30
W. H. BAUER,J. FISHER, F. A. SCOTT AND S. E. WIBERLEY
created. This new site may have a greater or less aBnity for the inhibitor than the original site. A similar argument can be made for the affinity of the new site for the second substrate molecule. We have suggested that cyanide may inhibit catalase by reacting directly with the primary complex at a rate too slow to be detected during the brief transient phase of the kinetics. The rates at which azide, hydroxylamine and other monovalent anionsz3react with the primary complex are s u e ciently slow to be detected even during the steady state phase.6-8,12,13,20,24 Because of the slow rates of inhibition, it is very probable that the main inhibitory reaction is not a simple addition complex of primary complex and inhibitor but the electronic rearrangement (oxidation-reduction, perhaps) which occurs within the ternary complex subsequent t o its formation. This could result in a change in the bond type of the heme from essentially ionic to covalent in character.25 Presumably, the secondary complex described by Chance2 is spectrophotometric evidence for this covalent compound. However, the picture has been com(23) Recent studies by Chancez' indicate that the reactive species of both the inhibitors and the substrate are the undissociated acids rather than the anions. (24) R. F. Beers, Jr., and I. W.Sizer, Science, 180, 32 (1954). (25) H. Theorell and A. Ehrenberg, Arch. Biochem. Biophvs., 41, 422 (1952).
VOl. 59
plicated by the recent discovery of another inactive complex by Keilin and Hartree.2e There have as yet been no correlation studies between spectrophotometric properties of these inactive complexes and the inhibitory reactions between monovalent anions and the primary complex. Various aspects of this will be discussed in forthcoming p a p e r ~ . l ~ - ~ ' Should the main mechanism of inhibition of the primary complex be through the formation of a covalent structure, we would have to consider the following sequence of reactions If (j 1 6s + -++ &SI*
f
%I
Ka* = pi/q"*
(26)
where ESI" and ESI are the ionic and covalent complexes, respectively. The correct value of Ks is, therefore KB = (pi/Ks')/qr
(28)
Acknowledgments.-The author wishes to thank Dr. M. F. Morales and Prof. Irwin W. Sizer for their helpful suggestions in the preparation of this paper. (26) D. Keilin and E. F. Hartree, Biochem. J., 49, 88 (1951). (27) R. F. Beers, Jr., in preparation.
X-RAY DIFFRACTION STUDIES OF ALUMINUM SOAPS BYWALTERH. BAUER,JOSEPH FISHER, FREDERICK A. SCOTT AND STEPHEN E. WIBERLEY Catm'butim from the Walker Laboratory of Rensselaer Polyiechnic Institute, Troy, New York Received June d8, 1064
X-Ray diffraction patterns have been obtained for two series of aluminum soaps. The first series consisted of aluminum di-soaps made from the following fatty acids, caproic, enanthic, caprylic, pelargonic, capric, lauric, myristic, palmitic and stearic. The second series was prepared from lauric acid with varying fatty acid-aluminum ratios. In the first series the most prominent characteristic is the presence of two or more definite orders of a long spacing which is proportional linearly to the number of carbon atoms in the hydrocarbon chain. A second feature is the appearance of a diffuse halo between 4.2 and 5.2 A. units. In the second series, soaps having a fatty acid to aluminum ratio greater than that of the di-soap show sharp patterns and the presence of fatty acid lines while those below the di-soap show no new lines but less distinct patterns.
Introduction In view of the importance of aluminum soaps as gelling agents for hydrocarbons it is surprising that so little X-ray diffraction work is available on these compounds. Ross and co-workers1p2 have published X-ray diffraction data on aluminum dilaurate and aluminum distearate prepared by the addition of an aqueous solution of potassium laurate or stearate to a large excess of an aluminum chloride solution. The precipitates obtained were then extracted with boiling acetone to presumably form the corresponding di-soaps. These investigators reported the existence of free fatty acid spacings in the unextracted material. Mysels3 studied the X-ray diffraction patterns of Napalm (a mixture of aluminum di-soaps) and aluminum dilaurate. He found the patterns to be strikingly similar, but that the sharpness of the patterns differed markedly (1) 8. Ross and J. W. McBain. Oil and Soap. 2 8 , 214 (1946). (2) 8. S. Marsden, K. J. Mysels, G. H. Smith and S. Ross, J . A m . Oil Chemist8 SOC.,26, 454 (1948). (3) K.J. Mysela, Ind. Enu. Chem., 41, 1435 (1949).
