between gas chromatography and phase solubility analysis was considered excellent. ACKNOWLEDGMENT
Certain phenols suspected of being impurities were prepared by T. H. Colby. The gas chromatographic apparatus was designed by F. M. Nelsen.
LITERATURE CITED
(1) Brooks, V. T., Chem. Znd. (London) 105Q.o.1317. .C
(2)-DUvall, A. H., Tully, W. F., J .
Chromatog. 11, 38 (1963). (3) Freedman, R. W., & Charlier, G. O., ANAL.CHEM.36, 1880 (1964). (4) Gill, H. H., Zbid., p. 1201. (5) Grant, D. W., Vaughan, G. A., in
“Gas Chromatography,” M. van Swaay, ed., p. 305. Butterworths, London, 1962.
(6) Mader, W. J., “Organic Analysis,” J. Mitchell, Jr., ed., Vol. 11, p. 253, Interscience, New York, 1954. (7) Porcaro, P. J., ANAL.CHEM.36, 1664 (1964). (8) Tominaga, Sachiyuki, Bunseki Ka aku 12, 137 (1963); Lowry Abstract &rd 37, 6-15-63.
RECEIVEDfor review March 7, 1966. Accepted June 6, 1966.
Identification of Normal Paraffins, Olefins, Ketones, and Nitriles from Colorado Shale Oil TAKE0 IIDA, EllCHl YOSHII,’ and EITARO KlTATSUJl Faculty of Pharmaceutical Sciences, Toyama University, loyama, lapan Straight-chain components of a Colorado shale oil distillate boiling from 280” to 305’ C. were obtained through urea adduct formation, and analyzed principally b y chromatographicseparation methods. They were found to be a mixture of paraffins (C13 to CIS), olefins (c13 to CIS) with predominantly 1-alkenes, nitriles (CIZ to Cia), and ketones (C13 to GIB) in which 2-alkanones are predominant. A useful and convenient chromatographic method for the separation of hydrocarbon components uses a silica gel-silver nitrate mixture. A mixture of ketones and nitriles is most effectively separated b y sodium borohydride reduction followed b y adsorption chromatography.
I CRUDE I
SHALE OIL1
1
GAS O I L ( C u t 4 ) B . p . 2 8 O o - 3 0 5 e C.
E x t r a c t i o n w i t h 5% KOH I
I
TAR BASE E x t r a c t i o n w i t h 60% H 2 g 0 4 I
r
60%
NEUTRAL O I L
91% of o r i g i n a l gas o i l
oil is a complex mixture of saturated, olefinic, and aromatic hydrocarbons, as well as nitrogen-, oxygen-, and sulfur-containing compounds. The nonhydrocarbon constituents that make up approximately half of the shale oil are an outstanding characteristic of shale oil as compared to petroleum. It is important to know the types of these compounds and desirable to determine the structures of individual components, not only in connection with processing techniques for fuel oil production but also the use of byproducts with industrial raw materials. U. S. Bureau of Mines workers (14) and others (6, 6, 9-12) have made valuable contributions to the identification of the shale oil naphtha components consisting of tar bases, tar acids, neutral nitrogen and oxygen compounds, and hydrocarbons. However, high boiling fractions which constitute a major portion
D i l u t i o n w i t h H2g
HALE
address, Department of Chem2yPresent, Columbia University, New York, 1
1224
ANALYTICAL CHEMISTRY
SOLUBLE
I
Urea Adduct Formation
S
n2s04
COMPOUND
I
BRANCHED-CHAIN NEUTRAL OIL
STRAIGHT-CHAIN NEUTRAL O I L
80% Adsorption Using S i l i c a Gel
T PARAFFIN-QLEFIN MIXTURE, C12-C19
9%
I P r e p a r a t i v e S c a l e GLC
MIXTURE, 2%
I NaBH Reduction -4
I
A d s o r p t i o n U s i n g Silica G e l
Cr03 O x i d a t i o n
Figure 1.
Separation of groups of compounds from shale oil
of shale oil distillate have not been so extensively investigated. The type analyses of individual concentrates separated according to physical prop-
erties have been principally carried out (2-4). In 1956, one of the present authors (T. I.) began to study the components
Table 1.
Boiling Points and Yields of Shale Oil Fractions
Cut no.
