Pierre A. Jacobs

¹H NMR can be used to determine the epoxide yield rapidly in the oxidation of squalene. Moreover, unequivocal distinction can be made between internal and terminal epoxide bonds. To underline the power of this technique, different stoichiometric and catalytic epoxidation procedures were carried out using squalene as substrate. They were characterized in terms of substrate conversion and regioselectivity of the epoxide fraction.

An efficient and benign method for the regio‐ and stereoselective synthesis of halohydrins and β‐halo ethers from dihydropyrans, dihydrofurans and anhydro sugars in the presence of a halide salt and hydrogen peroxide is presented with tungstate‐exchanged takovite as oxidation catalyst.

Acid zeolites were screened as heterogeneous catalysts for racemization of benzylic alcohols. The most promising zeolites appeared to be H‐Beta zeolites, for which the optimal reaction conditions were studied in further detail. The zeolite performance was compared to that of homogeneous acids and acid resins under similar reaction conditions. In a second part of the research, H‐Beta zeolites were applied in dynamic kinetic resolution (DKR) of 1‐phenylethanol, which was conducted by means of a two‐phase approach and which resulted in yields smoothly crossing the 50 % border up to 90 %, with an enantiomeric excess of >99 %. To explore the applicability of this biphasic methodology, several other substrates were examined in the standard racemization reaction and in the biphasic dynamic kinetic resolution.

Product mixtures of epoxidized fatty compounds can be analyzed by using ¹H NMR. Conversion of double bonds and selectivities to different products can easily be calculated. Moreover, if diunsaturated substrates are used in epoxidation reactions, yields to mono‐ and diepoxidized products can be determined. The effectiveness of this method is proven by comparing some NMR results with those found by GC analysis.

The oxidation of furan derivatives with titanium silicalite 1 (TS‐1) and hydrogen peroxide is described. Oxidation products are identified and possible reaction pathways are discussed. It is shown that the oxidation of these compounds occurs via epoxidation of one of the furan double bonds. The initially formed epoxides immediately undergo rearrangement, furans yielding unsaturated 1,4‐dicarbonyl compounds and furfuryl alcohols yielding 6‐hydroxy‐2H‐pyran‐3(6H)‐ones. The latter compounds originate from cyclization of intermediate enedione alcohols. The presented method is particularly useful for the oxidation of 2,5‐dimethylfuran to 3‐hexene‐2,5‐dione and the conversion of furfuryl alcohol to 6‐hydroxy‐2H‐pyran‐3(6H)‐one, a versatile synthon in organic synthesis.