bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparations and Characterization of Cyclopalladated Complexes of 1-Ethyl-2-phenylimidazole
Authors: Hiraki Katsuma , Fuchita Yoshio , Nakaya Hiroshi , Takakura Shinji 
Published: July 2006

Abstract
Reactions of 1-ethyl-2-phenylimidazole (Hepim) with lithium tetrachloropalladate(II) and palladium(II) acetate give dichlorobis (1-ethyl-2-phenylimidazole, 3-N) palladium (II) and a new cyclopalladated binuclear complex, di-μ-acetato-bis[2-(1′-ethyl-2′-imidazolyl)phenyl, 1-C, 3′-N]dipalladium(II), respectively. The latter complex is readily converted by a metathetical reaction with sodium chloride into a chloro-bridged analogue, [{PdCl(epim)}2]. The chloro-bridged complex reacts with 4-picoline, tertiary phosphines, thallium(I) acetylacetonate, sodium diethyldithiocarbamate, and 2,2′-bipyridyl to give the corresponding mononuclear cyclopalladated complexes. All the complexes prepared in this study are characterized by means of IR, 1H-NMR, and mass spectroscopies.
Preparation and Properties of “β1 and β2”-Isomers of the Salicylato(triethylenetetramine)cobalt(III) Complex
Authors: Yamamoto Yoshihisa , Toyota Eiko 
Published: July 2006

Abstract
β-Salicylato(triethylenetetramine)cobalt(III) chloride monohydrate has been obtained from salicylic acid and β-dichloro(triethylenetetramine)cobalt(III) chloride at pH 10–11. The separation of “β1 and β2” isomers was attempted by using ion exchange. The IR spectra of the “β1 and β2” complexes showed four strong absorption peaks in the 990–1100 cm−1 region. This indicates that the complexes assume the β-form. The 1H-NMR spectrum of ammine protons of coordinated triethylenetetramine of the β1 complex showed six signals with an intensity ratio of 1:1:1:1:1:1, while that of the β2 complex showed five signals with an intensity ratio of 1:1:1:1:2, in 1.8 mol dm−3 D2SO4. The order of the chemical shifts in ppm is N(2)H&lt;N(3)H&lt;N(4)H2&lt;N(1)H2. Thus, the protons of the secondary N(3)H of coordinated triethylenetetramine absorb at lower fields than the terminal N(1)H2 protons. The 13C-NMR spectra of the “β1 and β2” complexes in heavy water showed six signals for trienligand carbons and seven signals for salicylato-ligand carbons. The spectra of these complexes have shown two different configurations of the “β1 and β2” complexes.
α-Chlorination of Long-chain Aliphatic Acids
Authors: Ogata Yoshiro , Sugimoto Toshiyuki , Inaishi Morio 
Published: July 2006

Abstract
Chlorination of long-chain aliphatic acids with a Cl2–O2 mixture in the presence of chlorosulfuric acid at 85 °C gave the corresponding α-chloro acids in good yields (ca. 90%) along with a little amount of aliphatic α-sulfo acids, but no α,α-dichloro acids.
Spectrophotometric Determination of Copper Separated by Means of Adsorption of Its Pyrrolidinedithiocarbamate on Naphthalene
Authors: Fujinaga Taitiro , Takagi Yasuhiro , Satake Masatada 
Published: July 2006

Abstract
The copper chelate of APDC was adsorbed on microcrystalline naphthalene to determine trace amounts of copper. The optimum pH range for the adsorption is 1.5–10.5. The chelate in dimethylformamide has an absorption maximum at 435 nm. Beer’s law holds in the range 2.5–48 μg of copper in 10 ml of dimethylformamide. The molar absorptivity is 1.3×104l·mol−1·cm−1 and the sandell sensitivity 4.8×10−3μg of copper per cm2. Other factors such as amounts of reagent and naphthalene, shaking time, standing time and diverse ions were studied. The method can be applied to the determination of copper in Bovine Liver and human hair.
Ylide-Metal Complexes. III. Preparation and Properties of Gold(I) Complexes of Alkylidenetriphenylphosphoranes and -arsoranes
Authors: Yamamoto Yoshihisa , Kanda Zenjiro 
Published: July 2006

