John O. Edwards

ON THE FORMATION AND REACTIVITY OF DIOXIRANE INTERMEDIATES IN THE REACTION OF PEROXOANIONS WITH ORGANIC SUBSTRATES

Abstract— Kinetics and 18O‐labeling studies have provided evidence for the involvement of dioxirane intermediates (V) in the ketone‐catalysed decomposition of peroxomonosulfate (Caroate) HSO;. Reaction rates depend on ketone structure. In competition with catalysis of peroxide decomposition, the dioxirane intermediate is capable of oxidizing several organic and inorganic substrates. Thus, cis‐ and rrans‐cinnammic acids could be converted stereospecifically into the corresponding epoxides. Also, oxidation of phenylpropiolic acid, a substrate which is representative of weakly nucleophilic alkynes, could be carried out using the Caroatehetone oxidizing system. Under the conditions adopted, no oxidation of the substrates examined was found to occur in the absence of ketone. The possibility that formation of dioxathiirane intermediates (XXII) occurs following a side pathway in the reaction of Caroate with sulfoxides (which produces sulfones in high yield) has been explored. Preliminary experiments using 18O‐labeling of p‐tolyl phenylsulfoxide, however. failed to support this hypothesis. pointing out the need for further detailed studies.

Rate parameters for ligand replacemen processes in octahedral complexes of metal in oxidation state three

Ubersicht uber Aquotisierung, Solvolyse, Isomerisierung und Anionenaustausch, ihren experimentellen Methoden und Einflus vom Oxidationszustand und Grose des Metalls.

A comparative study of polyol complexes of arsenite, borate, and tellurate ions☆

Abstract An investigation using a pH method has been made of the polyol complexes of arsenite, borate, and tellurate ions. The constants obtained for arsenite and borate ions correlate well. The order of values for tellurate complexes does not agree, however, with that for the other two ions; evidence is presented which indicates that the variations in order are caused by steric effects.

Structural principles of the hydrated polyborates

Abstract The principles governing the structures of the stable hydrated polyborates are postulated on the basis of an analysis of the known configurations. The fundamental unit of the polyanionic structures is a trimeric ring containing both trigonal and tetrahedral boron atoms. The formation of the tetramer, pentamers, etc. and long-chain polyanions results from the fusion of two or more rings at the tetrahedral boron atoms, or from dehydration.

A study of cobalt catalysis and copper modification in the coupled decompositions of hydrogen peroxide and peroxomonosulfate ion

The decompositions of HOOH and HOOSO3− in a mixture are mechanistivally linked when cobalt(II) near pH 0 is the catalyst. This linkage, here termed coupling, is seen in the facts that HOOH is an inhibitor of the free radical decomposition of HOOSO3− and the two peroxides are lost in close to a one-to-one ratio. The kinetics of the coupled decompositions have been investigated, and the rate law is −d[HOOSO3−]dtkH[Co2+][HOOSO3−][H+] which holds when [HOOH]≧2×10−2 M. The constant kH is about one-sixth of the value that has been found for the identical rate law for cabalt catalysis of HOOSO3− decomposition in the absence of HOOH. Inhibition is attributed to the trapping of the intermediate Co(III) and possibly also of SO4.− and .OOSO3− by HOOH with consequent formation of HOO. which then reacts by termination only. The presence of the peroxoradical HOO. has been proven through its being trapped by Cu2+, which thereby starts a new and more complicated free radical chain decomposition. The stoichiometry and kinetics of the cobalt-catalyzed, coupled decompositions have been investigated and a tentative set of steps proposed. Some data on copper promotion are reported.

The formation of cobaltic acetate in the catalytic decomposition of peroxyacetic acid

Abstract The kinetics and mechanism for the decomposition of peroxyacetic acid by cobaltous acetate have been investigated. The reaction is first order in peroxyacetic acid and varies from one to one-half order in cobaltous acetate depending on its initial concentration. During the decomposition reaction “cobaltic acetate” is formed. This compound has been isolated and investigated. Evidence is presented which indicates that the compound is [(Ac)2CO(OH)2CO(Ac)2] in which acetate ion is serving as a chelating ligand.

Evidence concerning peroxovanadate structures in solution and their role in catalytic oxidation process

Abstract Evidence concerning the nature of peroxometal intermediates in the oxidation of organic substrates by hydrogen peroxide or t-butyl hydroperoxide by vanadium(V) compounds is critically reviewed; it suggests formation of either metal μ-peroxoester (or peroxoacid) 2 or side-bonded peroxometal intermediates 3. Kinetic and spectroscopic data, as well as comparison with analogous systems, indicate that an entirely different situation arises in the interaction of alkyl hydroperoxides or hydrogen peroxide with the metal center, in that while alkyl hydroperoxides generate metal μ-peroxoester intermediates, H 2 O 2 produces vanadium(V)—side-bonded peroxocomplexes. It is suggested that formation constant ( K t ) values of the peroxometal species and kinetic behaviour in catalytic oxidation permit distinction between these two significantly different modes of binding of the peroxide to the metal.

Fenton Type Activation and Chemistry of Hydroxyl Radical

Nowhere among the multitude of organic compounds is the need for peroxide activation more apparent than among the simple compounds of C, H and O: hydrocarbons, carboxylic acids, alcohols and ethers. In these molecules there are no nucleophilic sites or other types of centers that can react under mild conditions with hydrogen peroxide HOOH. This is well illustrated by the case of polycarboxylic acids which Fenton [1] in 1894 was trying to oxidize with HOOH when he found the strong promotion by ferrous ion.

The reactions of 1, 3-dimercaptopropane, lipoic acid, and dihydrolipoic acid with metal ions

Abstract Solid compounds of α-lipoic acid with Hg2+, and of dihydrolipoic acid and 1,3-dimercaptopropane with Ni2+ and Hg2+ have been prepared. For comparative purposes, qualitative studies have been carried out on the reactions of other metal ions (Zn2+, Cu2+, Co2+ and Pb2+) with these sulfur compounds. With lipoic acid, the product formed readily with Hg2+, but photolytic or thermal cleavage of the disulfide link was necessary before any isolatable products were formed with the other cations. With dimercaptopropane and dihydrolipoic acid, products were formed with all the cations. The importance of these systems is related to the use of lipoic acid in the treatment of heavy metal poisoning.

Coordination compounds with thioxane oxide and thiacyclohexane oxide as ligands. Their use in determination of coordination numbers to oxygen ligands for non-transition metal cations

Abstract Thioxane oxide (TSO) and thiacyclohexane oxide (TCHO) were found to be good ligands for coordination to metal ions, both transition and non-transition. Many new compounds have been prepared. The results with the non-transition metal perchlorates are of particular interest because the ratio of bound sulfoxide molecules to metal cations gives information on the coordination number to oxygen of the metal ions.