Patent ID: 6743946
Filing Date: 2004-06-01
Classification: C07C

Abstract:
A method for separating 2-hydroxy-4-methylthiobutyric acid (HMTBA) from a 2-hydroxy-4-methylthiobutyronitrile (HMTBN) acid hydrolysate mixture comprising HMTBA and water, comprising the following steps:neutralizing the mixture with aqueous ammonia wherein the amount of water added to the hydrolysate mixture is sufficient to cause the formation of a separate aqueous phase; settling the neutralized mixture to obtain an organic phase and an aqueous phase; separating the organic phase, which comprises HMTBA, water and salts, from the aqueous phase, which comprises HMTBA, water and salts; releasing the salts from the organic phase with an amount of a first organic solvent which is not very miscible with water by contacting said organic phase with said first organic solvent; exhaustively extracting the HMTBA from the aqueous phase with an amount of a second organic solvent which is not very miscible with water by contacting said aqueous phase with said second organic solvent; and evaporating said first and second organic solvents, wherein said first and second organic solvents are the same or different, further wherein most of the salts are precipitated from the aqueous phase after the aqueous phase has been separated from the organic phase.