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Reactions in Water Involving the “On‐Water” Mechanism
Author(s) -
Kitanosono Taku,
Kobayashi Shū
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201905482
Subject(s) - catalysis , mechanism (biology) , layer (electronics) , reaction mechanism , chemistry , chemical reaction , water chemistry , chemical engineering , environmental science , environmental chemistry , organic chemistry , engineering , epistemology , philosophy
Ever‐evolving catalyst advances in synthetic protocols using water as a reaction medium have enriched the understanding of sustainable organic chemistry. Because conventional classification and definitions were ambivalent, it is proposed here that catalytic reactions using water be collectively called to be “in water”, with further classification into seven types. When accelerated in water as heterogeneous mixtures, the reactions can be regarded as following an “on‐water” mechanism. The original term “on water” coined by Sharpless is incongruous with catalytic reactions, whereas on‐water used in this review covers all the interfaces involving water where chemical reactions are accelerated. As a result of the unconcluded dispute on the antiquated catalyst‐free “on water” model, the modified model defines three water layers: water molecules that are oriented to extrude protons toward the oil phase in the inner layer, those enwrapped by a secondary layer, and finally the bulk water layer. In light of the latitudinous outlook on the role of water at the interface, selected examples of reactions, in particular those reported over the past decade, that follow an “on‐water” mechanism are reviewed herein.