drolysis of In(II1) under these conditions. A plot of log [t&i] us. ESppl. for the indium wave of Figure 1 yielded, under these conditions, a straight line with reciprocal slope of 0.020 volt in good agreement with theory (0.0197) for a 3-electron reduction; previous work (8, 12) consistently noted a larger reciprocal slope. The voltage intercept, after careful correction for iR drop and different salt bridge, was found to be -0.531 0.003 volt us. S.C.E. As might be expected for a complexing cation, the observed El,2 in equivalent chloride is more positive (less reducing) than the potentials reported previously for reduction in 0.1 and 1.OM chloride. Moreover, it is 8 mv. less reducing than the E1,2 reported by Schufle et al. for 0.01M HC1. Significantly, the observed El,* in equivalent chloride is considerably more positive than the value -0.573 volt us. S.C.E. reported by Schufle et al. for the so-called reversible, uncomplexed In(II1) wave in perchlorate supporting electrolyte, notwithstanding the fact that indium in equivalent chloride is most probably complexed to a small extent ( I ) . Thus, on the reasonable assumption that In(II1) in equivalent chloride and 0.1M KN03 is complexed either by hydroxide or chloride (or both) our observed value of -0.531 f 0.003 volt US. S.C.E. would, of course, be more negative us.
S.C.E. than the true
result, a t least in part, of (chloride) Eli2 of the “uncontamination of the test solutions. complexed” aquo In(II1) ion by a term (in the Heyrovskji-IlkoviE equation) involving the indium complexity conACKNOWLEDGMENT stant(s). One of the authors (E.D.M.) is Current-voltage experiments with grateful for the use of facilities provided careful exclusion of chloride have conby Princeton University and for finanfirmed the irreversibility of In(II1) cial support provided by Carter Prodreduction in acidified perchlorate meucts, Inc., for part of this work dium. Measurements of indium re(indium in perchlorate). duction in the presence of equivalent chloride have yielded a corrected E111 of LITERATURE CITED -0.531 f 0.003 volt us. S.C.E., which is 42 mv. more positive (less reducing) (1) Bjerrum, J., ed., “Stability Conthan the value reported by Schufle stants,” Vol. 11, Butterworths, London, 1958. et al. for the “reversible” reduction of ( 2 ) Cooper, W. C., Wright, M. M., indium in noncomplexing perchlorate ANAL.CHEM.22,1213 (1950). medium. On the basis of these experi(3) Cozzi, D., Vivarelli, S., 2. Elektromental results, and accepting the notion chem. 58,907 (1954). (4) Frumkin, A. N., Trans. Faraday SOC. that a reversibly reduced complexed 55, 156 (1959). metal ion reduces a t a more negative (5) Frumkin, A. N., Florianovitch, G. M., than the reversibly reduced, simple Dokladu Akad. Nauk S.S.S.R. 80, 907 metal ion, it is concluded that the dis(1951).” (6) Furman, N. H., Cooper, W. C., J . Am. sociation constants reported by Schufle Chem. SOC.72, 5667 (1950). et at. for the dichloro (1.5 to 3.3 X (7) Kolthoff, I. M., Lingane, J. J., 10-2) and tetrachloro (6 to 13) indic “Polarography,” Vols. I, 11, Interions cannot be correct. Indeed, as science, New York, 1952. (8)-Ljngane, J. J., Ph.D. dissertation, the indium system is not polarographbnlversitv of Minnesota. 1938:’ J . Am. ically reversible in noncomplexing supChem. So;. 61, 2099 (1939). porting electrolytes-i.e., El,z, Eoamnlrsm (9) MacNevin, W. M., Moorhead, E. D., (uncomplexed) are not obtainableIbid., 81,6382 (1959). (10) Moorhead, E. D., Ph.D. dissertation, the unambiguous determination of these Ohio State University, 1959. constants in a straightforward polaro(11) Moorhead, E. D., Furman, N. H., graphic manner is a t most very unlikely ANAL.CHEM.32, 1507 (1960). (12) Schufle. J. A.. Stubbs. M. F.. ( J J7 ) ’ @itman, K. E., J.‘Am. Chem. Soc. 73; Our observations strongly suggest 1013 (1951). that the reversible In(II1) wave obtained by Schufle et al. a t -0.573 RECEIVEDfor review July 10, 1961. volt in perchlorate medium was the Accepted November 28,1961.
