Process for producing ammonium-2-hydroxy-4-(methylthio)-butyrate, mixtures containing the same in liquid form and their use

A process for producing ammonium-2-hydroxy-4-methylthio-n-butyrate (MHAAS) comprising:

• a) isolating 2-hydroxy-4-methylthio-butyric acid (MHA), which MHA also contains dimers and higher oligomers, from a first reaction mixture wherein said first reaction mixture is obtained by attachment of hydrogen cyanide (HCN) to methylmercaptopropionaldehyde (MMP) followed by mineral-acidic hydrolysis of methylmercaptopropionaldehyde cyanohydrin (MMP-CH) so formed, with ammonia, to form a second reaction mixture,
• b) treating the second reaction mixture, resulting from step (a), with an inert solvent non-miscible or partially miscible with water to obtain a first organic extract and a first aqueous raffinate consisting essentially of ammonium chloride;
• c) decomposing the first organic extract by treatment with ammonia under phase separation conditions into a second organic extract and a second aqueous raffinate,
• d) reextracting the MHA as MHAAS into the second aqueous raffinate taking place with formation of salt, and
• e) isolating the MHAAS in an odorless free flowing solution from the second aqueous raffinate.