JANUARY, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
‘original slag’ gave a different type of diffraction pattern. Copper K radiation was used in both examinations.” This further indicates the undesirability of aging a premixture of triple superphosphate with a wetted slag of high fluorine content. Plant culture studies are planned to determine whether the fluorine content of such mixtures exerts any influence upon assimilation of the P206content of the mixtures, identical mixtures of fluorine-free slags being used as controls. The authors believe it desirable to restrict the slag additions to the latter type until conclusive plant response evidence is obtained relative to the use of the slags of high fluorine content.
Literature Cited (1) Ames, J. W., Ohio Agr. Expt. Sta., Monthly Bull. 1, 359-62
(1916). Barnette, R. M., Soil Sci., 18, 479 (1924). Ibid., 21, 463 (1926). Ibid., 22, 459 (1926). Beeson, K. C., and Ross, W. H . , IND.ENG. CHEW, 26, 992 (1934). (6) Cowles, A. H., M e t . & Chem. Eng., 17,,664-5 (1917). (7) Cowles, A. H., and Scheidt, A. W., paper pub. by Electrical Smelting and Alum. Co., Sewaren, N. J.. 1917.
(2) (3) (4) (5)
57
(8) Hartwell, B. L., and Pember, F. R., Soil Sci., 10, 57-60 (1920).
(9) MaoIntire, W. H . , Univ. Tenn. Agr. Expt. Sta., Bull. 115, 19 (1916). (10) MacIntire, W. H., Ellett, W. B., Shaw, W. M., and Hill, H. H., Ibid., 152 (1934); Va. Agr. Expt. Sta., Tech. Bull. 54 (1934). (11) MacIntire, W. H., and Sanders, K. B., J. Am. Soc. Agron.. 20, 764-70 (1925). (12) MacIntire, W. H., and Shaw, W. M., Ibid., 26, 656-61 (1934). (13) MacIntire, W. H., Shaw, W. M., and Robinson, B., Univ. Tenn. Agr. Expt. Sta., Bull. 155 (1935). (14) MacIntire, W. H., and Shuey, G. A., IND. ENQ.CHEM.,24, 93341 (1932). (15) MaoIntire, W. H., and Willis, L. G . ,Ibid., 6, 1005-8 (1914). (18) Midgley, A. R., J. Am. SOC. Agron., 24, 822-35 (1932). (17) Morse, H. H.. Soil Sci., 39, 177-97 (1935). (18) Sohollenberger, C. J., Ibid., 14, 347-62 (1922). (19) Shaw, W. M., and MacIntire, W. H., Ibid., 39, 369-75 (1935)., (20) Shedd, 0. M., Ibid., 14, 233-46 (1922). (21) Thomas, W., Science, 71, 422-3 (1930). (22) Weiser, V. L., Univ. Vt. Agr. Expt. Sta., Bull. 356 (1933) (23) White, J. W., Pa. Agr. Expt. Sta., Bull. 220 (1928). (24) Wianoko, A. T., Walker, G . P., and Conner, S. D., Ind. (Purdue) Agr. Expt. Sta., Bull. 329 (1929).
RECEIVED June 1, 1935. This paper is a contribution of The University of Tennessee Agricultural Experiment Station in collaboration with the Chemical Engineering Division of T. V. -4.
CHEMISTRY ’ofthe ACETYLENES 111. Cracked Gasoline as Source of Alpha-
Olefins for Preparation of Acetylenes’ HOMER J. HALL* AND G. BRYANT BACHMAN The Ohio State University, Columbus, Ohio
T
HE development of the chemistry of the higher acetylenes has long awaited a cheap source of these highly reactive hydrocarbons. The so-called alpha-acetylenes in which the triple bond is located a t the end of the carbon chain are especially interesting because of the labile hydrogen atoms they contain. By substitution or addition reactions it is possible to proceed from alpha-acetylenes to aldehydes, ketones, acids, olefins, hydrocarbons, and a great variety of other derivatives. A number of methods of synthesizing the higher acetylenes have been developed, and a few of them start withthe relatively cheap acetylene (C2Hz)itself; but for the most part dehalogenation of suitable chlorinated or brominated hydrocarbons is utilized. All of these methods have failed, however, to make commercially available a t a low price any one of the alpha-acetylenes, usually because of the high cost of the starting materials. In attempting to find a cheap source for some one higher acetylene for purposes of research, the possibility was considered that cracked gasoline might be fractionated to yield For the first two articles in this series see J . Am. Chem. Soc., 56, 2730 (1934); 57, 2167 (1935). Present address, Standard Oil Development Company, Elizabeth, N. J.
