TH36727A - Process for the purification of valine - Google Patents

Abstract

This invention provides a process for the high-purity, high-yield purification of valine using a simple method employing inexpensive precipitates. An aqueous solution containing valine is reacted with para-isopropylbenzene sulfonate or its water-soluble salts to form valine para-isopropylbenzene sulfonate crystals. The valine para-isopropylbenzene sulfonate is then separated and further purified to obtain valine. Para-isopropylbenzene sulfonate may exist as a free acid, an alkali metal salt, or an ammonia salt. The process of formation using 1 mole of valine and 1 mole of para-isopropylbenzene sulfonate and subsequent valine purification is highly efficient due to the low solubility of valine para-isopropylbenzene sulfonate. It can be separated at a high rate from leucine and isoleucine, which are generally difficult to separate from valine due to the specific gravity of the axial conductor. Para-isopropylbenzene sulfonate acid can be easily produced by sulfonating inexpensive isopropylbenzene.

Claims (20)

1. Crystalline valine para-isopropylbenzene sulfonate consists of the reaction product of the molar equivalent amounts of valine and para-isopropylbenzene sulfonate acid. 2. The process for purifying valine involves the contact of a valine-containing solution with para-isopropylbenzene sulfonate acid or its aqueous salts to form valine para-isopropylbenzene sulfonate crystals in a solution medium. This is followed by the separation of the valine para-isopropylbenzene sulfonate crystals from the solution medium and the subsequent separation of valine para-isopropylbenzene sulfonate into valine. 3. The process under claim 2, in which the water-soluble salt of para-isopropylbenzenesulfonic acid is an alkali metal salt. 4. The process according to claim 2, in which the separation step is performed by adding sufficient hot water to dissolve the valine para-isopropylbenzene sulfonate crystal and passing the resulting solution through a weak base ion exchange column, immobilizing para-isopropylbenzene sulfonate acid to the column and allowing valine to pass through the column as an elute. 5. The process under claim 2, in which the separation step is performed, involves the preparation of a suspension of para-isopropylbenzene sulfonate crystals in aqueous water and the addition of sufficient alkali hydroxide to adjust the pH of the suspension to between 5 and 8 in order to separate the para-isopropylbenzene sulfonate crystals, resulting in the insolubility of para-isopropylbenzene sulfonic acid and the precipitation of free valine. 6. The process under claim 5, where the pH is adjusted to a value between 6 and 7. 7. The process under claim 2, in which the contact procedure is performed by adding the said para-isopropylbenzene sulfonic acid or its aqueous salts to the said valine-containing solution, which contains at least 3 g/L of valine, and adjusting the pH of the resulting solution to between 0.1 and 2.3. 8. The process under claim 7, in which the pH adjustment is performed, involves the use of inorganic acids. 9. The process under claim 8, in which the inorganic acid is selected from hydrochloric acid or sulfuric acid. 10. The process pursuant to claim 7 involves adjusting the pH to a value between 1.0 and 1.7. 11. The process under claim 10, in which the pH value is adjusted to 1.5. 12. The process under claim 2, in which the separation step is performed by filtering. 13. The process under claim 2, in which the separation procedure is carried out by centrifugation. 14. The process under claim 2, which, following the separation step, involves the isolation of valine and the reuse of para-isopropylbenzene sulfonic acid in the contact step. 15. The process under claim 2 in which the valine is selected from a group consisting of L-valine, D-valine, DL-valine, and mixtures thereof. 16. The process under claim 2, in which the valine solution is obtained from the digestion of proteins. 17. The process under claim 2, in which the valine solution is obtained from the fermentation of valine-producing microorganisms. 18. The process under claim 2 in which the said valine solution is obtained by the fermentation of microorganisms that produce and accumulate valine, and the isolation of the microbial cells from the said solution. 19. The process under claim 2, in which the said valine solution is a solution of DL-valine synthesized by a hydrentoin derivative production method, is contaminated in the said solution. 20. The process under claim 2, in which the contact procedure involves the addition of 1.0 to 1.1 moles of para-isopropylbenzene sulfonic acid or its aqueous salts to a valine-containing solution.