Abstract: Ampicillin is produced in a batch process by enzymatic acylation of 6-aminopenicillanic acid (6-APA) with the aid of phenylglycine derivative such as D-phenylglycine amide. High conversions of phenylglycine derivative may be achieved by having the total concentration in the reaction mixture of 6-APA and ampicillin greater than 250 mM and the molar ration of total quantity of phenylglycine derivative to total quantity of 6-APA less than 2.5. Higher yields of ampicillin may be achieved when the amount of dissolved 6-APA is kept low, e.g. below 300 mM.

Abstract: The invention relates to a process for the preparation of ampicillin in which 6-aminopenicillanic acid (6-APA) is subjected to an enzymatic acylation reaction with the aid of a phenylglycine derivative, with the total concentration of the 6-APA present in the reaction mixture, plus ampicillin, being greater than 250 mM, the concentration of 6-APA in solution being kept lower than 300 mM and the molar ratio of acylation agent to 6-APA which is employed being less than 2.5.

Abstract: Process for the recovery of ampicillin from a mixture containing ampicillin and 6-aminopenicillic acid (6-APA), in which a mixture of ampicillin and 6-APA, with a pH higher than 7, which apart from any solid ampicillin being present is homogeneous at a pH between 7 and 8.5, is subjected to a pH lowering till a pH lower than 8.2 is reached, and the solid substance present is recovered. The process is in particular suitable to be applied to the reaction mixture which is obtained after the enzymatic acylation reaction of 6-APA with a phenylglycidine derivative as acylation agent. Pure ampicillin can thus be recovered in a simple way.

Abstract: The invention relates to a method for the preparation of an .alpha.,.alpha.-disubstituted .alpha.-amino alcohol from the corresponding amide with the aid of sodium in the presence of an alcohol as solvent. The conversion of amino acid amide to amino alcohol proceeds virtually quantitatively. Moreover, the reduction of the amino acid amide to the corresponding amino alcohol proceeds with retention of optical activity.