Hydroxyalkanoic acid crystal production method and hydroxyalkanoic acid crystal polymorph
A method for producing a hydroxyalkanoic acid crystal, comprising freeze-drying a solution containing a hydroxyalkanoic acid, wherein based on the total amount of the hydroxyalkanoic acid taken as 100 mass %, (1) the R form content is 95 to 100 mass % or (2) the S form content is 95 to 100 mass %.
1 . A method for producing a 3-hydroxybutyric acid crystal, comprising freeze-drying a solution containing 3-hydroxybutyric acid,
wherein based on the total amount of the 3-hydroxybutyric acid taken as 100 mass %,
(1) the R form content is 95 to 100 mass % or
(2) the S form content is 95 to 100 mass %.
2 . The production method according to claim 1 , wherein the solution containing 3-hydroxybutyric acid contains a polar solvent as a solvent.
3 . The production method according to claim 1 , wherein the polar solvent is water.
4 . A crystalline polymorph of 3-hydroxybutyric acid having diffraction peaks at 2θ=11.9+0.2°, 12.1+0.2°, 15.0+0.2°, 18.8+0.2°, and 20.9+0.2° in a powder X-ray diffraction pattern.
5 . The crystalline polymorph according to claim 4 , wherein the peak angle I at diffraction angle 2θ=12.1+0.2° is the largest.
6 . The production method according to claim 2 , wherein the polar solvent is water.