SURFACEFILMSOF CHLOROGENIN AND DERIVATIVES
July, 1938
Pheqylglycerosazone: m.p. 132"; reported'*6m. p. 133". Hydroxymethylglyoxime: m. P. 134- 135". Reported' m. p. 168". Anal. Calcd. for CsHa03Nt: N, 23.7, Found: N, 23.4. An aqueous solution of the dioxime gave a red color with cobalt acetate in the presence of sodium acetate. On careful addition of dilute sodium hydroxide to this solution a green base was precipitated.
[CONTRIBUTION FROM
THE
1629
Summary 1, The alcoholate of the trimer of hydroxypyruvic aldehyde was prepared free from sulfur derivatives. 2' The quinoxaline phenylosazoneJ and dioxime were prepared. RECEIVED FEBRUARY 28, 1938 BALTIMORE, MD.
DEPARTMENT OF CHEMISTRY, STANFORD UNIVERSITY ]
Saponins and Sapogenins. VI. Surface Films of Chlorogenin and Derivatives By C. R. NOLLER
In the last paper of this series' the tentative formulas, I and 11, based on chemical evidence, CHs \1
I
CsHsO
'"ll cr]
CsHsO
compressible films indicating that the molecules are tilted or lying flat a t low pressure^.^ Hence it was expected that if formula I1 is a possibility for chlorogenin, the molecules in surface a m s would lie flat a t low pressures and give a highly campressible film. The data plotted in curve I show that this is actually the case. The mole-
I CHs HO
\
/\ /\/
i
A / /-I
Ho/\'A I1
were proposed for chlorogenin. Formula I1 was favored because the ketodibasic acid obtained on oxidation did not appear to be either an ctor a &keto acid as would be required by formula I. The second hydroxyl group was assigned to position 12, since the diketone forms a dioxime which would not be expected if the hydroxyl group is a t position 11. Recent work on the surface films of structurally related compounds2 indicates that those molecules having one or two hydroxyl groups in the end-ring give incompressible films in which the molecules stand on end and occupy an area that is predicted by models of the compounds. Cholestanol-6 and A4~6-cholestenol-7 ($-cholesterol) having hydroxyl groups in the second ring give highly (1) iToller, THIS JOURNAL, 69, 1092 (1937) (2) Askew, Farmer and Kon, J Chem S O L ,1399 (1936)
40 80 120 Sq. A. per molecule. Fig. 1.-Pressure-area curves for surface films of: I, chlorogenin; 11, gitogenin; 111, chlorogenin diacetate; IV, diketone from chlorogenin. 0
c u l a occupy at low pressures an even larger area than +-cholesterol, the film being gaseous a t very low pressures. At higher pressures the curve appears as if it will coincide with that for gitogenin (3) Adam, Askew and Daaielli, fiachem. J., PO, 1786 (1935)
but contraction begins a t a pressure of abnut l 3 dyiies per ceiitinietcr aiid a l higher pr the film collapses. Llowever, it reinairis mobile as shown by dustirii. with talc, even a t 32 dvnes per centimeter. “lliedata for gitogenin (curve 11) were obtained iisiiig a sample kindly supplied to us several pears ago 1)y 1-h IY.A. Jacobs o f the Rockcfellei Institute for Medical Research. The value of 39.5 (2. ior thc area per molecule a t zero pressure i s itleiitical with that obtaiiied previously’ a i d served to check our technique and procedure. Evidently under pressure the molecules of chlorogenin call be made to stand 011 end and occupy ail area very close to that occupied by gitogeniii, thus furnishing additional evidence for the close relationship in the structure of these two compounds. Chlorogenin diac-etate gives a curve, 111, which is very similar to that for chlorogeiiiii except that the lower attraction of the acetate groups for water is manifesl iii the greater teiiitciicy to rc main in the gaseouq state arid the greater itistability of the closr packed film. The diketoue obtained by the cxidatiorr oi chlorogeniii (curvr 11”)show\ 1x1 ttmdt~iicyto form a c*losc‘packer1 film hut collapses at pressures of ahout ii dyiies per ceiitimeter. Experimental The surface pressures were measured on a Cenco Hydrophi1 Balance hv the general procedure developed by Adam and his cci-cvorkcrs.; The sol-
vent used was a mixture of eight parts by volume of purified cyclohexane and two parts of purified dioxaiie. From 0.01 to 0.02 g. of compound was weighed accurately into a tared glass-stoppered 25-cc. Erlenmeyer flask and dissolved in 10- 80 cc. of solvent with warming if necessary. After coolinq to room temperature the flask was stopp m d arid the weight of solvent determined. For placing the solution on the surface a 1-cc. prouiid-glass syringe was used, whose tip was drawti out and grouiid so that small drops would form and leave the pipet without wetting the outer surface of the tip. The tip was fitted with a small cap by means of a grouiid joint to prevent evaporation during the weighing of the syringe. The space between plunger and barrel of the syringe was sealed by a narrow band of glycerol. All films were spread on 0.02 N hydrochloric acid ‘rhe films were not examined for collapse with a dark ground illuminator3 but the phenomeiion ()f contraction was observed shortly before collapse R’BS obvious.
Summary Measurements oii surface films of chlorogeniu, chlorogenin diacetate and tlie diketo derivative are in agreement with the view that the two hydroxyl groups are in different rings in the molecule. They also confirm the close relationship in structure previously assumed to exist between chlorogeiiiii and gitogenin. %rA?\TFURD 17NIVFRSIIV,CALI[*
RECEIVED
MAY4, 1‘33h
Saponins and Sapogenins, VII. The Structure of the Side Chain of Chlorogenin BY F. M. MCAIILLAN
AND
C. K. NOLLER
In previous chemical investigations on the struc- (i formulated in the eyuatioii ture G f chlorogeniii,’ it has been assumed that the two unreactive oxygen atoms of chlorogenin are CHs in a side chain whose structure is similar to that -of the isomeric compound gitogenin and of other steroid sapogeniiis. This side chain is generally believed to consist of two tetrahydrofuran rings, the chief chemical evidence being the oxidation of tigogenin acetateZ to an acid and a lactone as \
(1) Koller, THISJOUXXAL, 69, 1092 (1937), 60, 162D (L9.18) 12) Tscheschr and Hagedorn Her 68, 1 4 1 % 2247 i l‘?,3*5) ~
A1 ()
+
