Nitrogenous Character of Penicillin

PENICILLIN purified as described by Abraham and Chain1 contains nitrogen. The interpretation of low positive results in the Dumas analysis of less pure material was made uncertain by the failure to respond to the usual qualitative test and by low results in Kjeldahl estimations. However, traces of pyridine have been recognized, by the characteristic absorption spectrum, as a product of the action of boiling concentrated sulphuric acid on the purest material. With this material the Kjeldahl method, under vigorous conditions, gave the same result as the Dumas. The barium salt, dried at 100° in vacuo over phosphoric anhydride (no further loss at 120°), contains (Weiler and Strauss): C, 44.3; H, 4.85; N, 4.13 (Dumas), 4.2 (independent micro-Kjeldahl); C-Me, 11.6; Ba, 22.0 per cent (independent estimation 21.3). There was no phosphorus or sulphur, and no O-Me or N-Me groups. These results are in fair agreement with the formula C24H32O10N2Ba. This is provisional, and C23 and C25 formulae are not excluded. The barium salt is strongly lsevorotatory in aqueous solution. The absorption spectrum does not suggest that aromatic rings are present in the molecule. Hydrolysis affords one carbon dioxide molecule and other products, including a water-soluble volatile acid, and a substance giving a sparingly soluble picrolonate, flavianate and aurichloride.