Masakazu Iwasaki

Plasma induced degradation of chlorophenols in an aqueous solution

The reactions of organic compounds in water induced by the plasma which was generated in a localized zone between an electrolytic solution and an anode were investigated. Each of three isomeric monochlorophenols, employed as models of pollutants, underwent the dechlorination followed by oxidative degradation and eventually decomposed to inorganic carbon. It was also clarified that the chlorine atom could be liberated as chloride ion. On the basis of the detailed analysis of the intermediate products and kinetical consideration, was proposed the reaction pathway, where the successive attack of hydroxyl radicals on the benzene rings of starting materials was presumed to be key steps, especially in the initial stage of overall reactions.

Plasma-induced degradation of aniline in aqueous solution

The liquid-phase oxidation induced by a gaseous plasma was investigated. The plasma was generated between an electrolytic solution and a tip of anode in contact with the surface of solution by means of contact glow discharge electrolysis (CGDE). Aniline dissolved in a neutral phosphate buffer solution was smoothly oxidized and eventually degraded to inorganic carbon. As the intermediate products, three isomeric aminophenols, of which p-isomer was predominant, were detected as well as some carboxylic acids such as oxalic, formic and malonic acids. It turned out that the decay of not only aniline but also total organic carbon (TOC) obeyed the first-order rate law. Furthermore, the effects of volume of solution and electrolytic current on the reaction rate were discussed in connection with the reaction mechanism and it was proposed that the hydroxyl radical might be the most likely oxidant responsible for the degradation of aniline.

Synthesis of benzofurans and benzothiophenes by palladium catalyzed cyclocarbonylation of 3-furylallyl and 3-thienylallyl acetates☆

Abstract Acetoxybenzofurans and acetoxybenzothiophenes were obtained in good yields by palladium catalyzed cyclocarbonylation of 3-furylallyl and 3-thienylallyl acetates, respectively.

Aromatic cyanation in contact glow discharge electrolysis of acetonitrile

Contact glow discharge electrolysis of acetonitrile solution containing a variety of aromatic compounds was carried out. A stable discharge was sustained around a platinum wire anode in contact with a surface of solution, when a d.c. high voltage over 500 V was applied between the anode and cathode immersed in the solution under ambient pressure of argon. An aromatic substitution involving radicals produced through the homolytic dissociation of acetonitrile significantly occurred to result in the formation of corresponding cyanoaromatics as well as propionitrile, succinonitrile, and acrylonitrile. The effects of reaction conditions on the current yields of products were discussed in association with the reaction mechanism.

Palladium catalyzed cyclocarbonylation of 3,3-diarylallyl acetates

Abstract Palladium-catalyzed cyclocarbonylation of 3,3-diarylallyl acetates afforded 4-aryl-substituted 1-naphthyl acetates where the cyclization occurred selectively on the more electron-rich ring.

Novel synthesis of phenol derivatives by palladium-catalysed cyclocarbonylation of penta-2,4-dienyl acetates

Palladium-catalysed Cyclocarbonylation of penta-2,4-dienyl acetates in the presence of NEt3 and Ac2O selectively gives phenyl acetates in good yields.