B.p., "C. . . . 215
1
3000
2000
1000
1500
Infrared spectrum of straight-chain paraffin and olefin mixture from
\I
1160
5000
3000
2000
700
1000
1500 WAVENUMBER (cm+ )
Figure 3.
Infrared spectrum of straight-chain ketone and nitrile mixture from cut 4
of Colorado shale oil under a cooperative agreement between the U. S. Bureau of Mines and Toyama University. He discovered in a heavy oil fraction the presence of a class of middle layer base which consists largely of long-chain 2,4,&trialkylpyridines (8). The present work is concerned with the constituents of neutral straight-chain compounds obtained from the distillate boiling from 280' to 305' C. Specific emphasis was placed on the separation and identification of an olefin mixture and a ketone-nitrile mixture. The result could be applicable to other fractions of shale oil distillate as well as related oils.
5.3 5.5 5.6 5.6 5.7 5.7 61.0
250-80 280-305 305-25 325-50 350-70
of compounds are schematically outlined in Figure 1. Reagents. Silica gel impregnated with silver nitrate for elution column chromatography was prepared by thoroughly mixing 40 grams of silica gel (Merck, 0.2 to 0.5 mm.) and 8 grams of Soy0 aqueous silver nitrate, followed by drying in the dark a t 120' C. for 4 hours (16). Thin-layer plates of silica gel-silver nitrate were prepared by spraying the usual 250-micron layer of kieselguhr G (Merck) with 20% aqueous silver nitrate, followed by reactivation at 110" C. for 10 to 15 minutes. The developing solvent system used for the separation of hydrocarbons was a n-hexane-benzene mixture (20 to 1). Spots were detected by spraying 60% sulfuric acid and heating a t 100' to 150' C., when dark spots appeared, or by spraying a 0.2% ethanolic solution of fluorescein sodium, when yellow spots were observed on an orange-red background under visible light or yellow fluorescent spots under ultraviolet light (1). Apparatus. For preparative scale gas-liquid chromatography (GLC) a Beckman Megachrom instrument with eight 6-foot columns in parallel was used. The column packing was 7% methyl silicone polymer (SE-30) coated on 40- to 60-mesh Microsorb F. The temperature range was from 193' to 203' C. For the analytical GLC, a Shimazu Model GC-1B instrument was used in conjunction with a hydrogen
700
WAVENUMBER (cm-l)
Figure 2. cut 4
6.6
iii-50-
2 3 4 5 6 7 Residue 5000
Yield based on crude oil, %
This oil was successively washed with 5% aqueous potassium hydroxide, 30% sulfuric acid, and 60% sulfuric acid to remove tar acids, tar bases, and "green oil" probably containing pyrroles (positive Ehrich test) (9). The neutral oil thus obtained was resolved into straightchain and branched-chain compounds through a urea complex formation technique. Further separations of groups
EXPERIMENTAL
Preparation of Starting Material. Crude shale oil obtained from Colorado oil shale by N-T-U retort at the Rifle plant (7, IS) was separated into seven fractions by fractional distillation under reduced pressure. Boiling ranges corrected to 760 mm. of Hg as well as yields of each fraction are given in Table I.
I
0
The work discussed in the present paper was done on the cut 4 gas oil boiling in the range from 280" to 305' C.
8
16
24
32
I
40
RETENTION TIME(min.1 Figure 4.
Gas chromatogram of straight-chain hydrocarbon from cut 4 VOL. 38, NO. 9, AUGUST 1966
1225
from which original ketones were recovered by oxidation with chromic acid in acetic acid. Chain length distribution of the ketone mixture was determined by converting into the corresponding paraffins by the Huang Minlon reduction method, followed by GLC analysis. For the estimation of carbonyl group distribution in the chain, the sample was fractionated by preparative scale GLC and then Schmidt reaction was applied to each fraction.
