Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Nutritional or dietetic supplement – including table salt
Patent
1997-01-13
1999-11-02
Eisenschenk, Frank C.
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Nutritional or dietetic supplement, including table salt
426425, 426655, 426807, 426656, 562581, 514557, A23L 1305, A23L 128, C15C31502, C15C31506
Patent
active
059766093
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for recovering 2-hydroxy-4-methylthiobutyric acid (MHA), MHA obtainable in accordance with the invention and use of the MHA prepared by this process.
The invention relates in particular to an improved, new type of isolation process for MHA in very high concentration and purity from a reaction mixture resulting during preparation.
BACKGROUND OF THE INVENTION
2-hydroxy-4-methylthiobutyric acid (MHA) is the hydroxyl analogue of the essential amino acid methionin in racemic form and like the latter is an important additive in animal nutrition. When rearing poultry, MHA shows similar growth stimulating properties to those of the amino acid recognised for this purpose. The additive is also being used increasingly in other areas of animal nutrition.
MHA is mostly used in the form of aqueous concentrates, wherein these contain, in addition to the monomer, a certain proportion of oligomers, mainly dimeric and trimeric linear ester acids. The actual amount of these oligomers depends on the conditions of preparation and the concentration selected. Due to their low nutritive action and the inconvenient effect on the flow properties, due to an increase in viscosity, it is desirable, however, to keep their percentage proportion as low as possible. Commercial formulations preferably have, for a total concentration of 88-90 wt. %, up to 24 wt. %, corresponding to ca. 27 mol. % in total of oligomers, corresponding to a monomer/oligomer ratio of .about.3:1.
Use of the calcium salt and mixed calcium ammonium salt of MHA as an animal feed additive is also known. Production of these salts, however, is associated with higher production costs. In addition, as powdered solids they are less easy to incorporate into the feedstuff formulation than readily sprayed aqueous concentrates of the free acids with low proportions of oligomers.
The synthetic route to MHA consists of 3 reactions.
The general process for preparing MHA starts from 3-methylthiopropionaldehyde, also called methylmercaptopropionaldehyde or MMP, which is reacted with hydrogen cyanide to give 2-hydroxy-4-methylthiobutyronitrile, also called MMP-cyanohydrin or MMP-CH (equation 1). ##STR1##
The MMP-cyanohydrin produced is then usually hydrolysed with strong inorganic acids via the intermediate stage of 2-hydroxy-4-methylthiobutyramide, also called MHA-amide (equation II), ##STR2## to give the methionin hydroxy analogue (MHA) (equation III). ##STR3##
This hydrolysis can be performed in either one or two stages, wherein "stages" is understood to mean that inorganic acid and/or water is added either once or twice to hydrolyse the MMP-CH, i.e. the number of stages corresponds to the number of addition processes.
A two-stage method of working starting from MMP-cyanohydrin is described in U.S. Pat. Nos. 2,745,745, 2,938,053 and 3,175,000. There, the cyanohydrin is initially reacted at relatively low temperatures with concentrated inorganic acids, e.g. with 50-85% strength sulphuric acid, to give MHA-amide, whereupon hydrolysis to give MHA is then performed at elevated temperature after the addition of water. The calcium or calcium ammonium salt of MHA and the coupled product calcium sulphate is obtained from this by treating the saponification mixture with calcium hydroxide or carbonate. To avoid the inevitable production of unwanted secondary products, the first two patents mentioned recommend using the hydrolysis reagent sulphuric acid in a sub-stoichiometric ratio to MMP-cyanohydrin of, for example, 0.55-0.8:1. British patent 722 024, which describes a similar method of forming the MHA salts from MHA-amide, also implies the two-stage method of working.
A two-stage hydrolysis is also used in the methods disclosed in European patents 0 142 488 (using sulphuric acid) and 0 143 100 (using inorganic acids), the object of which is the recovery of MHA in a liquid form, that is in highly concentrated aqueous solutions. These are obtained after the hydrolysis reaction, performed under defined concentration and temperature conditions via the a
REFERENCES:
patent: 3175000 (1965-03-01), Gielkins
patent: 4524077 (1985-06-01), Ruest et al.
patent: 4912257 (1990-03-01), Hernandez et al.
Hafner Volker
Hasseberg Hans-Albrecht
Heinzel Harald
Huthmacher Klaus
Tanner Herbert
Degussa - Aktiengesellschaft
Eisenschenk Frank C.
Zeman M K
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