Ampicillin guaiacol sulphonate prepn. - by reacting ampicillin with guaiacol sulphonic acid in aliph ketone solvent

摘要

Process for prepn. of ampicillin-guaiacol sulphonate of formula (I) comprises reacting anhydrous ampicillin (II) with an approx. stoichiometric amt. of anhydrous guaiacol sulphonic acid (III) in suspension in a 3-6C aliphatic ketone solvent (pref. acetone, MEK or MIBK), the solvent being evapd. under vacuum. (I) is a known antibiotic having the same activity and antibiotic spectrum as (II). It is very soluble in water and may be used as an injectable antibiotic. It is much more stable in dry state than (II) sodium salt and is more rapidly absorbed into the bloodstream than (II). 3H2O.LD50 (rat, p.o.) is 5 g/kg. The known process (It applicn. no. 25646A/70), in which (II) and (III) are reacted in water or alcohol at pH ca. 2, causes degradation of (II) to ampicilloic acid, which has no antibiotic activity and can cause allergic reactions. The present process gives (I) in high yield and purity.