Separation of Isopropyl Alcohol from Aliphatic Sulfides and Thiols by Gas Chromatography VINCENT J. FARRUGIA and CHARLES L. JARREAU Oronite Division, California Chemical Co., Belle Chasse, l a . A method is described for gasliquid partition chromatographic separation of isopropyl alcohol from a series of seven aliphatic thiols and three aliphatic sulfides utilizing a twocolumn technique. The relative retention time and the retention volume per gram of stationary phase are listed for each compound on a system of dual columns as well as for individual columns.
C
odorizing agents for odorless natural gases are composed primarily of low molecular weight mercaptans or sulfides. Isopropyl alcohol is sometimes added to these warning agents as a cloud point suppressant. OMMERCIAL
Previous analytical methods for separation of aliphatic sulfides, mercaptans, and alcohols were time-consuming and required combinations of distillation and spectroscopy to be effective. Gasliquid chromatography has been applied with much success in the separation and identification of sulfur compounds. There are now available many investigational reports for a variety of partitioning agents used as stationary phases for gas-liquid chromatographic separations of thiols, sulfides, and alcohols. Desty and Whyman (4) used a dual stationary phase technique with hexatriacontane and benzyldiphenyl on Celite 545 with nitrogen as carrier gas and reported retention times for seven sulfur compounds. Analysis of C4 to Ca thiols
was reported by Sunner, Karrman, and Sunden (9) and by Liberti and Cartoni ( 6 ) . Ryce and Bryce (7‘) describe optimum conditions for the use of tritolyl phosphate on Celite 545 with helium as eluent gas to separate sulfur compounds from methyl alcohol, ethyl alcohol, and hydrocarbons. Amberg ( I ) reported separation of CSto Ca thiols and sulfides using this stationary phase on firebrick with nitrogen as eluent gas. Coleman et al. (2) employed Dow Corning 550 silicone oil a n acidwashed firebrick and helium as the eluent gas to separate C3 to Cg sulfides and thiols. Spencer, Baumann, and Johnson (8) reported separation of C1to Ca thiols and sulfides using dinonyl phthalate on firebrick with helium as VOL. 34, NO, 2, FEBRUARY 1962
271
Table I.
Composition and Operating Conditions for Various Columns Employed
Solid support, (2-22 firebrick; weight ratio, liquid: solid, 1:3; temperature, 50" C. helium flow rate, 50 cc./min.; sample size, 50 pl. Column A B Cm Da E Columnblength and material, feet 10, A1 10, Cu 6, Cu 6, Cu 12, Cu TTP TTP Stationary liquid DNBP DC200 DNBP a Columns C and D were not run alone but rather together with column C exiting to column D in series prior to detection. Columns were spiraled with a radius of about 1.5 inches.
'
the carrier.
Karchmer (6) employed
&B'-iminodipropionitrile on Celite 545 and helium as the eluent gas to effect the separation of ethyl alcohol from CS to CI thiols. This paper reports the satisfactory resolution of isopropyl alcohol from mixtures of C1 to Cd sul6des and thiols using a dual stationary liquid phase, di-n-butyl phthalate and tritolyl phosphate each on C-22 firebrick. Also reported in this paper are comparative retention data for thiols and sulfides on firebrick columns with single stationary liquid phases of Dow Corning 200 silicone fluid, diin-butyl phthalate, and tritolyl phosphate.
Di-%-butyl phthalate (DNBP) was obtained from Eastman Organic Chemicals, white label, Dow Corning 200 silicone fluid was obtained from the Dow Corning Corp., tritolyl phosphate (Lindol, TTP) from the Celanese Corp., and oxybis-2-ethylbenzoate from Eastman Organic Chemicals, white label. Viscasil 60,000 silicone fluid was obtained from General Electric. All thiols and sulfides were white label Eastman Organic Chemicals. Isopropyl alcohol, analytical reagent grade, was obtained from the Baker Chemical Co. All compounds were used without further purification. The solid support used in all columns was Johns-Manville C-22 Silocel firebrick, 42/60 mesh size. PROCEDURE
APPARATUS AND REAGENTS
A Perkin-Elmer Model 154D Vapor Fractometer was used. Columns were composed of materials described in Table I and operated under conditions described therein. All flow rates were measured at the exit of the Fractometer by a soap film flowmeter.