Tetradecanate
Tridecanate
0
8
16
32
40
R E T E N T I O N TIME (rnin. )
1226
ANALYTICAL CHEMISTRY
HiSOi
HC1
Figure 5. Gas chromatogram of carboxylic acid methyl esters obtained from straight-chain Cla nonterminal olefins
flame detector. Dual columns, 4 mm. in diameter and 150 cm. in length packed with 27, SE30 on silanized Chromosorb W, were generally used with a temperature program of 2' C. per minute. Infrared spectra were taken by HitachiPerkin Elmer Model 125 and Nippon Bunko IR-S spectrophotometers. All data were obtained on thin film. Procedure. The sample was first separated by elution column chromatography using silica gel into hydrocarbon and a ketone-nitrile mixture. The former concentrate was obtained by elution with n-hexane and the latter with a n-hexane-benzene mixture (4 t o 1). Infrared spectra of both fractions are shown in Figures 2 and 3. HYDROCARBON. TLC (silica gelsilver nitrate) showed three spots, assigned by infrared spectra to be, in order of R,, paraffin, nonterminal olefin, and terminal olefin. Analytical GLC is shown in Figure 4. Each peak, which consists of hydrocarbon of the same carbon number, was fractionated by preparative scale GLC and subjected to silica gel-silver nitrate chromatography. The amount of paraffin, terminal olefin, and nonterminal olefin was obtained by direct weighing of the concentrates. The double bond distribution in nonterminal olefin was estimated by ozonolysis followed by QLC analysis of the derived carboxylic esters. A typical GLC result on CIS nonterminal olefins is given in Figure 5. NITRILEAND KETONE. The hydrocarbon-free nitrile-ketone mixture was reduced with a methanolic solution of sodium borohydride, and the resulting nitrile-secondary alcohol mixture was subjected to elution chromatography over silica gel. Elution with a nhexane-benzene mixture (4 to 1) gave nitriles which were characterized by infrared spectrum (Figure 6) and also by sulfuric acid hydrolysis to amides. Chain length was determined by analytical GLC (Figure 7). Further elution of the column with benzene afforded secondary alcohols,
__f
__$
24
Table II.
R-NH-CO-R' R-CO-NH-R' R-NHz, R-COOH, R'-NHz R'-COOH
"8
R-CO-R'
Dodecanate
An example carried out on C15 ketones fraction is given. Pentadecanones were treated with sodium azide in the presence of sulfuric acid, and the resulting amides were hydrolyzed by concentrated hydrochloric
Determination of Major Normal Hydrocarbon Fractions Obtained from Cut 4 Oil
Fraction Cl6
Alkane, %
1-Alkene, %
%Alkene, % '
65 67
30 25
3.5 3.8
c 1 7
Other alkenes, %
... ...
1.5
1.0
I
I
5000
3000
Figure 6. I
L
2000
1500 WAVENUMBER ( c m ~ l )
700
1000
Infrared spectrum of straight-chain nitriles from cut 4
I\
r
I
0
Figure 7.
I
8
16
24
RETENTION
TIME(min.1
32
40
Gas chromatogram of straight-chain nitriles separated from cut 4
acid in a sealed tube a t 200’ C. for 6 hours. After the usual workup, carboxylic acids were analyzed by GLC as methyl ester and primary amine as trifluoroacetamide. Tetradecanoic acid was found to be a major constituent in the acidic product. In the basic fraction CI3 amine was predominantly found.
1635
960
RESULTS AND DISCUSSION
Hydrocarbons. I n the investigation of the hydrocarbon components of shale oil distillate, elution adsorption chromatography using silica gel has been successfully applied for the separation of paraffin from olefin (3). Further separation of isomeric olefins by this method, however, is almost impossible. The present work has shown that silica gel impregnated with silver nitrate is a useful adsorbent for the type analysis of shale oil hydrocarbons. Paraffin, terminal olefin, and nonterminal olefins were completely separated from each other on TLC as well as by elution chromatography. Among olefins, the terminal one was most strongly adsorbed; as the double bond goes to the center of the chain, it was less strongly adsorbed. Olefin concentrates were easily characterized by infrared spectra: terminal olefins a t 910 and 990 cm.-l (deformation bands) and 1635 cm.-1 (stretching band) ; nonterminal olefins a t 960 cm.-’ (deformation band). Analytical results on CI6and C17 hydrocarbons are given in Table 11. A noticeable fact about the straight-chain olefinic components is that double bond distribution is strongly favored toward the end of the chain. The same situation would be expected in fractions of both higher and lower boiling point. Nitriles. Separation of the ketonenitrile mixture into each functional component by elution adsorption chromatography was not practical because of their close polarities against various kinds of adsorbents. However, selective reduction of ketonic compounds with sodium borohydride to the corresponding secondary alcohols made it possible to isolate nitriles by silica gel chromatography. Whether or not the shale oil distillate contains aliphatic nitrile has been questioned (14). As a matter of fact, it is impossible to find in the infrared spectrum of the distillate the characteristic stretching vibration band of nitrile. As shown in Figure 8, only strong ketone (1700 crn.-l) and double bond absorption bands (1635, 990, 960, and 910 crn.-l) are observed. The present investigation confirmed the presence of nitriles of Clzthrough CISin the distillate
910
5000
3000
2000
1000
1500
700
WAVENUMBER (=my1
Figure 8.
