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INDUSTRIAL A N D ENGINEERING CHEMISTRY
3-Beilstein and Kurbatow, Ber., 13, 2028 (1880). 4-Mabery, Proc. A m . Acad. Arts Sci., 81, 10 (1895). 5-Coates and Best, J . A m . Chem. SOC., 2s. 1155 (19031. ti-Marcusson, Milt. kgl. Materialgrtlfungsamt, S1, 301. 7-Mabery, J . Ind. Eng. Chem., 6, 101 (1914). &Coates, J. A m . Chem. Soc., 28, 384 (1906). 9-Warren, Proc. A m . Acad. Arts Sci., 21, 56 (1891); 34, 92 (1898). IO-Young and Thomas, J. Chem. SOC. (London), ‘71, 440 (1897); Young, Ibid., 73, 905, 920 (1998). 11-Young, Chem. News, 71, 177 (1895). 1.2-Bushong, J . Ind. Eng. Chem., 6, 888 (1914). la-Evans, J . SOC. Chem. I n d . , S8, 401T (1919). 14-Reed and Williams, Ibid., 88, 319T (1919); 39, 289T (1920). 15-Anderson and Erskine, I n d . Eng. Chem., 16,263 (1924). l&Leslie, “Motor Fuels,” 1923, p. 114. Chemical Catalog Co. 17-Duftor1, J . SOC.Chem. Ind., 88, 461’ (1919).
Vol. 18, s o . 7
18-Fortey. J . Chem. SOC.(London), 13, 932, 949 (1898). 19-Warren, Mem. A m . Acad., 9, 135 (1867). 20-Thorpe and Jones, J . Chem. SOC.(London), 63, 290 (1893). 21-Mabery and Hudson, Proc. A m . Acad. Arts Sci., 82, 101 (1896). 22--Richter, “Organische Chemie,” 11th ed., 1909, Aufl. I, p. 90. 23-Chavanne and Simon, Comfit. rend., 166, 1324 (1919). 24-Mabery and Young, J. Franklin Inst., 162, 57, 81 (1907). 25--MarkownikotT, B n . , SO, 975 (1897). 26-Zelinsky, Ibid., 40, 4743 (1907). 27-Risseghem, Bull. SOC. chim. Belg., SO,8 (1921). 28--Redwood, “A Treatise on Petroleum,” 3rd ed., 1918, Vol. I, p. 242. Pg-Kymer, J . grakt. Chem., 64, 126. 30--Thorpe, J . Chem. SOC.(London),87, 73 (1880). 31-Clarke, J. A m . Chem. Soc.. 88, 520 (1911). 32-Lemoine, Bull. SOC. chim., 41, 163 (1884). 33-Young and Richardson, J . Franklin I n s t . , 41, 50.
The Aromatic Hydrocarbon Content of Natural Gas Gasoline’ By A. M. Erskine HAMILTON COLLEGE, CLINTON, N. Y.
N T H E study of the com-
were not successful owing to The presence of small amounts of benzene, toluene, position of natural gas the difficulty of salting out and m-xylene in a sample of Pennsylvania absorption gasoline by Anderson and the very small amounts of the natural gas gasoline has been proved by fractionation, Erskine12the specific gravitysulfonates . concentration of each aromatic hydrocarbon by exboiling point curves for the Direct nitration of portions traction with liquid sulfur dioxide, and identification first, third, and fifth prelimiof the crude gasoline fractions as the corresponding dinitro or trinitro derivative. nary fractionations showed by mixed acid was also tried. Quantitative determinations on the fractions using marked and progressive inWhile nitro products were obthe nitrobenzene critical solution temperature method creases of specific gravity in tained which appeared to be showed that the original sample contained 0.6 per cent the ranges 75” to 95” C. and m-dinitrobenzene a n d 2 ,4benzene, 0.6 per cent toluene, and 1.2 per cent m-xylene 100” to 120’ C., indicating dinitrotoluene from the corby weight. the probable presence of benresponding fractions, the very While this work was begun as a matter of scientific z e n e and toluene in these small amounts of these made interest, it has resulted in the development of the nitrofractions. From the identisatisfactory purification diffibenzene critical solution temperature method of deterfication of benzene, toluene, cult. It was also observed mining aromatic hydrocarbons in gasoline, which it is and m- and p-xylene in small t h a t t h e solubility of the believed has possibilitiesof application in the petroleum amounts in Ohio and Cananitroaromatic compounds in industry. dian crude p e t r o l e u m b y the gasoline layer was very Mabery,3 and of benzene and appreciable and this caused toluene in Pennsylvania petroleum by Young,4 and consider- considerable loss. Thole8 calls- attention to this mutual ing the close relationship between natural gas and petroleum, solubility as a factor which cannot be entirely neglected in one should expect to find traces of aromatic hydrocarbons in the usual nitration method for determining aromatics and, the gasoline from Pennsylvania natural gas. of course, it is the basis of the nitrobenzene critical solution It seemed worth while to investigate this matter in some temperature method of analysis for aromatics. This direct detail, and the work described in this paper was carried out nitration method was therefore given up as impracticable with the object of getting qualitative proof of the presence for the purpose in view. An entirely satisfactory method proved to be one in which of the aromatic hydrocarbons in this type of gasoline