u03b2 1 39 hydroxyethyl cephalosporanate as a single crystalline diastereomer m p 154 5 u00b0 c 155 5 u00b0 c isopropanol identified by nmr and 27 5 mg of t butyl 7 u03b1 1 39 hydroxyethyl cephalosporanate as a mixture of both diastereomers which are separated by high pressure liquid chromatography and characterized by nmr spectroscopy t butyl 7 u03b2 1 39 hydroxyethyl cephalosporanate 4 33 0 mg 0 09 mmoles is dissolved in 1 0 ml of cold trifluoroacetic acid and the mixture is stirred at 0 u00b0 c for 30 minutes the trifluoroacetic acid is removed under reduced pressure and the residue obtained is partitioned between chloroform and dilute aqueous sodium bicarbonate the aqueous phase is separated and acidified to ph 1 5 with 2 5 n hydrochloric acid and is extracted with ethyl acetate the ethyl acetate extract is dried with anhydrous magnesium sulfate filtered and evaporated to give 27 0 mg 97 of 7 u03b2 1 39 hydroxyethyl cephalosporanic acid which is characterized by ir nmr and mass spectrum as ditrimethylsilyl derivative the cephalospranic acid is converted to its corresponding sodium salt by treating an aqueous acetone solution of the acid with a solution of one molar equivalent of sodium bicarbonate in water removing the acetone under reduced pressure and lyophilizing the.