Abstract: A method for preparing ?-keto acids, especially ?-ketomethionine, and/or derivatives thereof, whereby an aldehyde is reacted with thiols to give a corresponding dithioacetal, the dithioacetal formed, is reacted with an electrophile in the presence of a strong base, and the resulting ?,?-(dithio)carboxylic acid is solvolyzed with acid-catalysis to release thiol and give the ?-keto acid or a derivative thereof. Umpolung of aliphatic or aromatic aldehydes is effected by reaction with thiols.

Abstract: The invention relates to a method for production of D- and/or L-methionine via D- and/or L-homoserine with subsequent chemical transformation to give methionine.

Abstract: Ketomethionine ketals and hemiketals and derivatives thereof are useful as feed additives, in particular for the nutrition of ruminants.

Abstract: The present invention relates to a sequence for the preparation of amino acids, for example alpha amino acids, in particular methionine, by making use of an amidocarbonylation reaction and reuse of the catalyst.

Abstract: A method for preparing ?-keto acids, especially ?-ketomethionine, and/or derivatives thereof, whereby an aldehyde is reacted with thiols to give a corresponding dithioacetal, the dithioacetal formed, is reacted with an electrophile in the presence of a strong base, and the resulting ?,?-(dithio)carboxylic acid is solvolyzed with acid-catalysis to release thiol and give the ?-keto acid or a derivative thereof. Umpolung of aliphatic or aromatic aldehydes is effected by reaction with thiols.

Abstract: The present invention relates to the preparation of ?-hydroxy ketones of the general formula I. In particular, the invention relates to novel imidazolinium carboxylate adducts and to a novel process for using catalytic amounts of imidazolium and imidazolinium carboxylate adducts in the acyloin reaction of aldehydes to prepare hydroxy ketones of the general formula I, where R and R? are the same or different and are each H or a straight-chain or branched and optionally substituted C1-C12-alkyl radical, and R??H3CSCH2CH2, t-butyl, n-butyl, sec-butyl, n-propyl, i-propyl, an optionally heteroatom-substituted C6-C18-aryl, heteroaryl, C6-C18-arylalkyl, especially phenylmethyl, where phenyl may again be heteroatom-substituted, or heteroalkyl.

Abstract: The present invention relates to a sequence for the preparation of amino acids, for example alpha-amino acids, in particular methionine, by making use of an amidocarbonylation reaction in the presence of a cobalt carbonyl catalyst and separating the catalyst in the form of a Co(N-amino acid)2 compound.

Abstract: The invention relates to a method for production of D- and/or L-methionine via D- and/or L-homoserine with subsequent chemical transformation to give methionine.

Abstract: Ketomethionine ketals and hemiketals and derivatives thereof are useful as feed additives, in particular for the nutrition of ruminants.

Abstract: The invention relates to a method for production of D- and/or L-methionine via D- and/or L-homoserine with subsequent chemical transformation to give methionine.

Abstract: The present invention relates to the preparation of ?-hydroxy ketones of the general formula I. In particular, the invention relates to novel imidazolinium carboxylate adducts and to a novel process for using catalytic amounts of imidazolium and imidazolinium carboxylate adducts in the acyloin reaction of aldehydes to prepare hydroxy ketones of the general formula I, where R and R? are the same or different and are each H or a straight-chain or branched and optionally substituted C1-C12-alkyl radical, and R??H3CSCH2CH2, t-butyl, n-butyl, sec-butyl, n-propyl, i-propyl, an optionally heteroatom-substituted C6-C18-aryl, heteroaryl, C6-C18-arylalkyl, especially phenylmethyl, where phenyl may again be heteroatom-substituted, or heteroalkyl.

Abstract: A process for the preparation of ?-substituted carboxylic acids from the series including ?-hydroxycarboxylic acids and N-substituted-?-aminocarboxylic acids by cathodic carboxylation with carbon dioxide of a compound corresponding to the general formula R1—C(?X)R2 which is constituted by aldehydes, ketones or N-substituted imines. In the past, that carboxylation has taken place in an undivided electrolytic cell with the use of a sacrificial anode. As described herein, the carboxylation takes place in the absence of a sacrificial anode in an electrolytic cell divided by a separator, at a diamond film cathode. The anode is formed of a material which is stable under electrolytic conditions; in particular, it is a diamond film electrode. The catholyte includes an organic solvent and a conducting salt.

Abstract: The present invention relates to a sequence for the preparation of amino acids, for example alpha-amino acids, in particular methionine, by making use of an amidocarbonylation reaction in the presence of a cobalt carbonyl catalyst and separating the catalyst in the form of a Co(N-amino acid)2 compound.

Abstract: The present invention relates to a sequence for the preparation of amino acids, for example alpha-amino acids, in particular methionine, by making use of an amidocarbonylation reaction and reuse of the catalyst.

Abstract: The invention relates to a method for production of D- and/or L-methionine via D- and/or L-homoserine with subsequent chemical transformation to give methionine.

Abstract: A process for the preparation of ?-substituted carboxylic acids from the series including ?-hydroxycarboxylic acids and N-substituted-?-aminocarboxylic acids by cathodic carboxylation with carbon dioxide of a compound corresponding to the general formula R1—C(?X)R2 which is constituted by aldehydes, ketones or N-substituted imines. In the past, that carboxylation has taken place in an undivided electrolytic cell with the use of a sacrificial anode. As described herein, the carboxylation takes place in the absence of a sacrificial anode in an electrolytic cell divided by a separator, at a diamond film cathode. The anode is formed of a material which is stable under electrolytic conditions; in particular, it is a diamond film electrode. The catholyte includes an organic solvent and a conducting salt.

Abstract: The present invention relates to a process for the racemization of N-acylamino acids of the formula (I) R—CH(NR1COR2)CO2H   (I) in which, in a solvent, an enantiomerically enriched mixture or an enantiomerically pure compound of the formula (I) is reacted in the presence of a transition metal salt, transition metal complex or transition metal complex salt or of a mixture thereof comprising at least one element from the group consisting of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, preferably at a temperature of 10-150° C.

Abstract: The present invention relates to a process for the racemization of N-acylamino acids of the formula (I)