Kinetics And Mechanisms Of The Oxidation Of Alkyl Benzene Sulfonates And Aldehydes By Potassium Ferrate(Ⅵ) And Manganese Nitrido Complexes

Over the past few decades,the research of high-valent metal-nitrides and oxo complexes has attracted more and more attention.This thesis is mainly composed of two parts.One is the study of the kinetics and mechanisms of the reactions between ferrate[and 4-alkylbenzene sulfonates;the other one is the kinetic and mechanistic study of the reaction of manganese nitrido complexes with aldehydes.Ferrate（Ⅵ）,[Fe O₄]^2-,is a very powerful oxidant that can oxidize a wide variety of inorganic and organic compounds.However,the mechanisms of many of these oxidation reactions have not been studied in detail.In this work,we have investigated the kinetics and mechanism of the oxidation of 4-alkylbenzene-sulfonates by ferrate in aqueous solutions at p H 7.45–9.63 by UV/Vis spectrophotometry.The reactions are first order with respect to both[ferrate]and[4-alkylbenzenesulfonate].The second-order rate constants for the oxidation of 4-isopropylbenzenesulfonate by ferrate at 25°C and I=0.3 M are found to be（5.86±0.08）×10^-1 M^-1s^-1 and（4.11±1.50）×10^-3 M^-1s^-1 for[Fe（O）₃（OH）]^-and[Fe O4]^2-,respectively,indicating that[Fe（O）₃（OH）]^-is two orders of magnitude more reactive than[Fe O₄]^2-and is the predominant oxidant in neutral and slightly alkaline solutions.This is further supported by the effect of the ionic strength on the rate constant.No solvent kinetic isotope effect（KIE）was found but a moderate primary KIE=1.6±0.1 was observed in the oxidation of 4-ethylbenzenesulfonate and 4-ethylbenzenesulfonated9.Alkyl radicals were trapped by CBr Cl₃ in the oxidation of alkylarenes by ferrate.Combined with DFT calculations,a hydrogen atom transfer（HAT）mechanism was proposed for the reactions between[Fe（O）₃（OH）]^-and 4-alkylbenzenesulfonates.（Salen）Mn（N）complex has been known for a long time,but it does not react with organic substrates due to its low activity.In this work,we found that oxygen could promote the reaction of Mn nitrido complex with aldehydes.The kinetics were studied by UV/Vis spectrophotometry following the wavelength of 400 nm and 600 nm.Two phases were observed.The first increase phase was studied by initial rates,which depends on[aldehyde].No KIE was observed for the initial rate,but a large KIE observed for the average rates of the increase phase.The decrease phase follows pseudo first-order reaction and the rate constants are independent of both[Mn N]and[benzaldehyde]For the products,amides and carboxylic acids were found.Mn（III）carboxylate complexes were isolated.The mechasim is the nuclephilic attack of carbonyl carbon of aldehydes,followed by oxidation by oxygen,resulting in radical oxidation reaction.