and also an accurate quantitative determination of the small amount the aromatic hydrocarbons were extracted from the crude fractions by liquid sulfur dioxide. The greater solubility of of each present in a typical sample. aromatic hydrocarbons in this reagent as compared with QualitativeIdentifications nonaromatic has been studied by Rrowery7 and by Egloff .E After evaporation of the liquid sulfur dioxide the extracts Attempts were made to identify the aromatic hydrocarbons containing a high concentration of aromatics were nitrated from the sulfonic acids obtained in the preparation of the and the nitro products purified and identified. This principle aromatic-free fractions which were used in the study of the with a special modification has been used by Tausz and Stunitrobenzene critical solution temperature method of analy- berg in isolating toluene and xylene from petroleum fractions. S ~ S . The ~ method that was tried involved salting out the The sample used for these qualitative tests was a straight sulfonates, conversion to the sulfonyl chlorides, and iden- absorption natural gas gasoline, specific gravity 0.6619 tification as the corresponding amides, but these experiments (15.56”/15.56” C.),10identical in source and composition with that used in the quantitative determinations described later. 1 Received March 24, 1926. Presented before the Division of Petro-
I
leum Chemistry at the 71st Meeting of the American Chemical Society, Tulsa, Okla., April 5 to 9. 1926. 2 THISJOURNAL, 16,263 (1924). a A m . Chem. J . , 18, 43 (1896). 4 J . Chem. Soc., 78, 905 (1898). 6 See page 694, this issue.
J. SOC. Chem. I n d . , 8 8 , 39T (1919). Petroleum Reo.,36, 351, 385, 401 (1917); C. A . , 11, 2540 (1917). 8 Met. Chem. Eng., 18, 396 (1918). 2.angezu. Chem., 32,I, 139 (1919); C. A . , 18, 3310 (1919). 10 The gasoline samples were supplied by the United Natural Gas Co..Oil City, Pa. e
7
IiVD USTRIAL AND ENGINEERING CHEXISTRY
July, 1926
A 2000-gram portion of it was subjected to a double fractionation following the usual systematsic procedure in order to eliminate any possibility of the overlapping of the aromatics in the adjacent fractions. The same modified Hempel fractionating column was used as for the preparation of the fractions in the quantitative experiments. The fractions obtained from the second fractionation had the following specific gravities a t 15.56O/15.56O C. taken with a hydrometer : Fraction 5C-95' C. (760 mm.) 95-124' C. Above 124' C.
Sp. gr. 0.6869 0.7282 0.7739
The extractions were carried out by thoroughly shaking the fractionated gasoline samples with three successive portions of liquid sulfur dioxide in a 500-cc. glass-stoppered Erlenmeyer flask immersed in an ice-sodium chloride-calcium chloride mixture contained in an enameled pail which was surrounded by heavy hairfelt. This simple apparatus gave readily a temperature that remained between - 15' and - 18' C. After thorough shaking, the mixture was transferred to a separatory funnel and the lower sulfur dioxide layer run out rapidly into a small flask. The upper layer was returned to the Erlenmeyer flask for the next extraction. The combined sulfur dioxide layers were then allowed to warm up and the sulfur dioxide was evaporated off through a reflux condenser. From 225 cc. of the 50-95' C. fraction treated successively with 40, 20, and 20 cc. of liquid sulfur dioxide, 1.6 cc. of yellowish hydrocarbon residue was obtained after separation of a small water layer from it. From 200 cc. of the 95-124' C. fraction treated with the same amounts of sulfur dioxide, 6.2 cc. of oil was recovered, and 60 cc. of the fraction above 124' C. treated with 15, 10, and 10 cc. of sulfur dioxide gave 4.6 cc. of oil. Qualitative tests were then made on small portions of these extracts. Tests with a solution of bromine in carbon tetrachloride for bromine addition were negative in all three extracts, showing no unsaturated hydrocarbons present. The extracts from the lower two fractions were completely and that from the highest partially soluble in dimethyl sulfate. All three extracts showed a considerable, but not complete, solubility in fuming sulfuric acid (15 per cent sulfur trioxide). These last two tests indicated that the extracts were composed very largely of aromatic hydrocarbons.11 Small portions (1 to 5 cc.) of the extracted hydrocarbons were nitrated following the usual identification conditions.12 After five crystallizations using hot 50 per cent alcohol in the case of the lower two extracts and boiling 95 per cent alcohol for the third, the melting points of the nitro compounds were found to be 89.5-90.0" (cor.), 69.7-70.7' (cor.), and 181.0182.0" C. (cor.), respectively, as the average in each case of two closely agreeing results. The best literature values are as follows: m-dinitrobenzene, 90.00°; 2,4-dinitrotoluene, 70.1 O ; and 2,4,6-trinitro-m-xylene,182' C. Pure 2,4-dinitrobenzoic acid with a melting point of 178.5-180.5° C. (cor.) was also isolated as a residue insoluble in hot 50 per cent alcohol from the first crystallization of the dinitrotoluene. These results prove conclusively the presence of benzene, toluene, and m-xylene in the corresponding gasoline fractions. Quantitative Determinations
