| 摘要 |
NEW MATERIAL:A compound shown by the formula (n and m are 1 or 2; X is Br or I). EXAMPLE:(6R, 7R)-7-Amino-3-(1-pyridinium)methyl-3-cephem-4-carboxylate .dihy drogenbromide.monohydrate. USE:An intermediate for synthesizing cephalosporin antibiotics. High-purity crystalline salt having improved stability is obtained in high yield from a dilute aqueous solution. PREPARATION:Preferably 3-30% neutral aqueous solution of a compound shown by the formula (n and m are 0) is reacted with 2-5mol based on 1mol compound of hydrobromic acid in 10-20 times as much a water-miscible organic solvent (preferably isopropyl alcohol) as the aqueous solution, to give the monohydrogenbromide.monohydrate. The use of 10 times the molar amount of hydrobromic acid provides the dihydrobromide.dihydrate and this compound is dried under reduced pressure in the presence of phosphorus pentoxide at about 50 deg.C, to give the dihydrobromide.monohydrate.
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