Showing papers by "Akihiro Wakisaka published in 1998"
TL;DR: The microscopic structure observed through the mass-spectrometric analysis of clusters isolated from solution also shows good contrast between these binary mixtures as follows: methanol molecules have substitutional interaction with water clusters, while acetonitrile molecules have additional interaction with the water clusters as discussed by the authors.
Abstract: Water–methanol and water–acetonitrile, which show exothermic and endothermic mixing, respectively, represent good contrast in non-ideality of a binary mixture. The microscopic structure observed through the mass-spectrometric analysis of clusters isolated from solution also shows good contrast between these binary mixtures as follows: (1) methanol molecules have substitutional interaction with water clusters, while acetonitrile molecules have additional interaction with water clusters; (2) the clustering of methanol molecules are promoted in the presence of water; on the contrary, the acetonitrile clusters are disintegrated in the presence of water. Such findings could partially explain the non-ideality of these binary mixtures on the basis of the cluster structures.
140 citations
TL;DR: In this article, the solvent effect on acid-base interaction between acetic acid and pyridine has been studied by the mass spectrometric analysis of clusters isolated from liquid droplets.
Abstract: The solvent effect on the acid–base interaction between acetic acid and pyridine has been studied by the mass spectrometric analysis of clusters isolated from liquid droplets. The clusters resulting from the acetic acid–pyridine, acid–base, interaction in water are quite different from those in acetonitrile solvent. In water (acetic acid∶pyridine∶water = 1∶1∶10) the acid–base interaction occurs through the intercluster interaction between acetic acid and pyridine clusters. On the other hand, in acetonitrile (acetic acid∶pyridine∶acetonitrile = 1∶1∶10), the acid–base interaction proceeds through an intermonomer interaction between an acetic acid molecule and pyridine molecule, and the clusters are produced through the aggregation of a polar (acetic acid)δ–(pyridine)δ+ complex. This solvent effect is mainly attributed to the cluster structure of acetic acid and pyridine in water and acetonitrile solvent.
16 citations
TL;DR: In this paper, the acid-base interactions were investigated by mass spectrometry of clusters isolated from solutions containing a carboxylic acid (propionic, butyric or hexanoic acid), an aromatic base (pyridine or pyrazine) and a solvent (water, acetonitrile or propionitrile).
Abstract: Acid–base interactions were investigated by mass spectrometry of clusters isolated from solutions containing a carboxylic acid (propionic, butyric or hexanoic acid), an aromatic base (pyridine or pyrazine) and a solvent (water, acetonitrile or propionitrile). In water, self-aggregation of the carboxylic acid molecules due to hydrophobic interaction to form carboxylic acid clusters, such as (butyric acid)n, was prominent, and acid–base interaction proceeded between the carboxylic acid clusters and the basic molecules. In acetonitrile, the acid–base interaction was sensitive to the relative strength of the base. When pyridine (relatively strong base) was used as a base, clustering proceeded through the formation of a polarized acid–base complex, (acid)δ-(base)δ+. However, when pyrazine (relatively weak base) was used as a base, self-aggregation of the acid molecules became favorable. In propionitrile, such clusters were not observed because each molecule was separated by individual solvation. This solvent effect is related to the solvation structure, which determines the balance between the self-aggregation of the acid molecules and the formation of the polarized acid–base complex. It has also been demonstrated that the balance of the above intermolecular interactions is also dependent on the size of the alkyl group of the carboxylic acid. The results of the mass spectrometry partially show the microscopic view for the effect of solvent, pKa and the size of the alkyl group on the acid–base interaction in solution.
15 citations
01 Jan 1998
TL;DR: The microscopic structure observed through the mass-spectrometric analysis of clusters isolated from solution also shows good contrast between these binary mixtures as follows as discussed by the authors : methanol molecules have substitutional interaction with water clusters, while acetonitrile molecules have additional interaction with the water clusters.
Abstract: WaterEmethanol and waterEacetonitrile, which show exothermic and endothermic mixing, respectively, represent good contrast in non-ideality of a binary mixture. The microscopic structure observed through the mass-spectrometric analysis of clusters isolated from solution also shows good contrast between these binary mixtures as follows : (1) methanol molecules have substitutional interaction with water clusters, while acetonitrile molecules have additional interaction with water clusters ; (2) the clustering of methanol molecules are promoted in the presence of water ; on the contrary, the acetonitrile clusters are disintegrated in the presence of water. Such Ðndings could partially explain the non-ideality of these binary mixtures on the basis of the cluster
14 citations