depending upon the method of preparation. He also found that there was no indication in the Napalm pattern of the presence of an aluminum monosoap or any of the aluminum oxides. Because infrared absorption m e a ~ u r e m e n t s ~ ~ ~ on aluminum soaps made from different fatty acids and with varying fatty acid to aluminum ratios have been most helpful in establishing the structure and existence of the di-soaps as discrete chemical compounds, it was felt that X-ray diffraction studies on a similar series would also aid in further clarifying the structure of aluminum soaps. Experimental The fatty acids which are liquids at room temperature were purified by distillation and the neutralization equivalents were checked by titration. The purity of the solid acids used in this investigation has already been discussed6 as well as the preparation and analysis of the aluminum soaps, (4) W. W. Harple, 9. 24, 635 (1962).
E. Wiberley and W. H. Bauer, Anal. Chem.
(5) F. A. Scott, J. Goldenson, S. E. Wibcrley and W. H. Bauer, THIS JOURNAL. 68, F 1 (1954).
X-RAYDIFFRACTION OF ALUMINUM SOAPS
Jan., 1955
31
TABLE I1 COMPOSITION OF ALUMINUM LAURATE SOAPS r
Saniple Designation
L-4.01 L-2.89 L-2.60 L-2.03 L-1 .29
Exp.
Moles of acid/mole of A1 Extraqtable with isoootane
NaOH, %
wt. % A1
Predicted from NaOH Used
Based on A1 anal.
0 10 45
3.21 4.34 4.81 6.05 8.60
4.00 3.00 2.67 2.07 1.00
4.01 2.89 2.60 2.03 1.29
Excess
-25
100
1.8 0.87 0.58 0.05 0.00
BY dfl.
Remaining By AI anal.
2.21 2.02 2.02 1.98 1.29
2.01 1.94 1.94 1.85 1.24
chains are extended in the crystal. The regular increase in spacing of about 2 b.per additional carbon atom is similar to that exhibited by the fatty acid crystals. The diffuse halo in the region corresponding to the “side-spacings” between 4.2 and 5.2 A. indicates more random orientation in this dimension. The halo actually consists of two diffuse lines which are close to the ends of the halo. Results and Discussions The second series of soaps studied were prepared by precipitation of the soaps from sodium X-Ray diffraction patterns were obtained first for a series of aluminum di-soaps (ie., a fatty acid- laurate solutions containing excess sodium hydroxaluminum mole ratio of 2: 1) made from straight ide on addition of a solution of aluminum s ~ l f a t e . ~ ~ ~ chain fatty acids containing 6, 7, 8, 9, 10, 12, 14, 16 By control of the amount of sodium hydroxide, the and 18 carbon atoms. Table I contains the long ratio of moles of fatty acid to aluminum was conspacings for this series of aluminum di-soaps. The trolled. Table I1 lists the composition of these short spacings were identical for the complete series. soaps. All of the di-soaps showed two strogg lines correI I 1 1 sponding t o spacings of 3.90 gnd 7.8 A,, and a weak line giving a spacing of 3.00 A. A diffuse halo was found in egch case, corresponding to spacings from 4.2 to 5.2 A.
The X-ray diffraction measurements were made with a General Electric XRD-3 instrument using copper K, radiation with a nickel filter. In some instances chromium K, radiation was used. The soap samples were passed through a 100-mesh sieve and mounted on cellophane discs containing a hole slightly larger than the 0.010 mm. diameter pinhole collimator. The sample to film distance was 50 mm. in the case of the flat casette assembly. In the case of the circular camera the effective film diameter was 143.2 mm.