The data upon which the quantitative determination of the individual aromatic hydrocarbons was based were obtained in the course of the experiments on the study of the nitrobenKamm, "Qualitative Organic Analysis," 1928, pp. 3 3 and 133. John Wiley & Sons, Inc. l 2 Mulliken, "Identification of Pure Organic Compounds," 1905, Vol. I. 1st ed., pp. 200 and 202. John Wiley & Sons, Inc. 11
723
zene critical solution temperature method of analysis with Sample B.5 The fractionation of this into the three fractions, 50-95', 95-124' C., and residue above 124' C., with the apparatus previously described was assumed to give a sufficiently complete separation of the benzene, toluene, and xylene, considering the small amounts present. The sulfonations which were made for the purpose of getting aromatic-free fractions for the synthetic experiments made possible at the same time a direct measurement of the rise in critical solution temperature due to the removal of each of these aromatics from the crude fractions. Sealed tubes containing equal weights of the crude fraction and pure nitrobenzene, melting point 5" C. (Eastman), were made up in duplicate with the usual precautions for each of the three crude fractions both before and after sulfonation. The critical solution temperatures were determined by the method and apparatus previously described. The rise in critical solution temperature multiplied by the proper proportionality factor determined in the synthetic experiments then gave the aromatic content of each fraction. The data and results obtained are given in the accompanying table. Quantitative Determinations of Aromatics
Fraction
' C.
50-95 95-124
CRITICAL SOLUTIOX Factor % TEMPERATURE aromat- AFomatCrude Aromatic-free ics per ics in fraction fraction s i s e degree fraction Av. C. Av. ' C. C. rise % ' Wt. 1.93 16.91 2.28 0 . 8 4 5 14.63
8.59
13.54
Above124 9 . 7 9 20.17 (olefin-free) a
4.35a 0.890 (cor.) 9 86b 0 . 9 3 8 (cor.)
Correction factor, - 0 . 6 0 degrees.
3.87 9.25
Ratio crude Aromatic fraction in original to crude total gasoline crude 7'0 Wt. 0.299 0.58 benzene 0.148 0.57 toluene 0 . 1 2 5 1.16 xylene Total
2.31
b Correction factor, - 0 . 5 2 degrees.
Because of the effect of unsaturated hydrocarbons in lowering the critical solution temperature in nitrobenzene, it was important to determine whether the crude fractions contained any of these hydrocarbons and, if so, to remove them in such a way as to be able to get the critical solution temperature rise due to aromatics only. Careful qualitative tests with bromine solution in carbon tetrachloride and with alkaline potassium permanganate" showed that unsaturated hydrocarbons were not present in appreciable amounts in the lower two fractions but the amount in the residue above 124' C., which appeared to be about 1per cent, could not be neglected. This fraction was therefore refluxed before the sulfonation step with aqueous mercuric acetate and alcohol mixture following the method described by Danaila, Andrei, and Melinescu.'3 The gasoline was then steam-distilled from the mixture, washed successively with potassium hydroxide, sodium bisulfite, and distilled water until neutral, and dried by calcium chloride. The critical solution temperature of this olefin-free fraction was found to be 0.44 degree higher than that of the crude fraction. The rise due to the removal of xylene was then taken as the difference between the critical solution temperatures of the olefin-free fraction and the product from the subsequent sulfonation. Correction factors as determined by the blank tests in the previous synthetic work6 were applied to the observed rise in the upper two fractions for the effect of the 98 per cent sulfuric acid on the nonaromatic hydrocarbons. 18 Bul. chim. $urd aplicala, SOC. Romdnd Sliintc, 26, Nos. 4-6, 3-49 (1923); C. A . , 18, 3710 (1924).
The Department of Agriculture is planning the construction at the Arlington Experiment Station of a number of concrete slabs to study the effect of various methods of curing. About 40 slabs, containing both admixtures and treated with surfacecuring agents, are to be used.
