Abstract: The invention relates to a method for producing optically active cyanohydrins and the corresponding &agr;-hydroxy-carboxylic acids, starting from an aldehyde, hydrogen cyanide and an optically active vanadyl-salen catalyst, whereby the reaction mixture is reacted at a temperature of between 0 and 60° C. Between 0.8 and 10 equivalents of hydrogen cyanide and between 0.0001 and 0.05 equivalents of vanadyl-salen catalyst in relation to the aldehyde, (concentration of between 0.5 and 4 mol/litre solvent), are preferably used. After said reaction the optically active cyanohydrin or after an acid hydrolysis the corresponding optically active &agr;-hydroxycarboxylic acid can be isolated with a surplus of enantiomers. The vanadium catalyst used in the invention contains a salen ligand, whereby the ratio salen ligand: vanadium (IV) in the catalyst ranges between 1.4:1 and 10:1.

Abstract: The present invention relates to a process for preparing a colour-stable, aqueous dimethylaminoacetonitrile solution from a formaldehyde source, dimethylamine and hydrocyanic acid, wherein the reaction mixture contains 2,4-diamino-6-phenyl-1,3,5-triazine(benzoguanamine) in a concentration of from 0.001 to 5% by weight, based on formaldehyde, prior to the reaction and the starting substances are used stoichiometrically or in a ratio of 0.98-1.02 mol of formaldehyde and 0.95-1.10 mol of dimethylamine per mol of hydrocyanic acid. The resulting product remains colour-stable without a further purification step even after prolonged storage.

Abstract: The present invention relates to a process for preparing a colour-stable, aqueous dimethylaminoacetonitrile solution from a formaldehyde source, dimethylamine and hydrocyanic acid, wherein the reaction mixture contains 2,4-diamino-6-phenyl-1,3,5-triazine (benzoguanamine) in a concentration of from 0.001 to 5% by weight, based on formaldehyde, prior to the reaction and the starting substances are used stoichiometrically or in a ratio of 0.98-1.02 mol of formaldehyde and 0.95-1.10 mol of dimethylamine per mol of hydrocyanic acid. The resulting product remains colour-stable without a further purification step even after prolonged storage.