Nov., 1937
NOTES
2467
termediates. How far it is really applicable can the essential factors determining the equilibrium only be determined by further experiment. Nev- constants. ertheless, it is interesting to consider a few of the Summary possible consequences if we do assume that the The intermediate form of oxidation-reduction phenomenon is general. First, the scope of the of phenanthrenequinone-3-sulfonate may be pressemiquinone theory is considerably broadened. ent in two forms, as a semiquinone radical, or as Thus it may now be possible to treat, in a more a valence-saturated dimeric compound of the satisfactory manner than has hitherto been posradical. There is an equilibrium between the sible, systems where no intermediate form has four forms of the dye: the oxidized, the reduced, heen shown to exist. In the light of the present theory it is entirely possible that an intermediate and the two intermediate forms. According to form does exist, but that the maximum concentra- this equilibrium the existence of the dimer is tion of the radical is not great enough to raise the favored by increasing the total concentration of index potential beyond the limits of error. In the the dye. In alkaline solution the intermediate case presented here, the high value of the dimeriza- form is represented mainly by the radical even in tion constant enables us to recognize the intermedi- moderately concentrated solution, and practically ate form in acid solution, which scarcely would be entirely so a t the concentration of 0.001 144 and possible if there were no dimerization. Second, we below. In acid solution the radical exists in any have dealt only with homogeneous systems. It is case only in extremely small amounts. The disuggestive that under physiological conditions and meric form is just as scarce when the total concentration of the dye is low; but it may increase with biologically occurring oxidation-reduction very considerably if the total concentration of the systems, adsorption at interfaces, or combination dye is high. The values of the equilibrium conwith specific proteins or enzymes, may have a stants are similar influence as variation in concentration or at gH 4.6 a t gH 12 pH has in a simple and homogeneous system. 28.6 Finally, this theory removes the question which Semiquinone formation constant k = (‘IO-3 Dimer formation constant q = 230 2000 of the intermediate forms exists in any given Dimerization constant Y = 9 2 X lo* 70 case; for the radical and its polymer can exist a t all times in equilibrium, the constants of Increase of alkalinity not only increases the total which are determined by the substances in ques- intermediate form, but also the fraction of this tion and by the conditions of the surrounding which is in the form of a radical, medium. The resonance of the radical is one of hTEW YORK,N. P. RECEIVED SEPTEMBER 11, 1937
NOTES The Identity of Solancarpine with Solanine-s
ancarpidine should therefore be removed from the literature. BY LINDSAY H. BRIGGS This observation tends to confirm the formulas A comparison, by the method of mixed melting C44Hi6018N or C44”1iO19N for solanine-s and points, of “solancarpine” from Solanum xantho- C2~H4303Nfor solanidine-s6 with which the folcai.puml and solanine-s both from S. sodomueum2 lowing additional analyses6are also in agreement. and S. auriculatum3 as well as of the related Solanine-s ( e x S. sodomaeum): Calcd. for CuH,aOlsN. aglyco alkaloids and their derivatives has shown 2Hz0: C, 56.11; H, 8.39; N, 1.47. Found: C, 56.10, that the alkaloids from all three botanical sources 55.98; H, 8.64, 8.68; N, 1.83, 1.75. Solanidine-s ( e x S. sodomaeum) : Calcd. for C20H4303N: are i d e n t i ~ a l . ~The names solancarpine and sol(1) Saiyed and Kanga, Proc. Indian Acad. Sci., PA, 255 (1936). (2) Odd0 and Caronna, Ber., 69B,283 (1936), and earlier papers (3) Anderson and Briggs, J . Chem. Soc., 1036 (1937) (4) Cf Briggs, THISJOUHNAL, 69, 1404 (1937)
C, 74.82; H, 10.31; N, 3.35. Found: C, 75.18, 75.10; H, 10.51, 10.57; N, 3.32, 3.38. (5) Cf., however, Rochelmeyer, Arch. Phar?n., 276, 336 (1937) (6) Analyses by Dr.-Ing 4 . Schoeller.