TABLE I INTERPLANAR SPACINGS(‘Id” VALUES) FOR ALUMINUM DI-SOAPS Soap
Aluminumdicaproate Aluminum dienanthate Aluminum dicaprylate Aluminum dipelargonate Aluminum dicaprate Aluminum dilaurate Aluminum dimyristate Aluminum dipalmitate Aluminum distearate
1st Order
15.2 17.9 20.5 22.3 25.5 29.5 32.0
... ...
Long spacing, A. 2nd 3rd Order Order
7.8 8.9 10.2 11.1 12.3 14.5 16.8 18.5 20.4
5.1 6.0 6.8 7.6 8.1 9.8 11.2 12.3 13.7
Av.
15.4 17.9 20.4 22.4 24.8 29.3 33.1 37.0 41.0
Figure 1is a plot of the long spacings of the fatty acids and the aluminum soaps and the silver salts prepared from these same fatty acids. The data for the fatty acids and silver salts are taken from a previous paper.5 The long spacings obtained for the fatty acids agree well with those obtained by Francis and Pipere for the crystalline form of the acids which they denote as the C-form. The long spacings obtained for the silver salts agree well with those obtained by Matthews, et aL7 It should be noted that the long spacings of the aluminum soaps and of the fatty acids are almost identical while those of the silver salts are considerably longer. Apparently the aluminum soaps are similar to the long chain acids, alcohols, esters, nhydrocarbons and ketones in that the hydrocarbon (0) F. Francis and S. H. Piper, J . Am. Chem. SOC.,61, 577 (1939). (7) F. W. Matthews, G . G. Warren and J. H. Rtichell, Anat. Chem. 22, 514 (1950).
6
IO NUMBER
14
OF CARBON Fig. 1.
18
I
ATOMS.
The X-ray diffraction patterns of these soaps showed the presence of lauric acid in samples L4.01, L-2.89 and L-2.60. Both the long spacings of the soap and acid were readily distinguishable, and the characteristic 4.13 A. spacing of lauric acid was very prominent in all these samples. Samples L2.03 and L-1.29 did not shorn any lines attributable to acid spacings. Samples L-4.01, L-2.89 and L-2.60 were estracted with cold isooctane at 0 to 5”. X-Ray diffraction patterns of the extracted samples no longer showed lines ascribable to fatty acid. Only the diffraction pattern of the di-soap appeared. These results confirm those of previous workers1S2,*and are in excellent agreement with the infrared interpretation.4 Evidently then, aluminum soaps prepared by an aqueous method having an analysis close to a tri(8) J. D. Gross, “Ph.D. Tllesis,” Rensselaer Polytec. Inst., June, 1049.
AUBREYP. ALTSHULLER
32
soap consist of mixtures of di-soap plus fatty acid. It was shown in Fig. 1 that the long spacings of the aluminum soaps and of the fatty acids are almost identical. This fact explains why the fatty acid co-precipitates so readily with aluminum soap molecules to form materials of graded ratio of fatty acid to aluminum. The X-ray diffraction pattern of soap L-1.29 showed no new spacings that could be attributed to either an aluminum mono-soap or to hydrated aluminum oxides. The diffraction pattern was considerably more diffuse than that of the di-soap
VOl. 59
L-2.03. This is a generally observed phenomenon. For any series of a single acid, as the acid to aluminum ratio increases, there is a sharpening of the diffraction pattern of the soap. Infrared studies on aluminum soaps containing a mole ratio of fatty acid to aluminum less than 2 show only bands attributable to aluminum di-soap and hydrated aluminum oxide. It is therefore concluded that aluminum mono-soaps are not present. Acknowledgment.-This study was conducted under contract between the Chemical Corps, U. S. Army, and Rensselaer Polytechnic Institute.
DIELECTRIC PROPERTIES OF SOME ALKENES BY AUBREYP. ALTSHULLER National Advisoru Committee for Aeronautics
Lewis Flight Propulsion Laboratory, Cleveland, bhio Received July 16, 1961
The dielectric constants of pentene-1, hexene-1, heptene-1, octene-1, 2-methylbutene-1, trans-hexene-3 and cyclohexene have been determined. The atomic polarizations of these compounds as well as cis-hexene-3 and the cis- and trans-isomers of octene-3, octene-4 and decene-5 have been calculated. The dipole moments of the polar alkenes have been calculated by means of the Onsager e uation and are compared w t h the available dipole momenta in the gaseous state. The relationship between the observed%pole moments and the bond moments in the alkenes is very briefly discussed.
