January, 1931
IiL'DUSTRIAL A S D ElVGI-VEERING CHEMISTRY
are susceptible to the influence of many factors in the previous history of the sample. Thus, freshly mined lignites with the original moisture content will have an index in the vicinity of 90" C. and a C. 0. T. of 220-230" C. Upon standing in air the lignite loses moisture, adsorbs oxygen, and changes in structure which results in a decrease in both the index and C. 0. T. These phenomena are coincident with a greater susceptibility to spontaneous ignition. Ordinarily lignites are assumed to be more liable to spontaneous combustion than higher rank fuels. Except in the case of anthracite coal neither the index nor the C. 0. T. can be used as a criterion, however, when comparing coals of different ranks. The problem of spontaneous combustion is exceedingly complicated, many factors, such as the heat of wetting, the heat of adsorption, the presence of readily oxidizable organic compounds, etc., being involved. The method seemed suitable for running comparisons in processed and unprocessed coals and was consequently used a t Minnesota to determine the effect of processing by the Fleissner method of drying in saturated steam (6). The results of these tests are given in Table X. It is evident that both the index and C. 0. T. are lowered by processing with the Fleissner process, the average lowering being 20" C. The average lowering for a similar decrease in moisture content upon humidity drying is found from the results of Mr. Brady to be, in the case of the index, about 8" C. and in the case of the C. 0. T. about 13" C. On the other hand, if the lignite is aged by air-drying the corresponding decreases are about 19" and 23" C. if one averages the results of both
INDEX
93
C. 0. T.
I-
I
I
Velva 10 11 13 14 15 17 18 19 Lehigh 16 20
H?O
% 82 84 84 78 78 88 88 88
io
68 55 51 63
io
63 63
85 87
67 70
89
63 66
I
I
210 214 214 214 214 228 228 228
203 206 204 208 204 193 206 211
34.6 32.1 33.5 33.5 34.1 34.9 35.3 36.7
21.3 22.0 23.4 23.4 19.2 18.2 22.7
235 230
210 195
41.1 42.8
30.3 19.2
234 234
196 206
37.0 36.4
19.5 15.8
91.5
Literature Cited Arms, University of Illinois Eng. Expt. Sta , Bull. 128 (April 10, 1922). Davis and Byme, IND. ENG.CHEM.,18, 233 (1926). Holfings and Cobb, J . Gas Lighting, 128, 97 (1914). International Critical Tables, Vo!. I , p. 67, McGraw-Hill, 1926. Lavine and Gauger, IND. ENG.CHEM.,22, 1226 (1930). Lavine, Gauger, and Mann, Zbid., 22, 1347 (1930). Parr and Coons, I b i d . , 17, 118 (1925). Rosin, Fuel S c i e n c e P r a c t i c e , 8, 66 (1929); see also Braunkokle, 27, 241, 282 (1928). (9) Wheeler, J . Chem Soc., 113, 945 (1918)
(1) (2) (3) (4) (5) (6) (7) (8)
Behavior of Certain Thiophanes in Heptane and Naphtha Solutions* R. W. Bost2 and M. W. Conn3 USIVERSITY o r SORTPI CAROLINA, CHAPEL HILL,N C
Tetramethylene and pentamethylene sulfides have Owing to a lack of knowlbeen studied along with ethyl sulfide and thiophene edge of the behavior of the lished an account of the with various reagents in pure n-heptane and three naphthiophanes in hydrocarbon isolation of some alkyl tha solutions. Mercuric chloride, permanganate, hysolution, it seemed desirable sulfides from Ohio petroleum. drogen peroxide, and methyl iodide react with the thioto investigate them f i s t in He also reported some adphanes to form definite products which are easily purisome pure hydrocarbon and ditional sulfur oils obtained fied and identified. Bromine and mercuric iodide finally extend the work to therefrom, which a t that time form unstable products. Nitric acid gives the sulfone more complex s o l v e n t s . had not hitherto been dewhen n-heptane solutions of the sulfides are used, This paper presents a study scribed. In 1906 Mabery and but no definite product is obtained with nitric acid of tetramethylene and pentaQuayle (9) announced the when the naphthas are used as solvents. In general, m e t h y l e n e sulfides w i t h isolation of a new series of the thiophanes resemble the alkyl sulfides more than various reagents in pure nsulfur compounds from Canathiophene. heptane and in three different dian petroleum. Analyses naphtha solutions. showed these compounds to have the general formula C,H&. The name "thiophanes" Materials Used was suggested by these investigators for this new series. More recently Thierry ( I S ) isolated tetramethylene and The 11-heptane used in this work was purchased from the pentamethylene sulfides from Persian petroleum. Eastman Kodak Company and boiled a t 98-98.5" C. A Braun and Trumpler (4) prepared tetrahydrothiophene and detailed method of preparation of the thiophanes used in pentamethylene sulfide. Later Grishkevich-Trokhimovskii this work will appear in another paper. (7') prepared other members of the thiophane series and cerIn order to obtain an accurate knowledge of the chemical tain derivatives of these. behavior of the thiophanes as compared with other classes 1 Received September 27, 1930. This paper contains results obtained of sulfides, a member of the alkyl sulfides and one of the thioin an investigation on "The Preparation and Properties of Thiophanes" phenes were studied along with the thiophanes and under the listed as Project No. 41 of American Petroleum Institute Research. Finansame conditions. Ethyl sulfide and thiophene were the sulfur cial assistance in this work has been received from a research fund of the American Petroleum Institute donated by John D . Rockefeller. This fund compounds used for this comparison. Whether the reactions is being administered by the institute with the cooperation of the Central of ethyl sulfide are typical of all the alkyl sulfides can be Petroleum Committee of the National Research Council. told only by further work. 2 Director of Project KO. 41. The concentration of sulfur used in this work was 1.8 8 American Petroleum Institute Research Assistant.
