In a recent communication1 we reported the successful conversion of sarsasapogenin to pregnanediol-3(a),20(a). The fact that this transformation can be accomplished by simple reactions in good yields makes sarsasapogenin one of the cheapest and most practical sources of pregnane derivatives from which it is possible to prepare progesterone, testosterone and desoxycor-
Vol. 66 aliquot of 5 or 10 cc. is withdrawn, by means of a rubber suction bulb connected to a pipet, and hydrolyzed in 10 cc. of distilled water. Titration with standard acid, using phenolphthalein as an indicator, gives the total alkali. Another 5 or 10 cc. aliquot is added to 10 cc. of dry ether containing 1 cc. of benzyl chloride.8 As the alkyllithium solution is dropped into the benzyl chloride, as rapidly as it drains from the pipet, a yellow color flashes through the liquid. If the RLi solution is concentrated, a white precipitate of lithium chloride forms with the disappearance of the yellow color. The ether solution may become warm enough to boil, but it is not cooled. The mixture is allowed to stand one minute after the addition, then hydrolyzed, and titrated with standard acid. Care must be taken not to overstep the end-point in this titration since the aqueous layer decolorizes before the ether layer.This may be overcome by vigorous shaking near the end point.The benzyl chloride must be dissolved in ether because coupling with the RLi compound takes place much less readily in most other solvents. In analyses of RLi compounds prepared in petroleum ether, the benzyl chloride should be dissolved in a relatively large volume of ether.Lithium «-butoxide did not cleave benzyl chloride under the conditions of the analysis. When these two reagents were refluxed for one minute and then hydrolyzed, no chloride ion was found in the aqueous layer.Reaction of Benzyl Chloride with n-Butyllithium.-To a large excess of benzyl chloride (0.6 mole) in ether was added 250 cc. (0.158 mole) of «-butyllithium. Vigorous refluxing took place, even with a moderate rate of addition. The products isolated were: a small quantity of «-octane, 5 g. (21%) of n-amylbenzene, and 8.2 g. (31%) of bibenzyl. The bibenzyl was identified both by a mixed m. p. determination, and by the 1,3,5-trinitrobenzene-bibenzyl complex (m. p. 103-104°).® Incidentally, no bibenzyl was (8) The benzyl chloride was purified by drying user phosphorus pentoxide and then distilling at reduced pressure.
A study has been made of the behavior of certain aliphatic organic acids chiefly typical hydroxy, unsaturated, or keto, toward reduction catalyzed by Raney nickel and in the presence of sodium hydroxide and under high hydrogen pressure.2. At temperatures below 250°and hydrogen pressures not exceeding 330 atmospheres, a-and -hydroxy acids are not affected, whereas ß-hydroxy acids are converted into the corre-sponding unsubstituted acids.3. The unsaturated acids studied were hydrogenated rapidly at temperatures of 100°, or less. 4. a-and y-keto acids were hydrogenated with ease to the corresponding hydroxy acids at quite moderate temperatures. 5. Of particular importance was the conversion, in alkaline solution at 250°and under a hydrogen pressure of 330 atmospheres, of formic acid into methane and carbon dioxide.
Nov., 1938 CONCENTRATION AND PURIFICATION OF PANTOTHENIC ACID FROM LIVER 2719 because of greater reduction 0;' unsaturation by the methyl group in the former than by the hydrogen in the latter. Similarly, large values for formates and small values for branched isomers have been observed in eight pairs of esters by Wenderl6 in a study of parachors previously determined or calculated from previously recorded surface tensions.Experimental.-Surface tensions were measured by Sugden'sa modification of the method of maximum bubble pressure, using m-~ylene'~ in the manometer and carefully purified benzene as a standard'? for calibration of the apparatus. To ensure equal hydrostatic pressures, a maximum stable bubble was left on the large capillary while bubble pressures were being measured from the small capillary. l 3 The manometer readings were taken with a cathetometer with an accuracy of 0.01 cm. Temperatures were controlled to *O0.O8O.After calibration of the bubbler using accepted (16) Simon Wender, Emory University thesis, 1935, unpublished. (17) S. Sugden, J . Chcm. Soc., 118, 1483 (1921). values of benzene (28.88 dynes/cm. at 20°),'* readings were taken to check the calibration of CCb and CeH6C1. The observed values of 26.77 and 33.25 (20') agree with accepted values (26.81 and 33.2). Summary 1. The surface tensions of 15 normal isomeric esters (CleH8202) have been measured at 25, 35, 50, and 65' by the method of maximum bubble pressure.2. The calculated parachors were found to decrease gradually from maxima of 695.3 and 699.1 at the ends of the series to a minimum of 689.3 near the center of the series.3. Molecular volumes calculated from densities taken at constant surface tension (27 dynes/ cm.) varied similarly to parachor.4. The parachors were found to increase, in general, with the temperature.
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