tetrahydrofuran 98 ml the resulting mixture was cooled to 0 u00b0 c and dissolved by addition of dilute ammonia 1 1 18 4 ml 1 1 dilute ammonia is obtained by diluting 1 1 commercially available aqueous solutions with an ammonium hydroxide content of 25 weight by volume obtaining an aqueous solution with a content of ammonium hydroxide of about 14 weight by volume r s o formylmandeloyl chloride 13 8 g dissolved in tetrahydrofuran thf 33 ml is added while maintaining the ph at 6 5 7 0 by gradual addition of 1 1 dilute ammonia the reaction was allowed to proceed at 0 u00b0 c then the solution was washed with methylene chloride analogously to what described for example 2 deformylation differential extraction solvent evaporation and salification were effected analogously to what described in example 2 19 g of product having the following chemico physical properties were obtained ______________________________________elemental analysis as calculated found______________________________________c sub 18 36 86 36 49h sub 16 2 75 3 02n sub 6 14 33 14 12s sub 3 16 40 15 99na sub 2 7 84 7 98______________________________________ 1 h nmr d 2 o u03b4 ppm 3 39 m 1h and 3 68 m 1h cyclic ch 2 s 4 15 dd 1h and 4 40 dd 1h exocyclic ch 2 s 5 05 m 1 h ch at position 6 5 26 s 1h and 5 28 s 1h choh r s 5 50 m 2h ch 2 so 3 5 60 m 1h ch at position 7 7 47 m 5h aromatic protons preparation of 7 2 r 2 hydroxy 2 esahydrophenylacetamido 3 1 sulphomethyl 1 h tetrazol 5yl thiomethyl 3 cephem 4 carboxylic acid.