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AssigneeDegussa AG
InventorsHelmut Suchsland, Volker Hafner
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Known processes for producing 2-hydroxy-4-methylthiobutyric acid (MHA) use a liquid-liquid extraction or a combined liquid/liquid and solid/liquid phase separation to isolate MHA from a reaction mixture produced by hydrolysing MMP-cyanhydrine. These processes are either costly or produce waste that is difficult to dispose of. These disadvantages are eliminated by isolating MHA by solid/liquid separation. The reaction mixture is evaporated until a MHA-containing salt residue with little or no residual water is obtained the MHA-containing, salt residue is treated with an organic solvent to produce a suspension, solid components are separated from the thus obtained suspension until a MHA-containing solution is obtained, the organic solvent is removed from the MHA-containing solution until a MHA residue is obtained and if required the MHA residue is then conditioned by water admixture. Besides high quality MHA, this process produces marketable crystalline ammonium sulphate and/or hydrogenated ammonium sulphate. This process is useful for producing feedstuff supplements.
A process for producing 2-hydroxy-4-methylthiobutyric acid (MHA) in which the MHA is isolated from a reaction mixture obtained by the attachment of hydrogen cyanide (HCN) to methylmercaptopropionaldehyde (MMP) and by hydrolysis of the methylmercaptopropionaldehyde cyanohydrin (MMP-CH) obtained thereby with sulfuric acid which comprises (a) concentrating the reaction mixture by evaporation under conditions to obtain an MHA-containing salt residue substantially free of residual water,(b) subsequently treating the MHA-containing salt residue with an organic solvent under conditions to form a suspension, (c) separating solid components from the suspension under conditions to obtain an MHA-containing solution, (d) removing the organic solvent from the MHA-containing solution and recovering an MHA residue and, wherein the MHA residue is conditioned thereafter, if necessary, by the addition of water.
A process for producing 2-hydroxy-4-methylthiobutyric acid (MHA) in which the MHA is isolated from a reaction mixture obtained by the attachment of hydrogen cyanide (HCN) to methylmercaptopropionaldehyde (MMP) and by hydrolysis of methylmercaptopropionaldehyde cyanohydrin (MMP-CH) obtained thereby with sulfuric acid wherein the MHA isolated from the reaction mixture comprises a solid/liquid separation in which an essentially gelatinous or solid MHA-containing salt residue is treated with an organic solvent.
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