The layers were separated, and the aqueous portion extracted several times with 5-ml. portions of methylene chloride. The combined methylene chloride extracts were washed with water, dried over magnesium sulfate and concentrated. The residual 2-chloro-2,3,3-trimethyIbutane was purified by sublimation under reduced pressure. The recovery was 0.60 g.The following procedures were used to convert the chloride samples to silver chloride for radioactive assay. A portion of the aqueous hydrochloric acid solution containing about 1-2 millimoles of chloride ion was diluted to 5 ml. with water containing 1 ml. of 6 IV nitric acid. The solution was warmed to about 50°and 10 ml. of 10% silver nitrate solution added rapidly with stirring. The precipitate of silver chloride was collected on a sintered-glass funnel, rinsed several times with acetone and dried in an evacuated desiccator over phosphorus pentoxide. The organic chloride (about 0.1-0.2 g.) was dissolved in 5 ml. of ethanol, warmed to 50-60°and a warm solution of 10 ml. of 10% silver nitrate containing 1 ml. of 6 At nitric acid was added with stirring. The precipitated silver chloride was collected and dried as above.The samples for counting were prepared by weighing out identical amounts of silver chloride on copper dishes previously checked for radioactive contamination. The samples were counted in a methane-filled proportional counter ("Nucleometer," Radiation Counter Laboratories).Trials indicated that the manner of spreading of the samples in the sample dish was not critical provided the samples were spread reasonably evenly. In the experiment described above, the measured activities for 29.0-mg. samples of silver chloride corrected for background with standard deviations were 1309 ± 44 and 15 ± 10 counts per minute for the silver chloride from the original aqueous solution and the organic chloride from the reaction mixture, respectively.In this experiment, the initial reaction mixture contained 98.5 millimoles of hydrochloric acid and 7.4 millimoles of organic chloride. If complete equilibration had occurred, the activity of the organic chloride would be (98.5/106) X 1310 ± 44 = 1220 ± 41 counts per minute. The extent of exchange was thus (15 ± 10/1220) X 100 or 1.2 ± 0.8%. Further experimental results regarding the exchanges are presented in Table II.Cambridge 39, Mass.

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SUMMARY The steroids excreted by patients receiving oral prednisone and oral prednisolone have been investigated. The two compounds present in largest amount were isolated and identified as prednisone and prednisolone. Present in smaller amounts were the corresponding 20β-alcohols. A fifth compound had properties suggestive of pregna-1:4-dien-17α:20α:21-triol-3:11-dione. There is no evidence that prednisone and prednisolone are converted in the body to cortisol, cortisone, or their derivatives, and the investigations suggest that prednisone is metabolized in part by reduction of its 11-ketone group to a 11-hydroxy group and prednisolone by oxidation of its 11-OH group to an 11-ketone group. These two compounds are thus metabolically inter-convertible. Reduction of the 20-ketone group can occur in both compounds.