517
V O L U M E 27, N O . 4, A P R I L 1 9 5 5 Table 11. Powder Diffraction Data for Steroids (Continued) d, A.
I/Ii
d , A. I/Ii BILE ACIDS F2. Desoxycholic Acid 6 12.0 8 8.98 2 6.92 10 6.28 3 5.87 3 5.66 7 5.41 3 5.19 6 5.03 3 4.47 4 4.27 6 3.97 4 3.85 5 3.69 3 3.41 3 3.33 4 3.24 2 3.07 1 2.88 2 2.77 1 2.71 3 2.61 3 2.52 4 2.46 1 2.40 1 2.36 2 2.32 1 2.13 2 2.00 2 1.94 2 1.83
d , A.
1/11
F.
F1. Cholic Acid 11.4 9.83 7.94 7.06 6.78 6.49 6.19 5.93 5.74 5.37 5.16 4.94 4.75 4.45 4.24 4.00 3.82 3.69 3.56 3.43 3 31 3.19 3.11 3 02 2.87 2.72 2.64 2.56 2.51 2.46 2.41 2.35 2.24 2.19 2.13 2.06 1.99
6 3 6 2 9 9 1 1 10 2 3 2 3
8
2 5 2 4 4 1 2
3 1 1 1
2 1 4 2 2 2 2
? 1 1
F3.
Dehydrocholic Acid 15.1 5 4 12.9 11.9 2 10.3 5 9.61 4 1 7.83 6.86 1 6.39 4 5 5.93 5.66 10 5.26 7 4.96 7 4.76 1 4.62 3 4.47 6 4.25 5 4.15 6 3.97 4 2 3.84 3.63 2 4 3.45 3.32 3 4 3.18 3.03 3 2.95 3 2.67 2 2.65 2 2 2.57 2.46 2 2.41 1 2.35 2 2.29 1 2.23 2 2.13 2 2.07 2
mortar to a fineness of about 200 mesh. The powders were placed in thin wall plastic tubes of 0.01-mm. wall thickness and 0.2-mm. diameter ( 2 , 3 ) . The mounted samples were exposed to nickel filtered copper radiation produced a t 35 KVP and 20-ma. current for 5 hours in Norelco (North American Philips Co., Inc., Mount Vernon, N. Y . )of 114.59-mm. diameter, Debye-Scherrer cameras. The patterns (Figure 1 ) were recorded on Kodak No-Screen x-ray film, developed for 5 minutes a t 68’ F. in Kodak x-ray developer. Relative intensities ( I / Z l ) of the pattern lines (Table 11) were determined by visual estimation with the strongest line noted as 10. The d values are given in Angstrom units with the copper radiation weighted wavelength value of 1.5418 A. used as the basis of spacing calculations. The wider use of the x-ray method of analysis for organic compounds should supplement melting point determinations and the use of infrared absorption analysis ( 4 ) . A distinct advantage of this method is that very small quantities of sample are requiredone milligram is usually sufficient for an analysis. Visual comparison with standard diffraction patterns usually (Figure 1) has been found sufficient for identification of these steroids, without resort to d value calculation. LITERATURE CITED
(1) Bernal, J. D., Crowfoot, D., and Fankuchen, I., Trans. Roy. Soc. ( L o n d o n ) , 239A, 135 (1940). (2) Beu, K. E., Rev. Sei. Instr., 22,62 (1951). (3) Beu, K. E., and Claasen, H. H., Ibid., 19, 179 (1948).
(4) Dobriner, K., Katzenellenbogen, E. R., and Jones, R. K., “Infrared Absorption Spectra of Steroids,” Interscience, New York, 1953.
RECEIVEDfor review September 16. 1954.
Accepted December 6, 1954.
Infrared Spectra of Alkyl Hydroperoxides HOMER R. WILLIAMS and HARRY S. MOSHER Department of Chemistry, Stanford University, Stanford, Calif.
The infrared spectra of 17 alkyl hydroperoxides, both primary and secondary, have been recorded between 2 and 15 microns. In each case the hydroperoxide showed a characteristic but rather weak absorption in the region 11.4 to 11.8 microns, which has been previously correlated with the oxygen-oxygen stretching vibration. This is a region in which some of the corresponding alcohols also absorb and thus i t is not a unique means of characterizing the hydroperoxide. All primary and secondary alkyl hydroperoxides showed absorption in the 12.0- to 12.5-micron region. A most interesting alternating pattern is shown by normal alkyl hydroperoxides in this region; those which had an even number of carbon atoms (butyl through decyl) showed two maxima (at about 12.1 and 12.4 microns) while the odd-numbered members of the series showed a single maximum at about 12.3 microns.
