Studies On Synthesis,Oxygenation And Biomimetic Catalytic Oxidation Performance Of Crowned Hydroxamic Acids And Their Transition-metal Complexes

Design and synthesis of new functional molecular with crown is an important part in crown chemistry. The investigation of biomimetic oxygen carriers not only has important theoretic significance to reveal reversible bonding and activating oxygen as well as the mechanism of oxidation reaction in organism, but also is potentially applicable in chemically separating oxygen and realizing high efficiency and selectivity of catalytic oxidation reaction under a moderate condition. Hydroxamates complexes have simple and convenient preparation and their structures can be regulated to a great extent as new models of biomimetic oxygen carriers, but there are little the derivatives of crowned hydroxamic acids and no studies on their oxygenatio^ catalytic oxidation and mimetic monooxygenase performance. New crowned hydroxamic acids and their trasition-metal complexes were firstly synthesized. The in-deeper study on the influence of the introduced crown ring, its bonded fashion, position to hydroxamate group and its complexation with the added alkaline (or alkaline earth) cations as well as their distance to the activity center on the dioxygen-affinities, catalytic oxidation of xylene and biomimetic catalytic oxidation performance. Series of useful and creative results have been obtained, which give much helpful information to the design and synthesis of new models of biomimetic oxygen carrier.Hydroxamic acids containing B15C5 and dihydroxamic acids with the bridge group of polyether or dibenzo-crown ether, and their uncrowned analogues were synthesized for the first time, among which thirty-threeligands and sixty transition-metal complexes were unreported and characterized by IR, 1H NMF, MS and elemental analysis.The oxygenation performance of the three series of crowned transition-metal hydroxamates was investigated, their equilibrium constants Ko2 and thermodynamic constants H0, S0 for oxygenation in the pyridine solution were determined, and some dioxygen adducts solid proved to carry oxygen were synthesized. The results indicate: 1. The oxygenation performance of all the crowned hydroxamates was higer than that of the corresponding uncrowed analogues, the dioxygen-affinities of hydroxamates decrease in the order Co2La2> CoLc~ CoLb2; 2. The crown ring and alkaline ion complexed by the crown ether can conduce to the formation and stability of the bond of M-O2-, so the dioxygen-affinities of complexes was improved; 3. The TT-awarding of ligand has the higher influence on the oxygenation performance of complexes than the hydrophobicity and spatial obstacle of ligand.The above crowned models of oxygen carrier were employed as catalysts in catalytic oxidation of xylene, the influence of the structure of complexes and the addition of the alkaline (or alkaline earth) salts on this oxidation was examined. The results indicate: 1. The bonded crown ring can improve the catalytic activity of complexes, the fashion and position of the bonded crown ring as well as the distance between the crown ring and the activity center have the distinct influences on the catalytic activity of complexes, but the structure of the crown ring seem to have no apparent influence; 2. The complexation ability and fashion of the crown ring to the alkaline (alkaline earth) cations have the high influence on the catalytic activity; 3. There are some similar rule and certain relation between the catalytic activity of complexes and their dioxygen-affinities. Generally, the bigger oxygenation constant Ko2) the higher catalytic activity. 4. By the systemic research, we filtrate the catalyst Co2L3a2 and find it have high isomer selectivity to p-xylene in catalytic oxidation of mixed xylene (p-: o-: m-xylene=5:3:2, the content of p-toluic acid is over 97% in the product). 5. The proper explanation of this oxidation mechanism was also given.The monoxygenase-mimicking performance of crown manganese-hydroxmates was firstly checked, with PhIO (or NaOCI) as oxygen source, these complexes were achieved in the catalytic epoxidation of styrene u...