2468
NOTES
VOl. 59
Solanidine-s (ex S. auriculatum) : Calcd. for CzsHra03N: melting a t 197.6' (U. S. P. Corrected). The hT,3.35. Found: N, 3.33. saponification of this acid also gave different Solanidine-s sulfate: Calcd. for C?eHaoOaN.HnSOa:N,
2.72. Found: N, 2.81. Solanidine-s hydriodide : N, 2.57. Found: N, 2.53.
results from those described by Bergghrdh.
Calcd. for C ~ B H ~ ~ O ~ N . H INo : explanation of these differences is submitted.
It is possible that the prolonged heating carried out by Bergghrdh is responsible for his failure to secure the barbituric acid in the usual way. It has been demonstrated6 that better yields of the barbituric acids result if the refluxing is brief. Even with brief refluxing the yield is poor (16.8%), SO that the two-day refluxing of Bergg%rdh would result in only negli'gible yields. DEPARTMENT O F CHEMXSTRl AUCKLANDUNIVERSITY COLLEGE The possibility of rearrangement of the triAUCKLAND, NEW ZEALAND RECEIVED S E P T ~ M B28, E R1937 phenyl group must also not be overlooked. The reactions given in detail in the experimental part have been checked by another worker.6 5-Triphenylmethylbarbituric Acid The triphenylmethylmalonic ester was prepared BY HAROLD W. COLES' by the use of the magnesio-malonic ester alcohol The statement is made by Bergghrdh2 that complex. Pharmacologicallylh the j-triphenylmethylbar5-triphenylmethylbarbituric acid could not be bituric acid was inactive. In rabbits, doses up prepared by the common procedure] namely, by to 1260 mg. per kg. orally, and up to 800 mg. per condensation of the respective malonic ester with kg. intravenously, produced no hypnotic effect. urea (in this instance, by heating a day or two on The animals with the high doses simply went the water-bath). He reports, however, that he into collapse and died. The toxicity is low. It succeeded3 in preparing this acid by melting towas recognized that monosubstituted barbituric gether a mixture of triphenylchloromethane and acids are regularly without useful activity and barbituric acid in a vacuum a t a bath temperature the 5-triphenylmethylbarbituric acid is, therefore, of 165'. The isolation of a yellowish-brown normal in this respect. Attempts to attach a substance, m. p. 274-275', difficultly soluble in second substituent to the 5-carbon atom failed. alcohol, is described. He identified this barbiExperimental Part turic acid by heating it with sodium hydroxide Preparation of the Triphenylmethylmalonic Ester. 9solution on a water-bath for three days and obThis malonic ester was prepared by employing the magtained triphenylpropionic acid (m. p. 175-176'). He made no mention of any crystalline material nesio-malonic ester of Lund.lo Magnesium shavings, 2.5 g. (one mole equivalent), were weighed out into a roundseparating out of the alkaline solution during bottomed Pyrex flask and were covered with one-half of the prolonged saponification. a mixture of 28 cc. of absolute alcohol and 16 g. (one mole In view of this report, it seems desirable to re- equivalent) of malonic ester (Eastman). Carbon tetracord the experiences of the author, which are chloride (0.5 cc.) was added t o the flask as catalyst. The completely at variance with those of Berggardh. reaction started a t once, and was controlled by immersiou ( 5 ) (a) Shonle, Keltch and Swanson. Tms JOUKXAI., 62, 2440 It was found4 that triphenylmethyl malonic ester (19.70); (b) Rosenberg, Kneeland and Skinner, ihid., 66, I33!1 (1934) (6) The author is indebted to Miss Mary Dodds for i his ntsiitanre. reacted appreciably (16.8% yield) with urea (7) (a) J,iind, IIansen and Voiyt, Kgl. 1)uiz. D'id. S r l s k . Xlolh.-fs\ after only four hours refluxing on the water-bath .Medd., 12, No. Y (Dec. 1933); (h) 1,1111~~,ihid, 13, Pio. 1R ( I W a ) , in the presence of sodium ethylate. The tri- (c) Lund, Her., 67, 935 (1U84). (8) The author is indebted to the Uiologicrl Laboratories of 13. I
