Experiment 3, page 5

onto the column so that the level of liquid is again just flush with the silica surface. Rinse the edges
of the glass with a little more DCM and again force it onto the column. Cover the top of the silica
with fine sand to a depth of ca.1 cm.
Fill the column with x/2 % EtOAc / DCM. Force the solvent rapidly through the column and collect
5 x 10ml fractions. Take care that the bung does not fly out during the operation! Further elute the
column with x % EtOAC / DCM (50ml). Collect a further 10 fractions and check all by t.l.c.
Combine those containing the pure product. Rotary evaporateto dryness in a pre-tared flask.
Check the weight of the residue. Using small volumes of DCM, transfer the residue viafiltration
through a Pasteur pipette containing a cotton wool plug, to a small conical flask. Evaporate (fume
cupboard) to dryness and recrystallise the residue from ethyl acetate. Dry the product under
vacuum overnight at room temperature. Record the yield, m.p., n.m.r. and i.r. spectra and
compare with those of the starting penicillin. Transfer the product to a small labelled sample tube.

Write Up
The write up should conform to the RSC journalOrganic andBiomolecular Chemistrystyle
(Title, Abstract, Introduction, Results and Discussion, Experimental, References). Your
introduction should include discussion of the following points:
a)A full arrow pushing mechanism for the transformation you have carried out.
b)One recent (1998 or later) example from the primary literature of the preparation of β-
lactams.
c)A brief discussion of the antibiotic mode of action of β-lactams.

References and Notes
1.W.C. Still, M. Kahn and A. Mitra, J. Org. Chem., 1978, 43, 2923.
2.R.D.G. Cooper and D.O. Spry, 'Cephalosporins and Penicillins. Chemistry and
Biology', Ed. E.H. Flynn, Academic Press, New York, 1972, p. 183;
P.G. Sammes, Chem. Rev., 1976, 76, 113 and references cited therein.