Although the dielectric constants of several alkene-1 compounds have been determined,l the results obtained have been scattered and somewhat contradictory. Therefore, it seemed useful to determine the dielectric constants of highly purified samples of pentene-1, hexene-1, heptene-1 and octene-1 as representatives of the class H&=CHR. The dielectric constant of 2-methylbutene-1 was determined as a representative of compounds of the H2C=CR2 type. The dielectric constants of cyclohexene and trans-hexene-3 were also measured. The dielectric constants, refractive indices and densities of four cis- and four trans-alkenes have been determined elsewhereS2 The atomic polarizations, PA,of the four trans-alkenes were calculated. The dielectric constant of trans-hexene-3 was redetermined because the literature value2 gave an atomic polarization out of line with that of the three other trans-alkenes. An empirical relationship between P A and c, the number of carbon atoms, was derived from the data for the four trans-alkenes and used to calculate PAfor the four &alkenes2 and the six alkene-1 compounds measured in this investigation. The dipole moments of the ten polar alkenes were calculated by means of the Onsager equation. The bond moments which contribute to the overall molecular dipole moments are briefly discussed. Experimental Materials.-NBS samples of pentene-1, octene-1 of 99+% purity, and trans-hexene-3 were used. The 2methylbutene-1 was obtained from APIRP-45. Phillips Petroleum Co. samples of pentene-1 of 99+% purity and of research grade cyclohexene of 99.9+% purity were also used. The hexene-1 and heptene-1 used were prepared and (1) A. A. Maryott and E. R. Smith, "Table of Dielectria Constsnta of Pure Liquids." NBS Circular 514, 1951. (2) K. N. Campbell and L. T . Eby, J . Am. Chsm. Xoc., 63, 216, 2083 (1941). (3) 'L. Oneager, ibid., 68, 1486 (1938).
purified a t this Laboratory by fractional distillation of the products of the dehydration of the corresponding alcohols through Podbielniak columns. All of these materials were passed through silica gel columns before the measurements were made. Dielectric Constants.-The dielectric constants were obtained using an apparatus and cell previously d i s c ~ s s e d . ~ The volume of liquid in the dielectric constant cell was 25 ml. The accuracy of the measurements is estimated to be *0.2%. Refractive Indices.-The indices of refraction were measured at 20.0 i 0.1" with a Bausch and Lomb precision Abbe refractometer with an estimated accuracy of 10.0001 units.
Results and Discussion The refractive indices, T L ~ O D , and the dielectric constants, e20, measured in this investigation along with previous literature values of B are listed in Table I. TABLE I DIELECTRIC CONSTANTS AND REFRACTIVE INDICES OF SOME ALKENES ea0
Compound
n2QD
(20
(lit. values)
1.3714 2.017 2.100,* 1.92" Pentene-1 (NBS) Pentene-1 (Phillips) 1.3712 2.017 1.3878 2.051" Hexeiie-1 1.3996 2.071. 2.06" Heptene-1 1.4085 2.084 ... Octene-1 1.3775 2.180 2.197* 2-Methylbutene-1 brans-Hexene-3 1.3939 1.954 2.000d (25") 1.4461 2.220 2.220" (25") Cyclohexene Hexene-l, 680 = 2.035; heptene-1, EM = 2.057. Ref. 5. * F. Fairbrother, J . Chem. Soc., 1051 c Ref. 6. d Ref. 2. (1948).
...
(1
The two values previously reported5asfor the di(4) A. P. Altshuller, THISJOURNAL, 68, 392 (1964). (5) A. E. van Arkel, P. Meerburg and C. R . v. d. Handel, Rcc. trow chim.. 61, 767 (1942). (6) M. L. Sherrill, K. E. Mayer and G. F. Walter, J . Am. Cfism. Xoc., 66, 926 (1934).
