Recent interest in the use of sub- and supercritical water as alternative media for various organic reactions lies in the enhanced solubility and reaction rate of organic substrates, and the increase in the dissociation of water into H₃O⁺ and OH⁻ under these conditions. If properly chosen, organic reactions could take place under homogeneous conditions with no other additives at high temperature and yet the reaction products separate out of the aqueous phase when cooled to ambient conditions, thereby reducing the environmental burden of the workup processes. After short surveys of the preceding studies, we report in this comprehensive paper on our recent collaborative work directed toward the mechanistic and exploratory investigations of organic reactions in sub- and supercritical water in the absence of any added catalyst. They cover the formations of polyacenequinones via crossed aldol condensation of 1,4-cyclohexanediones with arene-o-dicarboxyaldehydes, 1,3,5-triaroylbenzenes by means of Michael-type cyclotrimerization of 1-aryl-2-propyn-1-ones, and 1,3,5-triacetylbenzenes by cyclotrimerization of 4-methoxy-3-buten-2-one, all leading to important intermediates for synthesizing materials of nanotechnological importance. Some experimental and recommended methods and future directions are discussed.

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In this study, in order to use evaluation equation of cracked concrete built by experiments of the author in established structures appropriately, we have applied chloride penetration area to the concrete area in the evaluation equation and demonstrated the area by submergence test. Furthermore, we have studied its application effect by the numerical analysis of the diffusion coefficient considering cracking effect that has been applied its chloride penetration area.

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