The invention discloses an alpha-keto-
leucine-
calcium preparation method, comprise the following steps: mixing
hydantoin, alkali and water and heating the solution, then dripping
isobutylaldehyde to perform
reflux reaction, cooling the solution after
reflux reaction, adding strong alkali liquid and cooling the solution after
reflux reaction, extracting and concentrating to obtaining raw liquid alpha-keto-
leucine, dripping the raw alpha-keto-
leucine in the alcoholic solution of
calcium chloride to react and filtrating to obtain alpha-keto-leucine-
calcium. The
reaction mechanism is as follows: adopting
hydantoin to perform
condensation reaction with
isobutylaldehyde in the presence of catalyst, namely alkali to obtain isobutylidene
hydantoin, generating alpha-keto-leucine through
hydrolysis in the presence of strong alkali and salifying to obtain alpha-keto-leucine-calcium. The invention adopts
condensation reaction so that
hydrolysis can be directly realized without separating isobutylidene hydantoin, the equipment utilization can be improved by 30%, the reaction condition is mild and the operation is easier; water is adopted as
solvent, thus lowering the cost and waste water and reducing the
pollution to the environment; in addition, the invention has accessible raw materials and stable product quality, the reaction yield is increased by 10% compared with that of the prior art, and the invention has no special requirement on the equipment, thus being applicable to the industrial production.