Process for the isolation of L-amino acids

• US 4,827,029 A
• Filed: 01/21/1988
• Issued: 05/02/1989
• Est. Priority Date: 01/30/1987
• Status: Expired due to Term

• Current Assignee: Degussa AG (Rag-Stiftung)
• Original Assignee: Degussa AG (Rag-Stiftung)
• Inventors: Moerck, Rudi E., Karrenbauer, Michael, Klostermann, Kurt, Kleemann, Axel, Leuchtenberger, Wolfgang
• Primary Examiner(s): Reamer, James H.
• Application Number:
  US07/146,637
• Time in Patent Office: 467 Days
• Field of Search: 562/443, 562/444, 562/559, 562/575, 562/402
• US Class Current: 562/559
• CPC Class Codes: C12P 13/04 Alpha- or beta- amino acids other amino acids C12P13/005

Abstract

L-amino acids present in cleavage solutions obtained in the acylase-catalyzed cleavage of N-acetyl-D,L-amino acids are isolated by use of a strongly acidic ion exchanger in H+ form. First, the mother liquor from a previous treatment cycle is fed to the ion exchanger, and then the cleavage solution and finally the wash water and the discharge from the ion exchanger which is pH-controlled is analyzed into an "effluent water fraction", an "N-acetyl-D-amino acid fraction" and an "L-amino acid fraction". The last fraction is adjusted by addition of fresh cleavage solution to a pH of between 4.0 and 6.0, and from the mixture which is thus obtained the L-amino acid is isolated by crystallization. The mother liquor which is obtained is recycled back into a subsequent treatment cycle.

Claims

1. A process for the isolation of L-amino acids from the cleavage solutions obtained in the acylase-catalyzed cleavage of N-acetyl-D,L-amino acids in the presence of a strongly acidic ion exchanger in the H+ form, comprising:

charging an ion exchanger column maintained at a temperature of between 30° and

90°

C., with cleavage solution obtained from the cleavage of N-acetyl-D,L-amino acids, contacting said ion exchanger with wash water,

separating the discharge from the ion exchanger under pH control into three fractions, of which the first fraction extends from the beginning of the treatment process until the pH of 2.0 is reached, and of which the second fraction extends from pH 2.0 until the pH after falling below 2 rises back to 2.0 again, and of which the third fraction extends from the point terminating the second fraction during the feed of the cleavage solution until a pH of 5.0 is reached,

combining said third fraction with the discharge being obtained during the feed of the wash water and adding thereto fresh cleavage solution to adjust the pH of the mixture of between 4.0 to 6.0,

isolating the L-amino acid from the said adjusted mixture by crystallization, and recycling the mother liquor which is thus obtained back into a subsequent treatment cycle.

2. The process according to claim 1 wherein the ion exchanger is operated at a temperature of between 60°

and 80°

C.

3. A process according to claim 1 wherein the mixture of the third fraction with the discharge being obtained during the feed of the wash water by addition of fresh cleavage solution is set at a pH of between 4.5 and 5.5.

4. A process for the isolation of L-amino acids from the cleavage solutions accumulating during the acylase-catalyzed cleavage of N-acetyl-D,L-amino acids in the presence of a strongly acidic ion exchanger in the H+ form, comprising:

carrying out an ion exchange at a temperature of between 30° and

90°

C., in a first step by contacting mother liquor having been obtained from a previous treatment cycle with said ion exchanger,

in a second step contacting said ion exchanger with cleavage solution obtained in said cleavage of N-acetyl-D,L-amino acids, and

in a third step contacting said ion exchanger with washing water,

separating the discharge from the ion exchanger under pH control into three fractions, of which the first fraction extends from the beginning of the reaction until the pH of 2.0 is reached, and of which the second fraction extends from pH 2.0 until the pH after falling below 2 then rises to 2.0 again, and of which the third fraction extends from the point terminating the second fraction during the feed of the cleavage solution until a pH of 5.0 is reached,

combining said adjusted third fraction with the discharge being obtained during the feed of the wash water and adding thereto fresh cleavage solution to adjust the pH of the mixture to a value between 4.0 to 6.0,

isolating the L-amino acid from the said mixture by crystallization, and recycling the mother liquor which is thus obtained back into a subsequent treatment cycle.

5. The process according to claim 4 wherein the ion exchanger is operated at a temperature of between 60°

and 80°

C.

6. A process according to claim 4 wherein the mixture of the third fraction with the discharge being obtained during the feed of the wash water by addition of fresh cleavage solution is set at a pH of between 4.5 and 5.5.