熱測定
Online ISSN : 1884-1899
Print ISSN : 0386-2615
ISSN-L : 0386-2615
最新号
選択された号の論文の8件中1~8を表示しています
巻頭言
特集「溶液の熱力学の新潮流」にあたって
  • 神崎 亮
    2024 年 51 巻 1 号 p. 2
    発行日: 2024/01/25
    公開日: 2024/02/27
    ジャーナル 認証あり
  • 城田 秀明, マハルーフ コヤカット, 矢嶋 慎吾, 佐藤 純平, 森山 克彦
    2024 年 51 巻 1 号 p. 3-9
    発行日: 2024/01/25
    公開日: 2024/02/27
    ジャーナル 認証あり
    Deep eutectic solvents (DESs) are liquid-state mixtures, which mostly consist of two or more solid compounds, at room temperature because of the strong eutectic effect. After discovering a liquid-state mixture of choline chloride and urea (1:2 in molar ratio) at room temperature as DES in 2003, DESs have gotten more attention recently as a new type of solvent. In this review, we introduce unique DESs consisting of an organic iodide salt, e.g., 1-alkyl-3-methylimidazolium iodides and ammonium iodides, and iodine. The DESs of an organic iodide salt and iodine are easily prepared: just mixing two components. They show a very high electrical conductivity, typically more than 10 mS cm–1. For example, a 1:2.5 mixture of methylammonium iodide and iodine shows approximately 100 mS cm–1 at 298 K. Based on the viscosity and Raman spectrum, the superior electrical conductivity of the DESs is attributed to the Grotthuss mechanism. In this article, we also introduce our attempt for differential calorimetry measurements of the DESs, which possess corrosivity for a wide variety of metals, using a fluororesin-coated aluminum pan.
  • 梅木 辰也
    2024 年 51 巻 1 号 p. 10-14
    発行日: 2024/01/25
    公開日: 2024/02/27
    ジャーナル 認証あり
    Guanidinium cation and urea are often used as protein denaturants because of their strong hydrogen-bond ability. A deep eutectic solvent (DES) composed of guanidine hydrochloride (GuHCl, Tm = 458 K) and urea (U, Tm = 407 K) with a molar ratio of [U]/[GuHCl] = 2 is a liquid medium that has the potential to denature proteins and dissolve biomaterials. However, heating is essential when using 2U-GuHCl as a liquid solvent. This is because the eutectic temperature of this DES is 331 K, which is higher than room temperature. This heating is a serious problem when dissolving solutes with low thermal stability. We focused on two urea derivatives, N-methylurea (Um, Tm = 378 K) and N-hydroxyurea (Uh, Tm = 414 K), to obtain GuHCl-based DESs in liquid state at room temperature. Since all of the GuHCl-based DESs containing Um molecules were fluid at room temperature, the Um molecule is a candidate hydrogen bond donor for fluidizing GuHCl-based DESs. This paper presents experimental results of binary and ternary DESs composed of GuHCl, U, Um, and Uh. In addition, preparation methods for general DESs are outlined.
  • 渡辺 日香里, 韓 智海, 梅林 泰宏
    2024 年 51 巻 1 号 p. 15-21
    発行日: 2024/01/25
    公開日: 2024/02/27
    ジャーナル 認証あり
    Ionic liquids are composed only of ionic species and have been attracted attention as electrolytes for fuel cells and next-generation secondary batteries. Ionic liquids are often found to have the specific ionic conduction mechanism. We recently found that the equimolar mixtures of N-methylimidazole (C1Im) and acetic acid (CH3COOH) have significant ionic conductivity, although only electrically neutral molecules practically exist in their equimolar mixture. We propose such liquids can be called as the pseudo-protic ionic liquids pPILs and consider that the specific proton conduction without static acid dissociation may occur in the mixture. On the other hand, solvate ionic liquids have been proposed as electrolyte solution for lithium sulfur battery. In this study, we discuss on ionic conduction mechanism for the nonequimolar pPILs. In addition, we demonstrate in-situ impedance measurements to reveal ion dynamics in electrode/electrolyte interface for the battery using the solvate ionic liquid.
  • 金崎 悠
    2024 年 51 巻 1 号 p. 22-26
    発行日: 2024/01/25
    公開日: 2024/02/27
    ジャーナル 認証あり
    Hydrophobic dyes are used in water with solubilizers. Hydrotrope is a solubilizer of low molecular weight, weakly amphiphilic organics. and is known to promote solubilization of drugs, dyes, and pigments. One of most famous hydrotropes, urea, serves as an efficient solubilizing agent for dyes. In this study, in order to elucidate the molecularlevel mechanisms responsible for urea's effectiveness as a solubilizer, we apply a statistical thermodynamics approach rooted in the Kirkwood-Buff theory of solutions. Our findings demonstrate two key insights: (i) in contrast to the traditional notion of " water structure disruption, " the impact of urea on dye hydration has a relatively minor role in the solubilization process; (ii) the primary driving force for solubilization arises from the accumulation of urea molecules surrounding hydrophobic dye molecules.
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