Synthesis and reactivities of a bis(cyanamido)-capped triruthenium complex

The tetraruthenium complex [Cp*RuCl]4 (Cp* = eta(5)-C(5)Me(5)) reacts with Na(2)NCN to afford the anionic bis(cyanamido)-capped triruthenium complex [(Cp*Ru)3(micro(3)-NCN)(2)]- ((2-)), which undergoes single electron oxidation to form [(Cp*Ru)3(micro(3)-NCN)2] upon workup with 1 equiv. of [Cp(2)Fe](PF(6)) (Cp = eta(5)-C(5)H(5)). Treatment of (2-) with 1 equiv. of HCl at room temperature leads to the protonation of one of the Ru-Ru edges to give the hydrido-bridged complex [(Cp*Ru)3(micro-H)(micro-NCN)2], while the cationic side-on NCNH(2) complex [(Cp*Ru)3(micro-Cl)(micro(3)-NCN)(micro(3)-NCNH(2)-1kappaC,N:2kappaC:3kappaN)]Cl (5) is obtained by the reaction of (2-) with an excess amount of HCl at -78 degrees C. On the other hand, the reaction of (2-) with BR(3) (R = Et, Ph) results in the ligation of two BR(3) molecules to the terminal nitrogen atoms of the cyanamido ligands to yield the bis(borane) adduct (PPN)[(Cp*Ru)(3){(micro(4)-NCN)(BR(3))}(2)] (6, PPN = Ph(3)PNPPPh(3)). 6b (R = Et) slowly liberates one BEt(3) molecule in acetone to give the mono(borane) adduct (PPN)[(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(BEt(3))}] (7). (2-) is also shown to react with [AuCl(PPh(3))] or PhCOCl to afford the tetranuclear heterometallic complex [(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(AuPPh(3))}] (8) or the benzoylcyanamido complex [(Cp*Ru)3(micro(3)-NCN)(micro(3)-NCNCOPh)] in which the Au(PPh(3))+ or benzoyl fragment is bound to the terminal nitrogen atom of a cyanamido ligand. The molecular structures of PPN+(2-), 5.C(6)H(6), 7 and 8.C(6)H(6) have been determined by single-crystal X-ray analyses.

Syntheses, structures and solution behaviour of cyclotriphosphato complexes of Pd(II), Pt(II) and Pt(IV)

The cyclotriphosphate ion (P3O93−) as a PPN [PPN = (Ph3P)2N+] salt reacted in CH2Cl2 at room temperature with the cationic solvated complexes of Pd(II) and Pt(II), [M(phosphine)2(Me2CO)2]2+ [M = Pd, Pt; phosphine = PPh3, PMePh2, 1/2 Ph2P(CH2)2PPh2 (dppe), 1/2 Ph2P(CH2)4PPh2 (dppb)], to give the anionic P3O9 complexes (PPN)[Pd(P3O9)(PPh3)2] (1), (PPN)[Pd(P3O9)(PMePh2)2] (2), (PPN)[Pt(P3O9)(PPh3)2] (3), (PPN)[Pt(P3O9)(PMePh2)2] (4), (PPN)[Pt(P3O9)(dppe)] (5) and (PPN)[Pt(P3O9)(dppb)] (6). Crystallographic studies revealed that the P3O9 ligand in complexes 1–4 and 6 adopts a normal chair conformation and behaves as a pseudo-tridentate ligand with two normal M–O bonds and an additional weak M⋯O interaction. In 1 and 3, the terminal P3O9 oxygen atom weakly bound to the metal centre forms relatively strong intramolecular CH⋯O hydrogen bonds with the phosphine ligands. In contrast, the P3O9 ligand in 5 is bidentate and takes a pseudo-boat conformation. Complexes 1–6 are fluxional in solution and exhibit only one singlet due to the P3O9 ligand in the 31P–{1H} NMR spectra at room temperature; the signals of complexes 4–6 split into two at −40 to −70 °C. The activation parameters for the fluxional behaviour of 6 were determined by the line shape analysis of the variable temperature 31P–{1H} NMR spectra. The Pt(IV) complex (PPN)2[PtMe3(P3O9)] (7) was also synthesised and structurally characterised.

Novel ketene formation by reactions of acid chlorides with low-valent platinum complexes

Abstract Pt(CO)in n (PPh 3 ) 4- n ( n = 012-2) reacts with Ph 2 CHCOCl under CO to afford diphenylketene and trans -PtHCl(PPh 3 ) 2 . For this reaction, the rate law is zero order in the platinum complex, first order in Ph 2 CHCOCl, and first order in free PPh 3 . A primary isotope effect ( k H / k D = 4.5) was observed in the reaction of Ph 2 CDCOCl. A mechanism is proposed which involves the rate-determining enolization of Ph 2 CHCOCl by PPh 3 followed by fast abstraction of HCl by a plantinum(0) complex.