定に基づいたシミュレーションの結果は、実験的に観察された自動触媒反応速度と過飽和度の関係に一致した。