Abstract
Ylide-gold complexes of the type triphenylphosphine(triphenylphosphonium alkylide)gold(I) chloride, (Remark: Graphics omitted.), and bis(triphenylphosphonium alkylide)gold(I) chloride, (Remark: Graphics omitted.), have been obtained from alkylidene triphenylphosphoranes, Ph3P=CH–R (R: H, CH3, CH(CH3)2), and (triphenylphosphine)gold(I) chloride, Ph3PAuCl. Bis(triphenylarsonium methylide)gold(I) chloride, [Ph3AsCH2–Au–CH2AsPh3]Cl, has been synthesized from methylenetriphenylarsorane and Ph3PAuCl. In these organogold complexes, the ylides are attached to the gold atom through the carbanionic donor atom. The 1H-NMR spectra of [Ph3PCH2–Au–PPh3]Cl indicates an intermolecular exchange process in the temperature range +25–−50 °C.
The Extraction of the Chromium(III) Ion from Trichloroacetate Solutions to Inert Solvents Containing Trioctylphosphine Oxide
Authors: Imura Hisanori , Kiba Toshiyasu , Honjo Takaharu 
Published: July 2006

Abstract
Chromium(III) has been extracted with 0.1 mol dm−3 trioctylphosphine oxide(TOPO) in various inert solvents from a 0.1 mol dm−3 trichloroacetate(TCA−) buffer solution of pH 3.5 to 6.0. As diluents of TOPO, hexane and cyclohexane are most effective, while chloroform is quite ineffective. The extraction mechanism has been clarified by analyzing separately the distribution of water, trichloroacetic acid(HTCA), and the Cr(III) ion between the aqueous and organic phases. Water and HTCA are present in the cyclohexane phase as H2O·TOPO and HTCA·TOPO respectively. Chromium(III) is extracted with TOPO into cyclohexane as an ionassociation complex like Cr(H2O)63+(TCA−)3·3TOPO, and the extraction constant is 107.68. It is concluded that the hexahydrated Cr(III) ion is solvated by three molecules of TOPO, forming an ion pair with three trichloroacetate anions. The extractability of Cr(III) in the present system depends most effectively on the concentration of HTCA-free TOPO in the organic phase.
ESR Study of 63Cu(II) Doped in Single Crystals of Bis(alkyl 3-alkylidenedithiocarbazato)nickel(II) and -zinc(II). II. Proton Hyperfine Structure and Tetrahedral Distortion
Authors: Oniki Takayuki 
Published: July 2006

Abstract
The ESR spectra of 63Cu(II) diluted in several single crystals of the title Ni(II) and Zn(II) complexes are reported. In the substituted benzylidene groups, hyperfine structure(hfs) due to the magnetically equivalent two protons have been observed. The hfs were resolvable only in a limited magnetic direction due to the small anisotropic coupling constants. The coordination around Cu(II) ion has been found to be cis in all the Zn(II) complexes and the ESR parameters are more anisotropic than in the Ni(II) complexes. The relationship between the tetrahedral distortion and the ESR parameters has been interpreted using the d-orbital coefficients in the ground state.
Coenzyme Models. 18. Metal Catalysis of NADH Model Reduction in Aqueous Systems
Authors: Shinkai Seiji , Hamada Hisatake , Kusano Yumiko , Manabe Osamu 
Published: July 2006

Abstract
Metal ions (Ni2+ and Zn2+) affected the NADH model reduction of 2-pyridinecarbaldehyde and Schiff bases in aqueous systems. In particular, the rate of the dihydroquinoline reduction of N-(2-pyridylmethylene)-2-pyridylmethylamine was augmented by more than 200-fold, compared with that in the absence of metal ions. On the other hand, the reduction of benzil, ethyl benzoylformate, and trifluoroacetophenone was not subject to the metal catalysis. The enhanced reactivity is accounted for by the affinity of Schiff bases toward metal ions. The efficiency of the metal catalysis was compared with that of the proton catalysis. This is the first example of the systematic examination of the metal catalysis in aqueous systems.
Catalytic Asymmetric Hydroformylation by the Use of Rhodiumcomplexes of Chiral Bidentate Phosphorus Ligands Bearing: Saturated Ring Skeletons
Authors: Hayashi Teruyuki , Tanaka Masato , Ikeda Yoshikazu , Ogata Ikuei 
Published: July 2006