S
TUDY of the infrared spectra of hydroperoxides has been hindered by lack of sufficient examples of pure members of
this class. The availability of many new primary and secondary alkyl hydroperoxides (9) has permitted a more extensive study than was previously possible ( 3 , 4,7 ) . I n the present study the infrared spectra of nine primary and eight secondary pure liquid alkyl hydroperoxides (9) were recorded in the range 2 to 15 microns. The spectra of the corresponding alcohols were taken in each case for comparison. The important featuree of these spectra are recorded in Tables I to IV and Figures 1 to 7 .
EXPERIMEYTAL
Materials. The spectra were taken in each case on analytically pure (determined by combustion) alkyl hydroperoxides made by the methods outlined previously (9). The samples were used soon after preparation and were stored in the dark and cold until ready for use. The determinations were made without solvent using both a 0.003-inch polyethylene spacer and a thinner film which resulted when no spacer was employed. The spectra for both thicknesses are represented in Figures 1, 2, 3,and 4. Spectral Determinations. All spectra Fere determined on the Perkin-Elmer double beam recording Model 21 infrared spectro-
Table 1. Wave Length of OH Stretching Band of Alkyl Hydroperoxides and Corresponding Alcohols R n-Propyl n-Butyl Isoamyl n-Amvl n-HeGyl n-Heptyl n-Octrl n-Nonyl n-Decyl sec-Butyl Cyclopentyl 2-Pentyl 3-Pentyl %Hexyl 3-Hexyl 2-Heptyl 2-Octyl &Butyl
R-OH, P
2.98 2 99 2.99 2 99 3 on 3.01 3.00 3.02 3.00 2.99 2.98 3.00 2.95 2.96 2.98 2.99 2.90 2.96
R-OOH.
Shift,
P
P
2.94 2.96 2 95 2.96 2 94 2.92 2.96 2.97 2.98 2.96 2.95 2.96 2 90 2.93 2.95 2 98 2.91 2.91
0.04
0.03 0.04 0.03 0.06 0.09 0.04 0.05
0.02 0.03 0.03 0.04 0.05 0.03 0.03 0.01 0.05 0.05
ANALYTICAL CHEMISTRY
518 photometer equipped with a rock salt prism. The instrument was operated a t the following settings: resolution 927; response, 1: 1; gain, 6; suppression, 1. I n several cases there was occasion to retake the spectra of a particular hydroperoxide (in two cases on a sample which had been stored for 10 months); in all these cases the spectra r e r e completely reproducihle.
mation vibration of the CHz- group (6). I n addition, all of the primary hydroperoxides shoived characterist,ic weak absorption maxima near 6.i2 and 6.98 microns-that is, this region was a singlet for the primary alcohol (column D, Table 11)but a triplet for the primary hj-droperoxide (columns A, B, and C, Table 11). As the homologous series was ascended these maxima near 6.72 and 6.98 microns hecame progressively less discrete until in the DISCUSS103 case of n-decyl, these were inflections on the main 6.80-micron The absorption in the region of 2 to 5.6 microns for the 16 band. This is shorn in Figure 5 . It seems 1ikel)-that secondary hydroperoxides was almost identical for both the alcohol and the bands which are present in the hydroperoxide but absent in the corresponding hvdroperoxide. I n e , ery case, however, the 0-H alcohol result from interactions of the hydrogen of the alpha stretching band of the hydroperoxide dppeared a t a slightly methylene group ivith the unsymmetrical hydroperoxy radical. shorter wave length than that for the corresponding alcohol, The secondary hydroperoxides and alcohols also absorbed a t or indicating a slight but appreciably greater hydrogen bonding in near 6.80 microns, but none exhibited the characteristic triplet the pure liquid state fur the alcohol. Milas and llageli ( 1 ) found absorption of the primary hydroperoxides. Accordingly this apthe reverse shift in several acetylenic hydroperoxides. The pears to be a definitive, although not very prominent, feature of wave lengths of the 0-H stretching band for both the hydrothe infrared spectra of the saturated primary alkyl hydroperoxides peroxide and the corresponding alcohol are compiled in Table I. studied. I n these compounds the only difference in structure is the re-411 of the spectra, except those of cyclopentyl hydroperoxide and cyclopentanol, showed absorption a t or near i . 