Masaki Okada

Mechanistic and exploratory investigations into the synthesis of 1,3,5-triaroylbenzenes from 1-aryl-2-propyn-1-ones and 1,3,5-triacetylbenzene from 4-methoxy-3-buten-2-one by cyclotrimerization in hot water in the absence of added acid or base.

Neat 1-phenyl- and 1-(p-tolyl)-2-propyn-1-ones (1 and 1, respectively) were heated in water without any additive at 150 °C for 2 h to give 1,3,5-tribenzoyl- and 1,3,5-tri-(p-toluoyl)benzenes (2 and 2, respectively) in 74 and 52% yields, respectively. The crossed reactions of 1 with the enolate of p-toluoylacetaldehyde (3) and 1 with the enolate of benzoylacetaldehyde (3) were carried out to give unsymmetrically substituted 1-toluoyl-3,5-dibenzoylbenzene (Ph2Tol) and 1,3-ditoluoyl-5-benzoylbenzene (PhTol2), respectively, corroborating the previously proposed reaction mechanism in which 3 and 3 that are formed by rate-determining nucleophilic attack of HO(-) on 1 and 1 or its conjugate acids formed by subsequent protonation would serve as a common intermediate for the formation of 2, 2 and the acetophenone derivatives as byproducts. When 4-methoxy-3-buten-2-one (4) was heated in hot pure water without any additive at 150 °C for 30 min, 1,3,5-triacetylbenzene (5) was obtained in an isolated yield of 77% just by removing water by filtering the crystalline product from the cooled reaction mixture. The reaction did not take place in the absence of water. Slow decompositions of 5 in water set in at the temperature of 300 °C for 30 min.

One‐Pot Synthesis of 1,3,5‐Tribenzoylbenzenes by Three Consecutive Michael Addition Reactions of 1‐Phenyl‐2‐propyn‐1‐ones in Pressurized Hot Water in the Absence of Added Catalysts

Cyclotrimerization of 1-phenyl-2-propyn-1-one in pressurized hot water gave 1,3,5-tribenzoylbenzene in one pot in 65u2009% yield after 7u2005min at 200u2009°C, or in 74u2009% yield after 60u2005min at 150u2009°C. The reaction did not take place in the absence of water, and added base promoted the reaction at 250u2009°C, suggesting a mechanism of three-consecutive Michael addition reactions. The reaction rates increased with temperature, but the yield of 1,3,5-tribenzoylbenzene decreased at the expense of formation of acetophenone as a side product at higher temperatures. p-Methyl and p-chloro-substituents on the phenyl ring retarded and enhanced the reaction, respectively. A mechanism involving the enol of benzoylacetaldehyde at a branching point of the pathway leading to 1,3,5-tribenzoylbenzene and acetophenone was suggested.

Effect of Sound Wave Irradiation on Methane Conversion in DC Pulse Discharge Plasma

The effects of sound wave irradiation were investigated on the efficiency of chemical reaction and product distribution in plasma field generated by DC pulse discharge. Since the discharge plasma provides high energy locally, various chemical reactions ungoverned by thermodynamics can occur. However, the discharge space is extremely confined, which restricts the conversion of feed gas. In this work, the combination of discharge plasma and sound wave irradiation, which increases the vibration motion of the medium particle, was studied. An expansion of streamer into a fan-shape was observed with the irradiation of sound wave. The expansion of the discharge space was positively correlated with the vibration speed of the medium particle (Vs). Accordingly, the effects of sound wave irradiation on the methane conversion (XCH4) were evaluated. When methane diluted in argon (mole fraction of methane was 0.1) was used as the feed gas, methane conversion increased with Vs, and XCH4 at 3.0 m/s of Vs increased to approximately twice that for no sound wave irradiation. This increase in XCH4 resulted from the improvement in the reaction probability due to expansion of the discharge field and change of discharge properties. On the other hand, hydrogen formation and oily and deposit compounds formation were slightly increased. Therefore the enhancement of reaction efficiency and the possibility of product-control of plasma reaction by sound wave combined process were suggested.

Study on Reaction of Coals and Chromic Anhydride. The Estimation by IR Spectrum.

In aqueous solution, Nakayama coal reacts easily with chromic anhydride (CrO3). In comparison with the raw coal, the 1, 100-1, 300cm-1 IR band of CrO3 pretreated coal is remarkably diminished. The intensity change arises from the interaction with chromic anhydride and hydroxyl groups in the coal. The magnitude of the decrease correlates well with the amount of reacted chromic anhydride. From a comparison of the IR spectra of products obtained from the reaction of several model compounds with chromic anhydride, the behavior of 1, 100-1, 300cm-1 IR band was assigned to a change in the C-O stretching vibration in the phenolic hydroxyl groups present in the coal. The method may be applicable as a general method for the determination of phenolic hydroxy groups in coals.