Abstract
(1S,2S)-1,2-Bis(diphenylphosphinoxy)cyclohexane, (1S,2S)-1,2-bis(phosphinomethyl)cyclohexanes, (2R,3R)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(phosphino) butanes, and (1R,2R)-1,2-bis(phosphinomethyl) cyclobutanes, whose phosphino groups were diphenylphosphino or 5H-dibenzophosphol-5-yl groups where the rotation of phenyl-P bonds is impossible, were used as chiral ligands in rhodium-catalyzed asymmetric hydroformylation. The highest stereoselectivity was attained by the use of (1R,2R)-1,2-bis(5H-dibenzophosphol-5-ylmethyl)cyclobutane or (2R,3R)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(5H-dibenzophosphol-5-yl)butane.
Nucleophilic Ion Pairs. 8. Facile Nucleophilic Cleavage of Dinitrophenyl Sulfate in the Presence of Micellar Zwitterionic Hydroxamates
Authors: Kunitake Toyoki , Sakamoto Tetsuo 
Published: July 2006

Abstract
The sulfate transfer reaction from dinitrophenyl sulfate to hydroxamate nucleophiles was studied in the presence of several types of aqueous micelles at 30 °C, pH 8–9. The zwitterionic hydroxamate was a nucleophile much better than the anionic hydroxamate in the CTAB micelle. The kinetic behavior of the zwitterionic hydroxamate nucleophile was not straightforward and the reactivity of the nucleophile increased with the increase in the relative concentration of the nucleophile and surfactant. These results in the CTAB micelle was analyzed in terms of the two phase model and the rate enhancement relative to the nonmicellar reaction was attributed to substrate binding in the micellar phase and the micellar activation of the hydroxamate nucleophile. The cleavage of dinitrophenyl sulfate by the micellar zwitterionic nucleophile was faster than that by the nonmicellar hydroxamate and the water cleavage by factors of ca. 104 and more than 107, respectively: the fastest cleavage ever observed at the ambient condition.
Reactions of 2-Hydroxyimino-3-methyl-2,3-dihydrobenzothiazole Derivatives with Grignard Reagents and Organolithiums
Authors: Akiba Kin-ya , Shiraishi Hiroaki , Inamoto Naoki 
Published: July 2006

Abstract
Reactions of 2-hydroxyimino-3-methyl-2,3-dihydrobenzothiazole derivatives (1) with Grignard reagents gave 2-hydroxyimino (1e) and 2-(substituted imino)-3-methyl-2,3-dihydrobenzothiazoles as major products, where 1e was reduced by excess Grignard reagents to 2-imino derivative. On the other hand, reactions of 1 with organolithiums afforded o-(methylamino)phenyl sulfides as a major product.
Functionalization of trans-Decalin. III. A Stereospecific Preparation of Vicinal cis Two Methyl Groups of Eremophilane Skeleton, Leading to dl-Dehydrofukinone
Authors: Torii Sigeru , Inokuchi Tsutomu , Yamafuji Tetsuo 
Published: July 2006

Abstract
A procedure for the preparation of dl-dehydrofukinone (1), an eremophilane type sesquiterpene, from the diene adducts (3), prepared from the reaction of 4-methyl-3-methoxycarbonyl-2-cyclohexen-1-one with butadiene, is described. Acetalization-reduction (LiAlH4) of 3 followed by treatment of the corresponding mesylate with base provided 5,6-cis-5-methyltricyclo[4.4.1.01,6]undec-8-en-2-one (7) in 69% overall yields. Reductive cleavage of 7 with lithium metal afforded trans-4β,4aβ-dimethyl-Δ6,7-octalin-1-one (8), bearing a set of vicinal cis two methyl groups on the C-4 and C-4a carbons in an 83% yield. Functionalization of the double bond of 8 involves (1) reduction of carbonyl group and following tetrahydropyranylation, (2) epoxidation followed by regiospecific reduction of the oxirane ring at the C-6 position, and (3) subsequent oxidation of the hydroxyl group, giving trans-4aβ,5β-dimethyl-8β-tetrahydropyranyloxydecalin-2-one (14b) in good yields. The conversion of 14b into the desired 1 was achieved smoothly by (1) hydrolysis of tetrahydropyranyl ether, (2) pyrolysis of its mesylate, and (3) subsequent aldol reaction with acetone followed with dehydration and isomerization of the double bond.
Synthesis of α-Trialkylsilyl Ketones
Authors: Obayashi Michio , Utimoto Kiitiro , Nozaki Hitosi 
Published: July 2006

