Manganese catalysed oxidations with hydrogen peroxide:applications and mechanistic insights

Het doel van het onderzoek dat in dit proefschrift wordt beschreven was het ontwikkelen van nieuwe milieuvriendelijke en economisch duurzame methoden voor de selectieve oxidatie van organische verbindingen, in het bijzonder cis-dihydroxylering en epoxidatie van alkenen, oxidatie van alcoholen en aldehyden en selectieve C-H activatie. De voornaamste uitdaging was om deze reacties uit te voeren met een eenvoudige katalysator gebaseerd op mangaan en met waterstofperoxide. Tijdens het onderzoeksproject werd al snel een belangrijke doorbraak gemaakt: de ontdekking van een compleet nieuwe katalysator concept dat meteen geschikt was voor toepassingen op zowel het lab als in de industrie en het werd vervolgens gepatenteerd in samenwerking met industriële partners in het project. De voornaamste focus van het promotieonderzoek was om te ontrafelen hoe dit katalysator systeem werkt en om te komen tot verbeterd inzicht zodat het katalysator systeem nog bredere toepassing kan vinden in de toekomst

Oxidation of Vicinal Diols to -Hydroxy Ketones with H2O2 and a Simple Manganese Catalyst

-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic-diols to -hydroxy ketones with H2O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the Mn-II catalyst and H2O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to -hydroxy ketones can be achieved under mild (ambient) conditions

Oxidative Cleavage of Alkene C=C Bonds Using a Manganese Catalyzed Oxidation with H2O2 Combined with Periodate Oxidation

A one-pot multi-step method for the oxidative cleavage of alkenes to aldehydes/ketones under ambient conditions is described as an alternative to ozonolysis. The first step is a highly efficient manganese catalyzed epoxidation/cis-dihydroxylation of alkenes. This step is followed by an Fe(III) assisted ring opening of the epoxide (where necessary) to a 1,2-diol. Carbon-carbon bond cleavage is achieved by treatment of the diol with sodium periodate. The conditions used in each step are not only compatible with the subsequent step(s), but also provide for increased conversion compared to the equivalent reactions carried out on the isolated intermediate compounds. The described procedure allows for carbon-carbon bond cleavage in the presence of other alkenes, oxidation sensitive moieties and other functional groups; the mild conditions (r.t.) used in all three steps make this a viable general alternative to ozonolysis and especially for use under flow or continuous batch conditions

Manganese-Catalyzed Selective Oxidation of Aliphatic C-H groups and Secondary Alcohols to Ketones with Hydrogen Peroxide

An efficient and simple method for selective oxidation of secondary alcohols and oxidation of alkanes to ketones is reported. An in situ prepared catalyst is employed based on manganese(II) salts, pyridine-2-carboxylic acid, and butanedione, which provides good-to-excellent conversions and yields with high turnover numbers (up to 10 000) with H2O2 as oxidant at ambient temperatures. In substrates bearing multiple alcohol groups, secondary alcohols are converted to ketones selectively and, in general, benzyl C-H oxidation proceeds in preference to aliphatic C-H oxidation.

Mechanisms in manganese catalysed oxidation of alkenes with H2O2

<p>The development of new catalytic systems for cis-dihydroxylation and epoxidation of alkenes, based on atom economic and environmentally friendly concepts, is a major contemporary challenge. In recent years, several systems based on manganese catalysts using H2O2 as the terminal oxidant have been developed. In this review, selected homogeneous manganese catalytic systems, including 'ligand free' and pyridyl amine ligand based systems, that have been applied to alkene oxidation will be discussed with a strong focus on the mechanistic studies that have been carried out.</p>

Conformational Analysis and Binding Properties of a Cavity Containing Porphyrin Catalyst Provided with Urea Functions

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