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COMMUNICATIONS TO THE EDITOR
obtained, to the liquefaction pressure P, of the gas a t temperature T. Nitrogen isotherms for the above two temperatures have also been obtained for a pure iron and a doubly promoted iron catalyst. In all of these cases the adsorption of a given gas on a particular catalyst at two or more temperatilres could be represented by a single potential curve of the type shown in Fig. 2.
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with temperature, the 183 and - 195.8’ points falling on the same curve. The significance of this &It is not certain as yet. BUREAUOF CHEMISTRY AND SOILS P. H. EMMETT U. S. DEPARTMENT OF AGRICULTURE STEPHEN BRUNAUER D. C. WASHINGTON, RECEIVED NOVEMBER 1, 1935
THE AUTO-OXIDATION OF KETONES
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Sir: Several ketones of the type R’COCH,R (R = phenyl) on standing in the presence of light and air for varying periods of time were observed to acquire an aldehyde-like odor. On further investigation it was found that an acid R’COOH and an aldehyde RCHO could be isolated. Benzyl-2-chlorophenyl ketone, which is a liquid [Jenkins and Richardson, THIS JOURNAL, 55, 100 200 300 400 900 1618 (1933)l on standing slowly solidifies and RT loglo P,/P. acquires a strong odor of benzaldehyde. The Fig 2.---Potent ial-volume curves for the adsorption of nitrogen and argon on a single promoted iron synthetic solid is shaken up with dilute sodium carbonate solution and extracted with ether. The aqueous ammonia catalyst. layer is acidified with hydrochloric acid and 2The potential plots seem to represent the iso- chlorobenzoic acid is obtained. The ether is distherms very closely throughout the entire pressure tilled and the oil which remains is steam distilled. range covered, including: (a) the region concave The distillate is treated with phenylhydrazirw to the pressure axis where probably less than a acetate and benzalphenylhydrazone is obtained. molecular layer of gas exists, (b) the linear por- The solid gives a strong peroxide reaction using tion which we have postulated represents the the test of Kharasch [Kharasch, McNab and building up of a second layer of gas on the eat- Mayo, ibid., 55, 2523 (1933)l. aiyst surface [THIS JOURNAL, 57, 1754 (1935)], The course of the reaction may be illustrated as and (c) the higher pressure portion which is cm0 2 vex to the pressure axis and which, it is generally R’COCHzR +R’C(OH)=CHR + R’C(0H)-CHR +R’COOH RCHO believed, represents the condensation of the gas to liquid in the capillaries of the adsorbent. The O-----O inclusion of this last region in the portions repreThese reactions are being fully investigated sented by the potential theory is rather unexand the results will be reported later. pected since the theory was not intended to inSANFQBI) s. JENKINS THE CHEMISTRY DEPARTMENT OB clude such capillary condensations. THEJOHNS HOPKINSUNIVERSITY One other characteristic of the potential curves BALTIMORE, MARYLAND RECEIVED OCTOBER 24,1935 is worth noting. Polanyi and Gsldman found that for their data the adsorbed mass-potentid plots did n& coincide at different temperatures, the higher temperature curves being slightly be- CHBMICAL. STUDIES QN TOAD POISONS. VIII. THE DEHYDROGENATION OF CINOBUFAGIN low the lower temperature eurves in every ease. Sir: They explained this displacement by poddating In our investigation of the chernkl relationconstancy of adsorption volume and thermal expansion of the adsorbed gas, so that less gas was ship of the bufagins (cardiac principles present required to fill the adsorption volume at higher in toad secretions) to the cardiac plant aglucones, temperatures than a t lower. As shown in Fig. 2 possessing similar pharmacolcgieal and chemicai our potential climes exhibit no such variation properties, and to the sterols, it seemed of inA
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Vol. 57