2 0 microns placement of the -OH group with the -0OH group. The spectra of tert-butyl hvdroperoxide ( 7 ) are added to this and (columns E and G, Talile 11) Tvhich has been attributed to the subsequent tables for purposes of comparison. \vagging or rocking vibration of the CHZ- group ( 5 ) . I n addition All the hydroperoxides and alcohols absorbed moderately to this major band, all of the secondary hydroperoxides showed strongly near 6.80 and 7.2 microns, regions assigned to the defora somewhat weaker hand a t 7.40 to 7.50 microns (column F, Table 11, Figure 6). This absorption was absent in the spectra of the primary hydroTable 11. -4bsorption of Alkyl Hydroperoxides and Alcohols in the Region peroxide and thus this is a de6.7 to 7.5 Microns finitive characteristic of those Alkyl Hydroperoxides a41C0hol Hydroperoxide Alcohol secondary alkyl hydroperoxide Aa B Ca D E F b G Hb Group studies. 6.72 n-Propyl 6.82 6.93 6.83 7.20 7.20 6.72 6.81 n-Butyl 6.96 6.82 7.24 7 24 The absorption of cuniene 6.72 6,80 ... n-Amyl 6 96 6 80 7.23 7.23 h y d r o p e r o x i d e a t 9 to 10 6.80 6.72 Isoamyl 7.20 7.20 6 96 6 80, 7 0 7.28 7 28 6.96 ti 82 6.80 6.72 n-Hexyl 7.22 7.24 ... 7 44c microns has been attributed B.irW 6 81 7 44c 6.80 0.72 n-Heptyl 7.23 ... 7.24 6.74 7.24 6.56 6 82 ... 7.24 6.81 n-Octyl ... to the isopropyl group. As 6.82 6.74 n-Sonyl 7.25 ... 6.96 6.84 7.25 seen in Table 111, both the 6 746 8.82 7.24 7.14c 6 96b 6.81 7.21 n-Decyl a l c o h o 1s and hydroperoxides 2-Butyl 6.83 6.84 7.24 7.49 7.26 7 54 6.86 Cyolopentyl 6.94 ... ... 7.42 7.42 absorb in this region and 2-Pentyl 7.41 6.84 7.24 ... 6.83 7.25 there does not appear to be 3-Pentyl 6.81 7.39 6.82 7.20 7.44 7.23 %Hexyl 6.81 7.24 7.48 7.24 6.82 7 32 any particular absorption band 6.82 3-Hexyl 6.82 7.22 7.38 7 52 7.22 ... 6.84 2-Heptyl 6.84 7.25 ,.. 7.50 7.25 in this region which is ... 7.24 6.80 2-Octyl 6.80 7.46 7.23 uniquely characteristic of any 6.75 6.80 ... 6.76 t-ButyI ... 7.30 7.22 7.29 one of the classes of comI n almost every case these secondary bands in the triplet, columns -4 and C, or the doublet, column F. were weak. pounds studied. Absorption b These points were inflections only. These bands became progressively less discrete as homologous series was ascended. a t 9.26 to 9.i1 microns has C Very weak and scarcely discernible. been ascribed to the deformation frequencv of the OH group ( 2 ) . Table 111. .4bsorption Spectra in the Region of 8.7 to 9.7 Microns for .-ilky1 Alcohols absorb in the region Hydroperoxides and Corresponding .4lcohols between 8 and 10 microns and Alkyl Hydroperoxide W a r e Length, -4lcohol Wave Length, Alkyl P fi Zeiss and Tsutsui ( I O ) have Group A B c Dn E Fh 1 9) assigned B wave length of 9.30 n-Propyl 8 52 9 44 9 60 9 08 9.32,5.44 to 9 45 microns to the carbon8 86 9 40 9.76 8 98 n-Butyl 9.32 9 .53 8 94 9.72 n-Anivl 5.48 oxygen stretching vibration of 9 $52 Isoamj.1 9.8s 8 88 9.42 9.45 8 84 9 50 9.86 8 94 9.44 n-Hexyl 9 45 the saturated normal primary 8 86 9 46 9.i2 8 94 9.44 n-Heptyl alcohols mith the exception of 9 64 n-Octyl 8 88 8 94 9,46 9 4.5 9.88 n-h-onyl 8 87 5 56 5.88 8 '(3 9.46 9.45 mpthyl alcohol which absorbs n-Decyl 8 88 9 64 8 90 9.46 :it 9.i microns in this region. 2-Butyl 8.80-9.00d . . 8 62-9 0 2 d 9.72 9.69 -4 similar assignment of 8.95 8.80-8.94d 9.42 5.i0 8 72-8 98d 9.66 2-Pentyl 8.80-8.92d 9.66 ... 8 70-8 8 8 , 9 O C 5.60 3-Pentyl to 9.03 microns for the simple ... 9.66 9.33,9.64 Cycloprntyl s'.'72-s'.b'cd 9.48 5.82 8.71-8.9hd 4 04a 9.48,9.80 %Hexyl unbranched saturated second3-Hexyl 8.80-8.92d 9 64 9 03a 9.40 8.74-8.524 9.38.9.62 a r y alcohols r a s made. 8 74-8.56d 9.40 9 03a 8.74-8.98d !7.43,9.70 2-Heptyl 9 70 q 02a 2-Octyl 9.32 8.70-8.93d 9 60 8.72-8.96d 9.34,9.60 B r a n c h i n g , unsaturation on ... . . . 