Horst Pauling

Synthesis of (all-rac)-α-Tocopherol Using Fluorinated NH-Acidic Catalysts

The synthesis of (all-rac)-α-tocopherol starting from trimethylhydroquinone and isophytol using fluorinated NH-acidic catalysts is described. Scope and limitations of this type of catalysts are discussed. Advantages of this new procedure are high yield and selectivity, no waste problem and mild reaction conditions. Best results in the synthesis of (all-rac)-α-tocopherol (94% yield) using NH-acidic compounds are obtained in polar solvents. The used catalyst could be recovered.

The synthesis of d,l-α-tocopherol in supercritical media

Abstract The synthesis of d , l -α-tocopherol in supercritical carbon dioxide or nitrous oxide by condensation of trimethylhydroquinone (TMHQ) with isophytol (IP) in the presence of various Bronsted or Lewis acids, especially an imide or its metal salts, as catalysts is described. The product is obtained in high yield. The method represents an interesting alternative to existing processes. A quasi-reaction mechanism is being proposed together with kinetics, which are needed for the reactor analysis and design.

Synthesis and Rearrangement of 3-Methyl-1,4-pentadiyne-3-ol †

An efficient synthesis and rearrangement of 3-methyl-1,4-pentadiyne-3-ol (1) using perrhenate- and Mo(VI)-catalysts is reported. The by-products 3,6-dimethyl-1,4,7-octatriyne-3,6-diol (2) and 3-ethynyl-5-methyl-1,6-heptadiyne-3,5-diol (3) were isolated and spectroscopically characterized. A possible reaction mechanism for the formation of the by-products is discussed.

Perfluorinated Brønsted 'superacids': Powerful catalysts for the preparation of vitamin E

The key-step in the industrial synthesis of (all-rac)-a-tocopherol (synthetic vitamin E) is the condensation reaction of trimethylhydroquinone with the C 2 0 building block isophytol. For this Friedel-Crafts-type reaction, perfluorinated NH- and CH-acidic compounds (perfluoroalkyl(aryl)sulfonyl imides and methides) have been applied as excellent catalysts, preferably in biphasic solvent systems.

Dehydration of Aromatic Heterocyclic Carboxamides to Aromatic Heterocyclic Carbonitriles

Phosphorus pentoxide is commonly used for the dehydration of heterocyclic carboxamides to the corresponding nitriles. In this report, the use of cyanuric chloride/N,N-disubstituted formamide for this reaction is described. The advantages of this procedure are mild reaction conditions and good yields. Depending on the reaction conditions and the structures of the amides, the nitriles are obtained in yields from 51% to 99%. Several of the oxazole carbonitriles synthesized by this procedure have not yet been described.