infrared spectrum of straight-chain neutral oil from cut 4
boiling from 280’ to 305’ C., although in small amount (0.2%). Ketones. Alkanones of C13 through Cls were identified. The Schmidt reaction method which was used for the estimation of carbonyl position distribution is not necessarily the best method. There is no definit evidence about the side of the carbonyl group to which the imino group is preferably introduced in the case of the long-chain ketone. However, degradation experiments on fractions of the same carbon number showed that one carbon less carboxylic acid and two carbon less amine were predominantly formed. This suggests that 2-alkanone is the major component in the shale oil distillate of the present investigation. ACKNOWLEDGMENT
The authors are grateful to E. Ochiai for his encouragement throughout this work, and to K. Mitsuhashi of Toyama University for his helpful suggestions. They also express their thanks to M. Ishikawa and T. Tsuchiya, Tokyo Medical and Dental Cniversity, for carrying out preparative scale gasliquid chromatography, to C. H. Prien, Denver University, and B. Guthrie, U. S. Bureau of Mines, for their kind supply of Colorado shale oil, and to Idemitsukosan Co., Ltd., for the transportation of shale oil. LITERATURE CITED
(1) Barrett, C. B., Dallas, M. S. J., Padley, F. B., Chem. Ind. (London) 1962, 1050. (2) Dinneen, G. U., Cook, G. L., Jensen, H. B., ANAL.CHEM.30 2026 (1958). (3) Dinneen, G. U., Smkh, J. R., Van Meter, R., Allbright, C. S., Anthoney, W. R.. Ibid.. 27. 185 (1955). (4) Eisen, 0.; Goryuch, S., Khim. i Tekhnol. 1961, 213.
(5)Eisen, O.,Rang, S. A,, Ibid., 1961, No.4, 200. (6) Eisen, O., Rang, S. A., Arumeel, E. K.. Kim. i Tekhnol. Tovliu i Mosel 8. 38 (1963). (7)‘Hull, W.’ Q., Guthrie, B., Sipprelle, E. M., Ind. Eng. Chem. 43, 2 (1951). (8) Iida, T., J. Pharm. SOC. Japan 82, 144, 151 (1962). (9) Iida, T., Pharm. Bull. 1, 209 (1953). (10) Iida. T.. Tanaka. M.. J. Pharm. SOC. . iapan,’64,’162(1944). ’ (11) Iida, T.,Tanaka, M., Pharm. Bull. 1, 211 (1953). (12) Klesment, I. R., Eesti NSV Teaduste Akad. Toimetised 13, 297 (1964). (13) Ruark, J. R.,Berry, K. L., Guthrie, B.. U. S. Bur. Mines Revt. Invest. 5279 (1956). (14) Van Meter, R., Bailey, C. W., Smith, J. R., Moore, R. T., Allbright, C. S., Jacobson, I. A,, Hylton, V. M., Ball,’ J. S.. ANAL. &EM. 24. 1758 (1952). (15) Wagner H.,Goetschel, J. D., Lesch, P., Helu. dhim. Acta 46, 2986 (1963). \ - - - - ,
RECEIVED for review March 10, 1966. Accepted June 10,1966. Work su ported by a grant from the Ministry of Eication of Japan.
Correction Estimation of Medium Effects for Single Ions and Their Role in the Interpretation of Nonaqueous pH I n this article by Orest Popovych
(ANAL. CHEM. 38, 558 (1966)], the e. m. f. of the cell described on page 559 below Equation 9 should be equal to (Ej- k logmYH). In the title of Table I11 on page 561, the scale should read “molal,” instead of “molar. ”
VOL. 38, NO. 9, AUGUST 1966
1227
