Purification Methods
Dissolve it in CHCl3, dry (MgSO4) concentrate at 40o/70mm, or better at room temperature to avoid decomposition. Wash and stir the residual oil with hexane by decantation and discard the wash. Dry the oil at high vacuum when it should solidify, m 34o. It can be distilled at high vacuum, 80-82o/10-3mm, but this results in extensive losses. The purity can be checked by TLC using Merck Silica Gel F254 and eluting with EtOAc. The azetidinone has RF 0.38 (typical impurities have RF 0.67). The spots can be detected by the TDM spray. This is prepared from (A) 2.5g 4,4'-tetramethyldiaminodiphenylmethane (TDM) in 10mL AcOH and diluted with 50mL of H2O, (B) 5g KI in 100mL of H2O and (C) 0.3g ninhydrin in 10mL of AcOH and 90mL of H2O. The spray is prepared by mixing (A) and (B) with 1.5mL of (C) and stored in a brown bottle. [Clau et al. Justus Liebigs Ann Chem 539 1974, Michel et al. Org Synth 65 135 1987, Beilstein 21/12 V 4.]