I
S 1891 Mabery ( 8 ) pub-
INDUSTRIAL A N D ENGINEERING CHEMISTRY
94
per cent. Better results were obtained in the oxidation of ethyl sulfide with hydrogen peroxide when a 3.3 per cent solution of sulfide sulfur was used. A similar concentration of ethyl sulfide waR used in the treatment with methyl iodide. The sulfides were studied with the following reagents: mercuric chloride, mercuric iodide, 30 per cent hydrogen peroxide in glacial acetic acid, nitric acid (sp. gr. 1.42), potassium permanganate, bromine, and methyl iodide. Table I gires the constants for the naphthas studied. The solvents were obtained from commercial laboratories. The source of naphtha 1 was natural gas. It was purified by an oil scrubber, then with sulfuric acid, water, and sodium carbonate solution, and finally allowed to stand over solid potassium carbonate. It was then fractionated an3 the fraction known as naphtha 1 used for this work. Naphthas 3 and 7 were obtained from oil companies and used in the state in which they were supplied. Characteristics of N a p h t h a s NAPHTHA 1 NAPHTHA 3 NAPHTHA 7 Gravity, ' A. P. I. at 60' F. 78.3 54.8 49.3 Color, Saybolt 25 Sulfur, yo 0.005 "$26 0.036 ASSAY DISTILLATION Over, O F. 130 202 293 Dry, F. 216 390 404 OC. % OC. % OC. % 60 5 120 14 3 150 130 31 28 65 160 34 140 57 67 70 170 65 150 66 83 75 180 86 89 80 160 79 190 93.5 .. 200 96.7 170 88 .. .. 180 94 . .. 190 96 . .. .. 200 98 ... Total 96 98: 0 Residue 1.4 1 1.6 Loss 2.6 1 0.4 Doctor test Negative Negative Negative Bromine number 0.05 2.5 2.2 Molecular weight 84 128 141 Unsaturates, % Trace 2.0 1.9 Table I-Physical
+
....
..
...
...
....
Experimental MERCURIC CHLORIDE-TOa solution of the sulfide in 5 cc. of heptane was added an equivalent amount of mercuric chloride in alcoholic solution. The precipitate was filtered and dried in a vacuum desiccator overnight. In most cases the melting point was not altered by recrystallization from absolute alcohol. By using a 0.237-molar solution of mercuric chloride in alcohol it is possible to detect ethyl sulfide in heptane solution in concentrations of 595 parts per 100,000, tetramethylene sulfide in concentrations of 23 parts per 100,000, and pentamethylene sulfide in concentrations as low as 17 parts per 100,000, Tetramethylene and pentamethylene sulfides form mono-salts with mercuric chloride; ethyl sulfide forms mainly the di-salt, but by exercising extreme care the writers were able to obtain the mono-salt described by Faragher, Morrell, and Comay (6). Thiophene does not react under the same conditions. When the naphthas were used as solvents, immediate precipitates were obtained with the exception of thiophene. The derivatives from naphtha 1 were usually pure after one recrystallization from alcohol, while to purify those from naphthas 3 and 7 several recrystallizations were necessary. MERCURIC IODIDE-A solution of the sulfide in heptane was treated with a saturated alcoholic solution of mercuric iodide. An immediate precipitate was formed with tetramethylene sulfide. The pentamethylene sulfide on standing overnight formed a mass of needles. When the two solutions were cooled to -12" C. a quantity of needles was formed. Ethyl sulfide did not yield a precipitate under the same conditions; however, upon evaporation of the solvent in a vacuum desiccator a yellow product was formed which soon decomposed into red crystals of mercuric iodide and liberated ethyl sulfide.