Abstract
The isomerization of 2-trimethylsilyl-2,3-dialkyloxiranes occurs in the presence of MgI2 to give α-trimethylsilyl ketones only, if one starts from (2S*,3S*)-isomers. In contrast, however, the reaction of (2S*,3R*)-oxiranes produces enol silyl ethers in addition to α-trimethylsilyl ketones. The reaction proceeds via the Mg salts of regioand stereoselectively produced β-iodo-β-trimethylsilyl alcohols, each diastereomer of which behaves differently. Remarkably, Li salts of both iodohydrins [(2S*,3S*)- and (2S*,3R*)-isomers] give α-trimethylsilyl ketones exclusively. This provides efficient procedures for preparing α-trimethylsilyl ketones from a mixture of diastereomeric silyloxiranes.
Syntheses of Steroidal π-Allyl Palladium Chloride Complexes
Authors: Satoh J Yasuo , Horiuchi C Akira 
Published: July 2006

Abstract
The reaction of the following steroidal olefins with palladium(II) chloride in the presence of potassium acetate in acetic acid afforded the corresponding steroidal π-allyl palladium chloride complexes: 5α-cholest-1-, -2-, and -3-ene; cholest-4- and -5-ene; 3-methyl- and 3-phenyl-5α-cholest-2-ene; 3β-chloro- and 3β-acetoxycholest-5-ene; and 5β-cholest-1-, -2-, and -3-ene.
Enantioface-differentiating (Asymmetric) Hydrogenation of Keto Ester with Modified Nickel Catalyst. XXXII. Structural Requirements of Modifying Reagent and Substrate
Authors: Okamoto Shinji , Harada Tadao , Tai Akira 
Published: July 2006

Abstract
The enantioface-differentiating hydrogenation of α-, β-, γ-, and δ-keto esters over α-, β-, and γ-amino acid–MRNi has been conducted. The optimum enantio-differentiating power of α-amino acid-MRNi has been found in the hydrogenation of the β-keto ester and that of β-amino acid-MRNi found in the hydrogenation of the γ-keto ester. The results have been explained in terms of the intermolecular recognition between substrate and modifying reagent through the functional groups.
The Liquid-phase Oxidation of Hydrocarbons with Molecular Oxygen. II. A Highly Selective Formation of α-Tetralone by the Metal-catalyzed Oxidation of Tetralin in the Presence of N,N-Dialkylamides
Authors: Mizukami Fujio , Horiguchi Yutaka , Tajima Masaki , Imamura Juichi 
Published: July 2006

Abstract
The metal-ion catalyzed oxidation of tetralin was carried out in different solvents in which metal salts tend to be soluble. It was found that, for the production of α-tetralone, a chromium salt is the best catalyst among the first-transition-metal salts employed, while N,N-dialkylamides are the best solvents or the best additives. For example, in the tris(acetylacetonato)chromium(III)-catalyzed oxidation of tetralin in the presence of N,N-dimethylacetamide, α-tetralone was obtained in a 93.0% yield at a 27.2% tetralin conversion. The decomposition of α-tetralyl hydroperoxide (THP) with different first-transition-metal catalysts was also carried out in N,N-dimethylformamide in order to elucidate the formation mechanism for α-tetralone in the oxidation of tetralin in the presence of N,N-dialkylamides. It was concluded that the product distribution in the oxidation mainly depends on the decomposition mechanism of THP, and that N,N-dialkylamides seem to promote the reaction of the α-tetralylperoxyl radical with low valent metal ions, ROO·+Mn+→α-tetralone+OH−+M(n+1)+.
Studies on Inorganic Precipitate Membranes: Membrane Potential and Bi-ionic Potential
Authors: Beg M Nasim , Siddiqi Fasih A , Singh Surendra P , Gupta Veena , Prakash Poorna 
Published: July 2006

