Purification Methods
Crystallisation of the acid from 95% EtOH and drying it in a vacuum desiccator (12mm) over P2O5 gives the monohydrate mixture of and anomers (mostly -) as white micro needles, which sinter at ~100-111o and melt at 159-160o, [] D 20 +107o (initial, c 4 in H2O mutarotating to +51o). [Link & Sell Biochemical Preparations 3 74, 78 1953, Beilstein 3 IV 2000.] The -anomer is obtained by warming the -anomer in EtOH, AcOH or EtOAc and has m 1 6 0o (165o, sinters at 1 4 0o), [] D 20 +27o (initial, c 2 in H2O mutarotating to +55.3o in 24hours). The sodium salt [14984-39-5] M 216.1 has [] D 20 +27o (c 10 in H2O after 5hours). The phenylhydrazone has m 141o(from MeOH). [Ehrlich & Schubert Chem Ber 62 1974, 2014 1929, Anderson & King J Chem Soc 5333 1961, Beilstein 3 IV 2001.]