Vol. 23, No. 1
This compound agreed in properties with that obtained by Smiles ( I @ , who obtained diethyl sulfide-mercuric iodide from acetone solution. Only approximate melting points could be obtained owing to rapid decomposition of the products. Analyses of the products were not possible. When naphthas were used as solvents no precipitate had formed after standing 24 hours, but when the reaction products were placed in a freezing mixture a heavy precipitate was obtained in 31/2 hours with the thiophanes. With ethyl sulfide the product was obtained only upon evaporation of the naphtha-alcohol solution in vacuum. No reaction was obtained with thiophene in any of the solvents under the same conditions. NITRICACID-TO an equivalent amount of the sulfide in 5 cc. of heptane was added dropwise the calculated amount of nitric acid (sp. gr. 1.42) to form the sulfone. Fuming nitric acid gave better results with ethyl sulfide. The apparatus consisted of an &-inch(20-cm.) test tube fitted with a small reflux condenser. The test tube was surrounded by a water bath during the addition of the acid. The reaction mixture was then cautiously warmed on a steam bath a t intervals until the green color of the acid layer had practically disappeared. The product was diluted with 10 cc. of water, neutralized with dilute sodium hydroxide, using phenolphthalein as indicator, the heptane layer removed, and the aqueous layer extracted twice with 5 cc. of ether. The ether extracts were added to the heptane layer and evaporated in a vacuum desiccator. Sulfones were obtained in all cases when n-heptane was used as a solvent with the exception of thiophene. Briihl (5) has shown that thiophene vapors when passed over nitric acid yield a nitro derivative. Under the conditions of this reaction neither oxidation nor nitro products could be isolated. No definite products could be isolated when the naphthas were used as solvents. POTASSIUM PERMANGANATE-The method employed in this oxidation was similar to that used by Mabery and Quayle (9) with slight modifications. An equivalent amount of the sulfide in 10 cc. of the solvent was treated with 50 per cent excess of the calculated amount of potassium permanganate in thirty times its weight of water to form the sulfone. The heptane solution of the sulfide was cooled to 0" C. with a freezing mixture and the permanganate added with shaking as fast as it was decolorized. When all the permanganate had been added, the precipitate of manganese dioxide was dissolved by treating with a solution of sulfurous acid a t room temperature. An excess of the reagent was avoided. The resulting solution was evaporated to dryness on a steam bath. The residue was extracted with several portions of ether, the ether extracts boiled with charcoal, filtered, and the ether evaporated. In some cases where heptane was used as a solvent recrystallization was unnecessary. Where the naphthas were used as solvents from two to four recrystallizations were necessary to obtain the pure product. This mas particularly true with naphthas 3 and 7 . HYDROGEN PEROXIDE-An equivalent amount of the sulfide in 10 cc. of the solvent was treated with the calculated amount of 30 per cent hydrogen peroxide dissolved in glacial acetic acid to form the sulfone. A slight rise in temperature was noted after the addition of the acid-peroxide mixture. The reaction mixture was gently heated on a steam bath for 3 hours, then transferred to an evaporating dish and the acidsolvent mixture removed. The residue was taken up in anhydrous ether and the latter removed in a vacuum desiccator. When the naphthas were used as solvents it was necessary to recrystallize the products from two to four times. Thiophene failed to yield a product. METHYL IODIDE-TO an equivalent amount of the sulfide in
INDUSTRIAL AND ENGINEERIA'G CHEJIISTRY
January, 1931
5 cc. of the solvent was added the calculated amount of methyl iodide to form the iodomethylate. There was no immediate precipitate. After 24 hours crystals began to appear in the case of tetramethylene and pentamethylene sulfides. After several days a mass of yellow crystals was formed with these sulfides. Ethyl sulfide yielded a reddish oil, which did not solidify when cooled to -15' C. The precipitates were filtered by suction, dried in a vacuum desiccator, and the melting points determined. Recrystallization from absolute alcohol did not alter the melting point when heptane was used as a solvent. When the naphthas were used as solvents, the impurities increased in the order in which the naphthas are given. Repeated recrystallizations were necessary in case of naphtha 7. Thiophene failed to yield a precipitate a t the end of 3 weelis. of E t h y l Sulfide i n H e p t a n e a n d N a p h t h a Solutions COMPOCND CRYSTALLINE CRYSTAL MELTING SOLVENT POINT REAGENT FORMED FORM T a b l e 11-Derivatives
c.
HgCln HgIz
(CzHJzS.2HgCIz Colorless needles (CzH.)zS.HgIz Lemon-yellow needles, decompose on standing
