Method of making a diL-lysine monosulfate trihydrate crystal
A diL-lysine monosulfate trihydrate crystal which has a large tabular form and is more easily separable from the mother liquor is described. The crystal is obtained by a novel process wherein crystallization is conducted at a lower temperature.
1. A method of producing a diL-lysine monosulfate trihydrate crystal characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° as measured by powder X-ray diffraction comprising
a) mixing a lysine solution with sulfuric acid at a temperature of between approximately −10° and approximately 35° C., and allowing said crystal to form, and
b) recovering said crystal.
2. The method of claim 1 , wherein said temperature is between approximately 0° C. and approximately 20° C.
3. The method of claim 2 , wherein said temperature is approximately 10° C.
4. The method of claim 1 , wherein said crystal is recovered by filtration.
5. The method of claim 4 , wherein said filtration is selected from the group consisting of suction filtration, centrifugal filtration, centrifugal separation, and press filtration.
6. A method of producing diL-lysine sulfate comprising
a) mixing a lysine solution with sulfuric acid at a temperature of between approximately −10° C. and approximately 35° C., and allowing a crystal to form,
b) recovering said crystal which is characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction,
c) drying said crystal to remove the crystal water, and
d) collecting said diL-lysine sulfate.
7. The method of claim 6 , wherein said temperature is between approximately 0° C. and approximately 20° C.
8. The method of claim 7 , wherein said temperature is approximately 10° C.
9. The method of claim 6 , wherein said crystal is recovered by filtration.
10. The method of claim 9 , wherein said filtration is selected from the group consisting of suction filtration, centrifugal filtration, centrifugal separation, and press filtration.
11. A method of producing a diL-lysine inonosulfate trihydrate crystal characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction, comprising
a) mixing a lysine solution with sulfuric acid at a temperature above approximately 40° C., and allowing crystals to form,
b) lowering the temperature until it is between approximately −10° C. and approximately 35° C., and allowing crystals to form, and
e) recovering said diL-lysine mono sulfate trihydrate crystal.
12. The method of claim 11 , wherein said temperature in step (b) is between approximately 0° C. and approximately 20° C.
13. The method of claim 12 , wherein said temperature in step (b) is approximately 10° C.
14. The method of claim 11 , wherein said crystal is recovered by filtration.
15. The method of claim 14 , wherein said filtration is selected from the group consisting of suction filtration, centrifugal filtration, centrifugal separation, and press filtration.
16. The method of claim 11 , wherein said diL-lysine monosulfate trihydrate crystal is characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction.
17. A method of producing a diL-lysine monosulfate trihydrate crystal characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction, comprising
a) concentrating an aqueous diL-lysine monosulfate trihydrate solution by evaporation, and allowing a crystal to form, and
b) recovering said crystal.
18. The method of claim 17 , wherein said evaporation occurs under reduced pressure.
19. A method of producing a diL-lysine monosulfate trihydrate crystal charactcrized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction, comprising
a) preparing an aqueous diL-lysine monosulfate trihydrate solution at a temperature above approximately 40° C.,
b) lowering the temperature until it is between approximately −10° C. and approximately 35° C., and allowing crystals to form, and
c) recovering said diL-lysine monosulfate trihydrate crystal.
20. The method of claim 19 , wherein said solution is saturated.
21. A method of producing a diL-lysine monosulfate trihydrate crystal characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction, comprising
a) adding a poor solvent to an aqueous diL-lysine mono sulfate trihydrate solution, and allowing a crystal to form, and
b) recovering said crystal.
22. The method of claim 21 , wherein said poor solvent is methanol, ethanol or 2-isopropyl alcohol.
23. A method of producing a diL-lysine monosulfate trihydrate column crystal characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction, comprising
a) preparing a slurry of diL-lysine monosulfate plate crystals at a temperature above approximately 40° C.,
b) lowering the temperature until it is between approximately −10 to 35° C., and allowing crystals to form, and
c) recovering said crystals.
24. A method of producing diL-lysine sulfate comprising
a) concentrating an aqueous diL-lysine monosulfate trihydrate solution by evaporation, and allowing a crystal to form,
b) recovering said crystal which is characterized by having peaks at diffraction angles 20 of 16.6° and 17.0° in powder X-ray diffraction,
c) drying said crystal to remove the crystal water, and
d) collecting said diL-lysine sulfate.