terest to ascertain whether the bufagins, on 200-230’ was semi-crystalline and was fractiondehydrogenation with selenium, would yield ally recrystallized from alcohol according to the methylcyclopentenophenanthrene. The f6rma- triangle scheme. After numerous crystallization of this hydrocarbon, C1sH16,is generally con- tions a hydrocarbon fraction was secured which sidered a characteristic of the sterol ring system. melted at 120-121’ and showed a m. p. of 121Cinobufagint, C25H3206 [Jensen and Evans, J . 122’ when mixed with methylcyclopentenoBioE. Chem., 104, 307 (1934)l (the analytical data phenanthrene (m. p. 123-124’) prepared from obtained for cinobufagin and certain of its deriva- strophanthidin (Elderfield and Jacobs). Anal. tives would also agree with C26HS406[Crowfoot, (by Dr. Ing. A. Schoeller, Berlin-Schmargendorf, Chew. and lnd., 54, 568 (1935)]), was therefore Germany). Calcd. for C18Hl6: C, 93.05; H , subjected to dehydrogenation by the procedure of 6.95. Found: C , 92.81; H , 6.82. Diels [Diels, Gaedke and Koerding, A m . , 459, 1 The author is greatly indebted to Dr. W. A. (1927)l. As only a limited amount of material Jacobs, of the Rockefeller Institute for Medical was available for this study, and losses were in- Research, New York, for a sample of methylvolved in thLe separation of compounds closely re- cyclopentenophenanthrene, and would like also lated chemically, the quantity of the hydrocarbon to express his thanks to Dr. K. K. Chen, Lilly finally obtained was so small that a complete Research Laboratories, Indianapolis, for a supply characterization was impossible. From the mix- of an extract of Ch’an Su. ture of the reaction products about 10 mg. of a LABORATORY FOR ENDOCRINE RESEARCH H. JENSEN OF MEDICINE hydrocarbon fraction was secured which melted SCHOOL THEJOHNSHOPKXNS UNIVERSITY at 120-121’. This hydrocarbon is believed to be BALTIMORE, MD. RECEIVED NOVEMBER 22, 1935 identical with methylcyclopentenophenanthrene. Its analytical data agree with the formula C18Hls, and on mixing it with methylcyclopentenophenanthrene obtained by Elderfield and Jacobs [ J . THE COLLAPSE OF MONOMOLECULAR FILMS OF PALMITIC ACID UPON ACID SOLUTIONS Biol. Chem., 107, 143 (1934)l by dehydrogenation S i r : of strophanthidin, no melting point depression When monomolecular films of palmitic acid was observed. It appears, therefore, that cinobufagin and probably also the various other bufa- were compressed on very pure hydrochloric acid gins contain the same ring system as the cardiac or phosphate buffer solutions contained in a plant aglucones and the sterols. After complet- Langmuir film-pressure trough, in the range ing this work, a paper by Ikawa [ J . Pharm. SOC. 15-20’, it was noticed that after each increJapan, 55, 144 (German abstract), 748 (original ment of weight had been placed in the balance Japanese) (1935) ] appeared, in which he reports pan, and the barrier advanced to establish the isolation of the Diels hydrocarbon CI8H16 equilibrium, a slow shrinkage followed, the area, from the dehydrogenation mixture of $-bufotaline. however, finally attaining a value which was reIn this connection it might be mentioned that producible to a high degree. When the comWieland and Hesse [Ann., 517 22 (1935)l re- pression was carried out in this manner, with an cently have obtained a hydrocarbon from the attempt to obtain “equilibrium areas” a t every dehydrogenation mixture of bufotaline which point of the force-area curve, the films collapsed they believe to be identical with chrysene. at a pressure apparently connected with the Investigations are now in progress to determine, hydrogen-ion concentration (i. e., the films could in the bufagins, the exact nature of the side chain be compressed without limit when a definite which contains the lactone ring. pressure was reached, the value of which has Five grams of cinobufagin, dried at 110’ been called the “collapse pressure” in the literain vacuo, was mixed with 6 g. of selenium and ture). When the collapse pressure values were heated in a flask with a glass joint ascending tube plotted against PH values of the substrate (which for thirty-five hours a t 310-320’ and then for varied from PH 1 to PH 6) an S-shaped curve ten hours at 320-340’. The reaction mass was resulted, similar to the percentage neutralizaextracted with ether and the residue from evapo- tion curve in the case of a weak organic acid in ration of the solvent was subjected to fractional water solution. However, the mid-point of this distillation at 12 mm. The fraction distilling at curve was about pH 3, as cumpared to pH 5, the