8.30 . . . 9.76 . . . 8 30 tert-Butyl 9 68 the alpha carbon, or a n Values for maxima obtained for secondary alcohols by Zeiss and Tsutsui (column F) do not coincide exactly with any reported here. Presumably they are the second peak of the doublet reported in column D with excrption aromatic ring on the alpha of cyclopentanol. carbon atom, was shown by b Column F reports values recorded in ( I O ) ; Zeiss and Tsutsui ( I O ) have assigned this band to C-0 stretching vibration of alcohols. Zeiss and Tsutsui to cause Not reported in ( I O ) . d Bands reported b y a dash are closely associated as a doublet. considerable shift of this characteristic band.
;;
I . .
519
V O L U M E 2 7 , N O , 4, A P R I L 1 9 5 5 Infrared Absorption by Alkyl Hydroperoxides in Region of 11.4 to 11.8 Microns
Table IV.
Alcohol Conflicting Absorption Wave Length,
Alkyl Hydroperoxide Wave Length,
Alkyl Group n-Propyl n-Butyl Isoamyl n-Amvl n-HeGyl n-Heptyl n-Octyl n-Yonyl n-Decyl 2-Butyl Cyclopentyl 2-Pentyl 3-Pentyl %Hexyl 3-Hexyl 2-Heptyl 2-Octyl tert-Butyl
M
M
11.57 11.73 11.52 11.64 11.52 11.67. 11.82 11.64 11.64 11.66 ll.6A 11.50 (weak) 11.58 11.55 11.48 11.51 11.75 11.53 11.28 (weak) 11.82 (strong)
11.64 11.79
11.52 11.40 11.86 11.70 11.68 11.85 11.86 11.86
This region of the spectra of the primary and secondary saturated alkyl hydroperoxides is tabulated in Table 111. It is seen that the band a t 9.32 to 9.46 microns for the normal primary alcohols has been more or less uniformly shifted to longer wave lengths (about 10 microns on the average) in the corresponding hydroperoxide. I n general, the band broadens as the molecular weight of the alkyl hydroperoxide increased.
\ A
I n the case of the secondary alkyl hydroperoxides the picture is not nearly so clear-cut. Zeiss and Tsutsui (IO) designate a band a t 9.02 to 9.05 microns as characteristic of the carbon-oxygen stretching band in unbranched secondary alcohols; their figures are given in column F in Table 111. The authors did not record this exact band but presume that the one found a t 8.88 to 9.02 microns was the same as reported by these workers. Kot as much care was taken x-ith the purification of the alcohols as with the purification of the hydroperoxides, nevertheless the alcohols were essentially pure and these differences are in excess of experimental error. I t d l be noted that both the alcohols and alkyl hydroperoxides absorb in the region 8.75 to 9.0 microns (column D, Table 111), with the exception of the cyclopentyl derivatives, and the region is not therefore very definitive for the secondary alkyl hydroperoxides. Considerable study and additional examples would be necessary before definite assignments could be made with any certainty in this region; accordingly, the values for the maxima in this region are recorded in Table I11 and in Figures 1, 2, 3, and 4 without further speculation. All of these saturated alkyl hydroperoxides absorbed in the region of 11.4 to 11.8 microns. Shreve ( 7 ) reported absorption in this region as resulting from vibration within the OOH group. The maxima in this region which are weak to medium in intensity are reported for the hydroperoxides in Table IV. Several of the alcohols also absorbed in this region and thus this is not an ideal
E-NONYL HYDROPEROXIDE
ISOAMYL HYDROPEROXIDE
'JL
1 1 n-DEtYL HYDROPEROXIDE
n.HEXYL HYDROPEROXIDE
6
7
8
9
IO
I1
12
13
14
6
7
8
9
IO
11
12
13
14
Figure 1. Infrared spectra of n-alkyl hydroperoxides, 6 to 14 microns
Figure 2. Infrared spectra of n-alkyl hydroperoxides, 6 to 14 microns
The top curve in each case was taken on a thin film without spacer while the bottom curve was taken with a 0.003-inch Spacer
The top curve in each case was taken on a thin film without spacer while the bottom curve was taken with a 0.003-inch spacer
1
520 I
I
I
I
I
I
I
2-BUTYL HYDROPEROXIDE
w*
A N A L Y T I C A L CHEMISTRY
1
2-HEXYL HYDROPEROXIDE
W
I
I
I
I
I
I
2-PENTYL
3-PENTYL
6
7
Figure 3.