Compound Methanethiol Ethanethiol 1-Propanethiol 2-Propanethiol 1-Butanethiol 2-Methyl-1-propanethiol 2-Methyl-2-propanethiol 2-Butanethiol Dimethyl sulfide Diethyl sulfide Methyl ethyl sulfide Tetrahydrothiophene Isopropyl alcohol Benzene n-PentaneC Aird n-Heptane
The solvent used for the preparation of columns containing DNBP, TTP, or oxybis-2-ethylbenzoate as the liquid phase was acetone, reagent grade, and benzene for the D C 200 column and 1: 1 part by volume diethyl ether and acetone for Viscasil. Column packings were made by hand-stirring a mixture
DISCUSSION OF RESULTS
Logarithmic plots of relative retention times, or volumes, for the tandem column C-D vs. the same parameter for the columns used in this investigation yielded straight lines of approximately the same slope but with displacement (to each other) along the axis used for relative retention values of these other columns. Therefore the method of identification of compounds suggested by Desty and Whyman (4) was applicable (Figure 1). Column C and D used in series afforded the best resolution as well as the most symmetrical peak for isopropyl alcohol under the operating conditions
Table II. Retention Data Column C and De Column B Column A Retentionb Retention Retention' vol. per vol. per vol. per Relative" gram of Relative gram of Relative gram of retention stationary retention stationary retention stationary time phase, ml./g. time phase, ml./g. time phase, ml./g. 0.781 24.8 14.7 0.301 32.5 0.853 2.742 86.1 51.4 1.049 105 2.757 7.600 238 212 4.340 278 7.297 4.568 143 81.8 1.670 164 4.315 70.52 644 ... ... 19.00 724 14.09 443 ... 501 13.15 5.890 185 2 : 330 114 210 5.520 ... ... ... ... 462 11.70 3.099 98.2 1.262 61.8 I19 3.131 16.80 533 ... ... 7.650 240 3 359 165 244 6.39% 5.020 157 ... ... ... ... 8.698 273 7.180 274 4.340 212 15.38 485 ... ... ... ... 1.000 38.1 1.000 49.0 1.000 31.4 0.164 6.25 0.116 5.71 0.210 6.58 ... ... 6.999 219 7.000 267
:
All r.r.t. corrected for column dead time. No correction for pressure drop across columns. e Standard for relative retention time. d According to Desty (9);gas used to determine column dead time and volume. * Retention time data represent total elution time from both columns in series. Combined weight of both liquids taken a~stationary phase weight.
272
of support, solvent, and liquid phase a t 90" to 100" C. with a stream of dry air directed on the fluid surface. When near dryness, the mixture was spread out on a piece of aluminum foil under a n infrared heat lamp for approximately 1 hour. Standard 1/4-inch 0.d. copper or aluminum tubing was then packed with this dried material in a uniform manner by tapping the column a t constant intervals while the solid was being added. Glass wool plugs about '/P inch thick were placed in both ends of the packed column as close to the ends as possible. Columns packed in this manner usually required about 1 hour to become stable with no elution of solvent. Samples of thiols, sulfides, and isopropyl alcohol were run individually and in synthetic mixtures to determine retention times. Table I1 lists relative retention times and retention volumes per gram of stationary phase.
ANALYTICAL CHEMISTRY
Column E Retention vol. per Relative gram of retention stationary time phase, ml./g, 0.785 16.9 3.500 75.4 13.21 285 4.955 107 6.000 ... 4.025 8,190
... 11.40 1.000 0.310 6.980
... 120
...
86.7
...
