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Experiment 3, page 5

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 deth 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 evaporate to 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 a J. Chem. Soc., Perkin Trans. I, style (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)Three recent (1993 or later) examples from the primary literature of preparations and/or
manipulations of b-lactams. Extra marks for originality and breadth of chemistry! c)A brief discussion of the antibiotic mode of action of b-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.

Steve Marsden/ 21/9/98