Patent ID: 7264943

Claim:
A process for the preparation of cephalexin, comprising: contacting an aqueous solution, comprising: (i) 7-aminodeacetoxycephalosporanic acid, and (ii) D-phenylglycinamide, in a ratio from 1:2 to 2:1, with a coated carrier, wherein the carrier comprises crosslinked hydrophilic carrier polymer materials which are able to form covalent bonds in a polymer-analogous reaction with nucleophilic groups of ligands, are in bead form and can be prepared by inverse bead polymerization of a monomer phase which consists of monomers and a diluent, wherein the monomers are: (a) 5-40% by weight of hydrophilic monomers which are capable of free-radical polymerization, have a vinyl group and form at least 10% strength aqueous solutions at room temperature, (b) 30-50% by weight of monomers which are capable of free-radical polymerization and have a vinyl group and an additional functional group which is able to enter into covalent bonds in a polymer-analogous reaction with the nucleophilic groups of the ligands, (c) 20-60% by weight of crosslinking monomers which are capable of free-radical polymerization and have two or more ethylenically unsaturated polymerizable groups, and with the proviso that a), b) and c) add up to 100% by weight, and wherein the diluent is a mixture of methanol and water in the ratio from 1:1.0 to 1:4.0, and wherein the monomer phase is dispersed to droplets in a continuous phase comprising an organic solvent comprising an aliphatic hydrocarbon having 5-7 carbon atoms, and where the ratio of monomer phase to continuous phase is from 1:2.0 to 1:4.0, and in this form undergo free-radical polymerization in the presence of a polymerization initiator and of a protective colloid, with the proviso that the ratio of the monomers to the diluent is from 1:1.7 to 1:2.4, and wherein the carrier polymer materials are coated with penicillin amidase to form the coated carrier.