Abstract
Electrical potentials arising across barium(II) phosphate, mercury(II) iodide and cobalt(II) chromate membranes using various 1:1 electrolytes are reported. Thermodynamically effective fixed charge density, which is an important parameter governing the membrane phenomena, has been evaluated by the theory of Toyoshima and Nozaki. Using the values of effective fixed charge density determined, the theory of bi-ionic potentials developed by Toyoshima and Nozaki based on the principles of the irreversible thermodynamics has been examined. Theoretical predictions were borne out quite satisfactorily by our experimental results.
Kinetics and Mechanism of Formation of Pentaammine(glycine)rhodium(III) Ion from Pentaammineaquarhodium(III) Ion and Glycine in Weakly Acidic Media
Authors: Chatterjee C , Basak A K 
Published: July 2006

Abstract
The rates of formation of pentaammine(glycine)rhodium(III) ion from pentaammineaquarhodium(III) ion and glycine in weakly acidic media have been studied spectrophotometrically at different glycine and acid concentrations in the temperature range of 60–80 °C. The rate has been found to be insensitive towards the change in ionic strength from μ=0.5 to 2.0 M of the medium. The activation parameters, ΔH\eweq and ΔS\eweq values are 22.2±1.0 kcal mol−1 and −9.2 e.u. respectively. The results are in accord with a mechanism involving a fast 1:1 outer-sphere association between the pentaammineaquarhodium(III) ion and glycine in zwitter ionic form followed by its transformation into the product by a process where the incoming ligand is appreciably bonded to the metal ion in the transition state.
Studies on Uranyl Complexes. II. Unidentate Carboxylate Coordination in Uranyl Complexes of α-, β-, and γ-Amino Acids: A Polarographic Study
Authors: Ramanujam V V , Rengaraj K , Sivasankar B 
Published: July 2006

Abstract
Polarographic investigation of uranyl complexes with potentially bidentate α-, β-, and γ-amino acids have been carried out. The polarographic behaviour of these complexes as a function of pH and ligand concentration has revealed the nature of binding to be unidentate carboxylate coordination in the complexes. The amino group is not involved in coordination. The relative stabilities of α-, β-, and γ-amino acid complexes are discussed.
Isomerism of the Metal Complexes Containing Multidentate Ligands. VIII. Chromatographic Behavior of [CoN6]3+-type Complexes on an SP-Sephadex Column
Authors: Sakakibara Katsumi , Yoshikawa Yuzo , Yamatera Hideo 
Published: July 2006

Abstract
An empirical rule is presented for the elution order of [CoN6]3+-type complexes in chromatography on SP-Sephadex columns. The relative elution rates have been correlated with the number and the kind of the octahedral faces of the complex on which ion association with a phosphate ion occurs.
Preparation of Anhydrous N,N′-Dicyclohexylalloxan and Its Use in Dehydration
Authors: Endo Takeshi , Okawara Makoto 
Published: July 2006

Abstract
Anhydrous N,N′-dicyclohexylalloxan has been prepared and used as a dehydrating agent for carboxylic acids in the esterification of carboxylic acids with alcohols.
Configuration et Conformation en Solution de Quelques α-Hydroxyiminocetones Cycliques
Authors: Bernadou Jean , Bonnafous Monique 
Published: July 2006

Abstract
Les dérivés α-hydroxyiminés des cyclanones en C6 (un isomére), C8 (deux isoméres) et C12 (un isomére) ont tous la configuration anti ; la conformation est variable selon la taille du cycle: s-cis pour le terme en C6, s-cis ou s-trans pour les termes en C8, s-trans pour le terme en C12.
The Relationship of π-Binding Energy with Molecular Connectivity in Hydrocarbons
Authors: Gupta Satya P , Singh Prithvi 
Published: July 2006

Abstract
Hückel’s π-binding energy, Eπ, in hydrocarbons is found to be parallel to Kier’s molecular connectivity index, χ. In either class of hydrocarbons, alternant or non-alternant, the regression analysis reveals a highly significant linear correlation between Eπ and 1χv (the first order valence connectivity index).
The Reaction of Copper(I) Methyltrialkylborates with 1-(1-Pyrrolidinyl)-6-chloro-1-cyclohexene
Authors: Yamada Kinji , Yano Takashi , Miyaura Norio , Suzuki Akira 
Published: July 2006

Abstract
The reaction between copper (I) methyltrialkylborates readily obtainable from organoboranes and 1-(-1-pyrrolidinyl)-6-chloro-1-cyclohexene was found to give corresponding alkylation products which are readily hydrolyzed to alkylated cyclohexanones.
Oxidation of 3,5-Di-t-butylcatechol Catalyzed by Metal Acetylacetonates in Organic Solvents
Authors: Sakamoto Hiroyuki , Funabiki Takuzo , Yoshida Satohiro , Tarama Kimio 
Published: July 2006

