Abstract: A process for preparing substituted pyridine N-oxide compounds of the formula in which R1, R2, R3 and R4 are each H, a carboxyl group or a C1-C12-alkyl radical which may contain atoms from the group of N, O and S, or R1 and R2 and/or R3 and R4 together may each form an optionally substituted C4-C20-alkylene radical which may contain atoms from the group of N, O and S, A is benzyl or a (CH2)m group where m may be an integer from 1 to 12, Z1 and Z2 are each independently O or S, and Y is H, a C1-C12-alkyl radical which may optionally contain atoms from the group of N, O and S, a C6-C20-aryl radical or a C5-C20-heterocycle, and the radicals may optionally be substituted, or Z2 and Y together form an optionally substituted ring or ring system, in which case the ring or ring system may contain atoms from the group of N, O and S, from the corresponding 4-halopyridine N-oxide of the formula in which X is chlorine, bromine or iodine, by reacting the compound of the formula (II)

Abstract: Process for the preparation of optically highly pure (R)- and (S)-&agr;-hydroxycarboxylic acids, in which either isolated, impure (R)- and (S)-&agr;-hydroxycarboxylic acids prepared by acidic hydrolysis of the (R)- and (S)- cyanohydrins obtained by enzyme-catalyzed addition of a cyanide group donor to the corresponding aldehydes or ketones are recrystallized in an aromatic hydrocarbon, optionally in the presence of a cosolvent, and optically highly pure (R)- and (S)-&agr;-hydroxycarboxylic acids having an optical purity of over 98%ee are obtained or the hydrolysis solution obtained by acidic hydrolysis of the (R)- and (S)-cyanohydrins is treated directly with an aromatic hydrocarbon, optionally in combination with a cosolvent, and is then extracted at hydrolysis temperature, whereupon after cooling of the organic phase the corresponding chemically and optically highly pure (R)- and (S)-&agr;-hydroxycarboxylic acids having an optical purity of over 98%ee crystallize out.

Abstract: The invention relates to the production of (R)-enantiomeric, optically active cyanohydrins by reacting an aldehyde or a ketone with a cyanide group donor in the presence of (R) oxynitrilase, wherein a reaction mixture comprising a) an aldehyde or a ketone dissolved in an organic solvent; said organic solvent is immiscible or only slightly miscible with water, b) any aqueous R)-oxynitrilase solution and c) a cyanide group donor is stirred in such away that an emulsion is formed which remains intact until the end of the enzymatic reaction. After the enzymatic reaction has terminated, the (R)-cyanohydrin is isolated from the reaction mixture.

Abstract: The invention relates to a method for producing 2-oxindoles from the corresponding isatines of formula (I), wherein R can be H, CH3, phenyl or benzyl and R1 can be H, C1-C4-alkyl, C1-C4-alkoxy, phenyl phenoxy, halogen, amino, nitro or hydroxy. Said isatines are converted by means of hydrazine hydrate in a polar solvent at a temperature of 15 to 185° C. to form a corresponding isatine hydrazone which directly undergoes further reaction to form the corresponding 2-oxindole of formula (II) by adding diazabicyclooctane and/or diazabicycloundecane and/or ethyldiisopropylamine as a catalyst in temperatures of 100 to 185° C., whereby the produced reaction water is distilled off. According to formula (II), R and R1 have the aforementioned definitions. The 2-oxindole is isolated from the reaction mixture by distilling off the solvent and by means of crystallisation.

Abstract: The invention relates to the use of one or more &agr;-keto carboxylic acid esters and/or aldehyde carboxylic acid esters for stabilizing hydrogen peroxide during enzyme-catalyzed or metal-catalyzed oxidation reactions in organic synthesis, as well as for stabilizing hydrogen peroxide or aqueous or organic hydrogen peroxide solutions during production, storage and transport.

Abstract: Process for the oxidation of aldehydes to the corresponding acids in which an aldehyde as substrate is oxidized to the corresponding acid in the presence of an equimolar amount, or a molar excess, of periodate, catalytic amounts of dichromate or CrO3, and in the presence of an acid in water, a water/solvent mixture or in a solvent at a temperature of −20° C. to +50° C.

Abstract: Improved, safe process for the purification of ketones obtained by ozonolysis and subsequent reduction of the corresponding terpenes, in which, after the ozonolysis and reduction of acyclic mono-, bi- or tricyclic terpenes with ozonizable double bonds, converting the resulting corresponding crude ketone into a high-purity ketone by means of steam distillation at atmospheric pressure or at reduced pressure, extraction of the steam distillate and subsequent distillation.

Abstract: Improved process for the purification and formulation of o-phthalaldehyde in which crude o-phthalaldehyde, obtained by cleavage of an acetal of o-phthalaldehyde by means of acidic hydrolysis, is, optionally by adding an aqueous basic solution, adjusted to a pH of from 1 to 8, and then, after phase separation has taken place, water is distilled off from the phase which contains the aldehyde with very short thermal stress of less than 1 minute at a pressure of between 100 mbar and atmospheric pressure and a temperature of from room temperature to 180° C. on a thin-layer overhead evaporator and o-phthalaldehyde is then stripped off from the distillation bottom which remains with very short thermal stress of less than 1 minute at a pressure of from 0.5 to 50 mbar and a jacket temperature of from 80 to 80° C. via a thin-layer evaporator and the resulting o-phthalaldehyde melt is pelleted at atmospheric pressure and a temperature of from 60 to 80° C.

Abstract: The invention relates to a method for oxidizing organic substrate by using 1O2. According to the inventive method, organic substrates that react with 1O2 are mixed with 30-70% H2O2 in water, in an organic solvent or in a mixture thereof in the presence of a lanthanide as the catalyst. H2O2 is catalytically decomposed to water and 1O2 and is then oxidized to the corresponding oxidation products.

Abstract: The invention relates to a method for producing hydroxymethylpyridines from the corresponding vinylpyridines by means of ozonisation in an alcohol as solvent and by means of hydrogenation of the peroxide-containing solution produced thereby, in the presence of a hydrogenation catalyst The hydrogenation solution is adjusted to a pH value of 10 to 14 by adding a base and the alcohol is distilled off and the desired hydroxymethylpyridine is isolated in high purity by extracting with an organic solvent and by means of subsequent distillative purification.

Abstract: A process for the preparation of enantiomer-enriched aminofuranones and hydroxyfuranones in which an enantiomer-enriched cyanohydrin is acylated by an acylating agent, then cyclized at 40 to 90° C. in the presence of zinc or a zinc compound to the corresponding enantiomer-enriched aminofuranone, which is converted where appropriate by acid hydrolysis into the corresponding enantiomer-enriched hydroxyfuranone.

Abstract: A process for the selective enzymatic hydroxylation of aldehydes and ketones using chiral anchor-protective groups.