8
9
10
11
I
3-HEXYL HYD
HYDROPEROXIDE
I
I
I
I
HYDROPEROXIDE
12
13
I
I
I
I
-HEPTYL HYDR
14
6
7
8
9
10
12
II
13
14
Infrared spectra of sec-alkyl hydroperoxides, 6 to 14 microns
Figure 4. Infrared spectra of sec-alkyl hydroperoxides, 6 to 14 microns
The top curve in each case was taken on a thin film without spacer while the bottom curve was taken with a 0.003-inch spacer
The top curve i n each case was taken on a thin film without 8 acer while the bottom curve was taken with a 0.003-inch spacer. '&e single curve for 2-hexyl hydroperoxide is with t h e 0.003 inch spacer
method of characterization. I n every case, however, the absorption curve of the hydroperoxide differed greatly from the corresponding alcohol and could serve as a reliable method for distinguishing between the two, Table IV lists these characteristic bands for the hydroperoxides in the region 11.4 to 11.8 microne
along with any conflicting absorption bands for the corresponding alcohol in this same region. All hydroperoxides showed absorption maxima in the region of 12.0 to 12.5 microns (Table V) ; in the case of the n-alkyl hydroperoxides an extremely interesting alternating pattern was apparent a8
L 6
1
7
e
MICRONS
Figure 3. Comparison of infrared spectra of the normal alkyl hydroperoxides, 6 to 8 microns
C
6
8
MICRONS
Figure 6. Comparison of infrared spectra of t h e secondary alkyl hydroperoxides, 6 to 8 microns
I
1
II
12
13
V
I4 MICRO
Figure 7. Comparison of infrared spectra of the normal alkyl hydroperoxides, 11 to 14 microns
521
V O L U M E 2 7 , NO. 4, A P R I L 1 9 5 5 Table V.
46
bon atom n-paraffinic hydrocarbons in the solid state, but these alternations were not distinguishable in the liquid state. These alternations in the solid n-paraffins (which are due to skeletal stretching modes) show the doublet for the odd carbon atom nparaffin and the singlet for the even carbon atom homologs whereas the reverse of this is true in the above case of the n-alkyl hydroperoxides.
46
ACKNOWLEDGMENT
42
The authors wish to thank the California Research Corp. for a grant which made these studies possible.