Abstract
The oxidation of 3,5-di-t-butylcatechol (3,5-DTBC) has been studied in organic solvents in the presence of metal acetylacetonates (M(acac)2). The catalytic activity of M(acac)2 decreased in the order M=Mn&gt;Co&gt;Ni&gt;&gt;Fe, and the product was 3,5-di-t-butyl-o-benzoquinone (3,5-DTBQ). The kinetic analysis has suggested a mechanism in which the radical chain reactions involving 3,5-di-t-butyl-o-benzosemiquinone (3,5-DTBSQ·) and hydroperoxyl radical (·OOH) are initiated by the reaction of 3,5-DTBC with the initially formed dioxygen metal complexes. Kinetic parameters for the complexation of molecular oxygen by Mn(acac)2 and Co(acac)2 were estimated: ΔH\eweq(kJ mol−1)=4.6±0.8 for Mn, 29.7±0.8 for Co; ΔS\eweq(J mol−1K−1)=−200±2 for Mn, −135±2 for Co.
The Oxidation Activity and Acid-Base Properties of CO3O4–V2O5 and CO3O4–MoO3 Systems
Authors: Ai Mamoru 
Published: July 2006

Abstract
The acidity and basicity of Co3O4–V2O5 and Co3O4–MoO3 systems, with different compositions, were measured by means of the adsorption of NH3, pyridine, and CO2. The values of acidity were also confirmed by studying the catalytic activity for acid-catalyzed reactions, such as the dehydration of isopropyl alcohol and the isomerization of 1-butene. With the addition of V2O5 or MoO3, the basicity rapidly decreases and the acidity gradually increases. The catalytic activity for the oxidation of hexane is well correlated with the basicity of the catalysts. With the Co3O4-rich catalysts, V/(Co+V) or Mo/(Co+Mo)&lt;0.4, butadiene is mainly oxidized to CO2; the rate is also correlated to the basicity. However, the Co3O4-poor catalysts, V/(Co+V) and Mo/(Co+Mo)&gt;0.6, show a good selectivity for the maleic anhydride formation. The Co3O4-containing catalysts, regardless of the composition, are not effective for the selective oxidation of butene to butadiene. In the oxidation of methanol, the Co3O4-rich catalysts give only CO2. However, with the Co3O4-poor catalysts, formaldehyde is almost the sole product. It is concluded that the catalytic behavior is to be interpreted, to a considerable extent, in terms of the acid-base properties of the metal oxides.
Correlation between Electron Capture Response and Chemical Structure for Benzyl Chlorides
Authors: Kojima Tsugio , Satouchi Masaru , Tanaka Yasukazu 
Published: July 2006

Abstract
In the dissociative electron capture reaction of benzyl chlorides, all the substituents in the para position except for t-butyl group tend to decrease the activation energy, those in the meta position having no influence on the activation energy. This can be explained in terms of the contribution of a para substituent to the stabilization of the incipient radical in the transition state resulting from the delocalization of the odd electron. The resonance effect of the para substituent was compared with that obtained in the phenylation of substituted benzenes with phenyl radical, where phenylcyclohexadienyl radical is formed as an intermediate. The resonance effects in these two reactions agree, supporting the reaction mechanism proposed.
The Kinetics of Oxygen Exchange between Arsenate Ions and Water. III. Catalysis by Periodate Ions
Authors: Okumura Akiko , Watanabe Seiko , Sakaue Miyoko , Okazaki Nobukazu 
Published: July 2006

Abstract
Oxygen exchange between arsenate ions and water is remarkably catalyzed by the addition of a small amount of periodate ions. The reaction has been studied at 30.0 °C over the pH range of 6.7–11.4. The rate law of the catalytic reaction has been found to be Rc=k·[H+][As(V)][I(VII)], where Rc is defined as the increase in the rate of oxygen exchange of arsenate ions by the addition of periodate ions. The catalytic process has been interpreted in terms of the reversible condensation of arsenate ions with periodate ions to form the arsenatoperiodate ions, and the rate constant of the condensation reaction between H2AsO4− and H4IO6− has been estimated to be 340 M−1 s−1 at 30.0 °C.