Process for the catalytic production of an analogue of methionine
A method for preparing 2-hydroxy-4-methylthiobutyric acid (HMTBA) or 2-hydroxy-4-methylselenobutyric acid (HMSeBA) by catalytic conversion of 2-hydroxy-4-methylthiobutyronitrile or 2-hydroxy-4-methylselenobutyronitrile, respectively, where said conversion is carried out in the presence of water and at least one weak acid and one catalyst comprising at least one of alumina, titanium dioxide and zirconia.
1 . A method for preparing 2-hydroxy-4-methylthiobutyric acid (HMTBA) or 2-hydroxy-4-methylselenobutyric acid (HMSeBA) comprising catalytically converting of 2-hydroxy-4-methylthiobutyronitrile (HMTBN) or 2-hydroxy-4-methylselenobutyronitrile, respectively, wherein said catalytically converting is carried out in the presence of water and at least one weak acid and one catalyst comprising at least one of alumina, titanium dioxide and zirconia,
wherein said weak acid is selected from formic acid, acetic acid, propionic acid, linear or branched butanoic acid, pentanoic acid, carbonic acid, glycolic acid, thioacetic acid, cyanoacetic acid, lactic acid, pyruvic acid and oxalic acid-,
wherein said catalytically converting consist of converting hydroxy-4-methylthiobutyronitrile or 2-hydroxy-4-methylselenobutyronitrile into 2-hydroxy-4-methylthiobutyric acid or 2-hydroxy-4-methylselenobutyric acid, respectively, and
wherein said conversion is carried out in a single step.
2 . The method according to claim 1 , wherein the molar ratio of the weak acid to 2-hydroxy-4-methylthiobutyronitrile or 2-hydroxy-4-methylselenobutyronitrile, ranges from 0.001 to 50.
3 . The method according to claim 1 , wherein the catalyst is present in a mass concentration of 0.1% to 200% relative to the mass of HMTBN.
4 . The method according to claim 1 , wherein 2-hydroxy-4-methylthiobutyronitrile or 2-hydroxy-4-methylselenobutyronitrile is present in an aqueous solution with a concentration ranging from 0.01 M to 10 M.
5 . The method according to claim 1 , wherein said catalyst has a BET specific surface area of at least 10 m 2 /g.
6 . The method according to claim 1 , wherein said catalyst is doped, with one or more compounds selected from sulfates, phosphates, borates, tungstates, heteropolyacids corresponding to one of the formulas H n XM 12 O 40 and H n X 2 M 18 O 62 in which n is an integer not exceeding 10, X represents Si, Ge, P or As, and M represents Mo or W, and as well as any other doping compound providing acidity to the catalyst.
7 . The method according to claim 1 , wherein the conversion is carried out at a temperature ranging from 20° C. to 200° C.
8 . The method according to claim 1 , wherein it is carried out continuously.