Infrared Absorption by Alkyl Hydroperoxides i n Region of 12.0 to 12.5 Microns Hydroperoxide n-Propyl n-Butyl n-Amyl n-Hexyl n-Heptyl n-Octyl n-Nonyl n De c y I
-
Wave Length, I.1
12.20 12 18,12 12 26 12.10,12 12 26 12 1 G , 1 2 12 26 12 18,12
45
shown in Figure 7. The hydroperoxides with an even number of carbons showed two maxima a t about 12.1 and 12.4 microns, while those with an odd number of carbons showed a single maximum a t about 12.3 microns. This is a very characteristic region for the normal hydroperoxide series and only in the case of n-octyl alcohol was there an interfering band with the alcohols and in this case it was very weak. This alternation in frequency must pertain to the hydroperoxide group since the liquid alcohols do not show this characteristic phenomena. KO other reports of such an alternation in the infrared spectra of a homologous series taken in the liquid state is known to the authors. Sinclair (8) oliserved no systematic variations in the spectra of a series of even and odd chain length aliphatic acids. An extensive study of hydrocarbons by Shcppard and Simpson (6) has shown a similar regular alternation of infrared frequencies for even and odd car-
LITERATURE CITED
(1) Milas, N. A., and Mageli, 0. L.,
(2) (3) (4) (5) (6)
(7)
(8)
(9) (IO)
J. Am. Chem. SOC.,75, 5970 (1953). Miller, F., in H. Gilman, “Organic Chemistry, an ildvanced Treatise,” Vol. 111, p. 143, Wiley, New York, 1953. Minkoff, A. J., Discussions Faraday SOC.,9, 320 (1950). Philpotts, A. R., and Thain, W., AKAL.CHEM.,24, 638 (1952). Randall, H., Fowler, R., Fuson, N., and Dangl, J., “Infrared Determination of Organic Structures,” Van Kostrand, New York, 1949. Sheppard, N., and Simpson, D. M., Quant. Reu., 7 , 31 (1953). Shreve, O., Heether, AI., Knight, H., and Swern, D., ANAL. CHEM.,23, 282 (1951). Sinclair, R. G., J . Am. Chem. SOC.,74, 2575 (1952). Williams, H. R., and Mosher, H. S., Zbid., 75, 2984, 2987, 3495 (1954). Zeiss, H., and Tsutsui, M., Ibid., 75, 897 (1953).
RECEIVED for
review July 23, 1954.
Accepted November 29, 1954
Effect of Concentration and Sorption upon Migration of Cations in Paper Electrochromatography TAKUYA R. SATO, WILLIAM
P. NORRIS,
Argonne N a t i o n a l Laboratory, Lemont,
and
HAROLD H. STRAIN
111.
This investigation was designed to test t h e ef€ect of concentration and sorption of cations upon their electrical migration through moist paper. Under t h e conditions employed i n electrochromatography and with zones of ions such as lead and bismuth, t h a t are readily sorbed by t h e paper, t h e rate of t h e electrical migration is least a t t h e lowest concentration and increases w-ith concentration, approaching a limit as t h e concentration of the ions i n t h e migrating zones approaches t h e ionic concentration of t h e background electrolytic solution in t h e paper. I n chromatographic tests based upon flow of t h e electrolytic solution through t h e paper, t h e migration of the zones of sorbed ions also increases with concentration. Consequently, the proportion of t h e ions sorbed by t h e paper m u s t decrease with increasing concentration; conversely, the proportion of t h e ions remaining nonsorbed in the solution m u s t increase with t h e increasing concentration. As t h e nonsorbed fraction of t h e ions should undergo faster electrical migration t h a n t h e sorbed fraction, t h e electrical migration of all the ions should be proportional to the fraction not sorbed and should increase with concentration. For the precise description of migration rates, migration sequences, and separability, t h e concentration and t h e sorbability of t h e migrating ions should be specified. The effect of concentration upon t h e electrochromatographic separation of radium from its principal radioactive daughters and from barium has been determined.
I
S PAPER electrochromatography, the separability of mix-
tures of various ions depends primarily upon the differential migration rates. These rates vary with many conditions such as the nature and concentration of the background electrolytic solution moistening the paper, the treatment and wetness of the paper, the temperature, and the magnitude of the electroosmotic effect ( 3 , Q, 6-8, 11, 14). Many ions, particularly those not sorbed by the paper, migrate a t a rate independent of their concentration, provided the concentration is less than that of the background electrolytic solution ( 7 ) . With zones of the mixture a t concentrations higher than that of the electrolytic solution, the migration decreases with increasing concentration. At the leading boundaries of the zones, however, the ions diluted by diffusion and convection migrate rapidly, producing long diffuse leading regions ( 7 ) . Certain ions have now been found to migrate very s l o ~ l yat low concentration, the rate of migration increasing with the concentration. With these ions a t the lowest detectable concentration (as with carrier-free, radioactive isotopes), the rate of migration increases until the concentration approaches that of the background electrolytic solution. Only at concentrations significantly higher than that of the electrolytic solution do the migrating zones form diffuse, leading regions. Separate chromatographic experiments with flow of solvent as the driving force have revealed a relationship between the sorbability of the ions by the paper and the rate of electrical migration. Ions such as phosphate migrate a t a rapid rate with flow of the solvent and are, therefore, not sorbed by the paper. These ions exhibit a uniform rate of electrical migration a t various