176
... 245 21.5 6.67 150
employed. However, this system did not effect the separation of l-propanethiol and methyl ethyl sulfide. Tests on known synthetic laboratory mixtures and commercial mixtures containing these thiols, sulfides, and isopropanol indicated t h a t the areas under the chromatograms are proportional to the weight per cent present with a n accuracy of the amount present. of about =t4yo Column -4, di-n-butyl phthalate, exhibited complete resolution of all thiols and sulfides in this investigation but did not effect resolution of isopropyl alcohol and 1-propanethiol. This column may be used with the same accuracy as the tandem column C-D for the measurement of isopropyl alcohol in mixtures not containing l-propanethiol. Column El, DC 200 silicone fluid, performance closely paralleled that of column .A with no resolution of 1-propanethiol and isopropyl alcohol peaks. Column E, tritolyl phosphate, did show some resolution of the isopropyl alcohol and the 1-propanethiol peaks but no quantitative separation of these two compounds. Ryce and Bryce ( 7 ) report excellent resolution of methyl and ethyl alcohol from their corresponding thiols on a TTP column with programmed temperature. Separation of methyl and ethyl alcohol from mivtures of these thiols and sulfides was effected on the columns used in this investigation also. Other columns used in this investigation were firebricks n ith Viscasil 60,000
Figure 1. Observed relative retention times of thiols on column C-D vs. columns A, B, and E Column A, Column E,
A.
Column B, 0 .
0
I
0
and oxybis-2-ethylbenaoate. These colUmnS showed poorer separation of thiols and sulfides under conditions of reasonable flow rates and temperatures. ACKNOWLEDGMENT
The authors thank W.W.Hanneman of the California Research Corp. for his technical assistance in this and related basic chromatographic techniques.
,
1
, , I
I
,
I
,
/
(2) Coleman, H. J., Thompson, C. J., i$'ard, C. C., Rail, H. T., CHBM. 30, 1592 (1958). (3) Desty, D. H,, xature 179,241 (1957). (4) Desty, D. H., Whyman, B. H. F., A N A L . CHEM. 29,320 (1957). ( 5 ) Karchmer, J. H., Ibid., 31, 1377 (1909). (6). Liberti, A,, Cartoni, G. P., Chim. e. znd*
399
821
(7) Ryce, 9. A., Bryce, W. A,, ASAL.
cHEY. 29, 925 (1957).
LITERATURE CITED
(8) Spencer, C. F., Baumann, F., Johnson, J. F., Ibid., 30, 1473 (19%). (9) Sunner, S., Karrman, K. J., Sunden, V., Mikrochim. Acta 1956, 1144.
(1) amberg, C. H., Can. J . Chena. 36, 590
RECEIVED for review August 8, 1961.
(1958).
Accepted Xovember 39, 1961.
Liquid-Liquid Partition Chromatography of Steroids Systematic Approach Relating Column to Paper Chromatography Using the R, Function PETER KABASAKALIAN and JOSEPH
M. TALMAGE
Chemical Research and Developmenf Division, Schering Corp., Bloomfield, N.
b A direct extension of R p data for steroids from paper to partition column chromatography has been made. The practical quantitative range of a series of Zaffaroni-type solvent systems has been described using the generalized R,), function previously reported.
L
partition column chromatography has been used estensively by steroid chemists to separate and isolate milligram to gram quantities of unknown compounds after all the simple methods of separation have IQUID-LIQUID
J,
failed. It would be most helpful to know the solvent system required for the separation and the volume in which the compound would be eluted from such a column. The first requisite can be fulfilled by the use of paper chromatography (4,6), while the second requisite necessitates the use of some function which would interrelate the solute mobilities in paper and column chromatography. Consden, Gordon, and Martin (S), who have considered paper chromatography to be simply a form of liquidliquid partition chromatography in which the filter paper acts as the inert
support of a stationary aqueous phase, have defined the quantity ( R F ) pfor paper chromatography as the ratio, v/V, of the distance traveled by the leading edge of the solute band to the distance traveled by the solvent (Figure 1). The quantity ( R F ) , for column chromatography (6) is defined as the ratio, v/V, of the rate of movement of the maximum concentration of a solute band down the column to the movement of the eluting solvent in the packed column. The measurement of the movement ( V em.) of the developing solvent in descending paper chromatography is started a t the top of the paper VOL. 34, N O . 2, FEBRUARY 1962
273