’
olefins of the type RCH=CH2 which on treatment with halogens and then with alkalies would give the corresponding acetylenes, RC=CH. A few instances of the fractionation of cracked gasoline have already been summarized in the literature ( 5 ) . These reports, however, point uniformly to the absence of alpha-olefins of the desired type in any considerable quanti&, and indeed theoretical reasons have 1 - P e n t y n e and been advanced to explain the 1 - h e x y n e are predominant formation of conveniently obdisubstituted and branchedchain olefins in the cracktained in a pure ing units. However, certain form from the preliminary i n f o r m a t i o n c orresponding which we obtained indicated olefins distilled that gasoline from the Gyro from Gyro procprocess probably contained considerable amounts of 1ess gasoline. p e n t e n e a n d 1-hexene. The olefins, 1Wagner (1%) h a s a l r e a d y pentene, and 1pointed out that the Gyro hexene are presprocess produces a different type of gasoline from that ent to the extent obtained in most other crackof about 5 and 4 ing processes. per cent, respecA t a b l e was first contively, in t h e structed showing (a)the boilo r i g i n a l mateing points of all known hydrorial. carbons boiling below 80’ C.,
58
INDUSTRIAL AND ENGINEERING CHEMISTRY
(b) the boiling points of the dibromides of all olefinic hydrocarbons listed in (a), and ( c ) the boiling points of all acetylenic hydrocarbons derivable from the dibromides listed in ( b ) , From this table it was evident that 1-pentene and 1-hexene could probably be obtained in 80 to 90 per cent purity by fractionation alone and that subsequent bromination and refractionation would yield very pure dibromides of the above two olefins. Dehalogenation to the corresponding acetylenes would introduce still further purification. The situation in regard to 1-heptene was not nearly so favorable, and it became obvious that, unless many of the possible isomers were absent, satisfactory separation could not be attained in a reasonably short time. Following this preliminary work a small sample (5 gallons) of Gyro process gasoline was fractionated and found to yield 1-hexene in sufficient purity to enable 1-hexyne to be synthesized from it in high purity. Other substances present were not isolated in this run. In the experimental part which follows, a description of the fractionation of a much larger sample and the conversion of the olefins obtained into acetylenes will be given.
VOL. 28, NO. 1
heating element of No. 22 nichrome wire, and then insulated with ordinary 85 per cent magnesia pipe lagging. The column heads were of the total condensation type with a variable take-off controlled by a 2-mm. stopcock. Temperatures were taken in the vapors at the head of the column using thermometers compared with standards calibrated by the Bureau of Standards. During the final distillations the temperatures were taken in a continuous Cottrell reboiler constructed according t o the specifications of Bruun and Schicktanz (9). Distillations were carried out with a reflux ratio of about 15 to 1.
Fractionation The first fourteen fractions of the charging stock were subjected to batch distillations; that is, each fractio'n was refractionated as a unit by itself. Similar fractions of these distillates were then combined and used as charges in the next refractionation and so on through five complete fractionations for the 1-pentene range and four for the 1-hexene range. The following table indicates the columns used in each of these refractionations : No.
Pentene Range
Hexene Range
1 2
History of Charging Stock
3
The highly cracked distillate used in this work was kindly furnished by the Pure Oil Company. It was obtained from the Gyro process stabilizer bottoms of the Heath Refinery at Newark, Ohio. The preliminary observations indicated a large content of mixed butenes, which are difficult to handle in laboratory fractionating equipment. Hence, the original lot of gasoline was treated with live steam a t the refinery until about one-fourth had evaporated. The 50 gallons remaining had a density of 0.696 a t 20" C. as compared to the original density of 0.683 a t the same temperature. The unsaturation of the sample as determined by sulfuric acid absorption was about 65 per cent. The 50-gallon lot was given two preliminary distillahions from bright metallic copper trimmings to remove corrosive materials and high-boiling residue. The remainder was then charged into a large fourteen-plate bubble-cap copper column and fractionated. Eighteen fractions of convenient size for use in the smaller laboratory columns were taken. Because of the loss of residues and low-boiling materials principally, and occasional leaks and storage losses, the remaining gasoline from the treatment amounted to only 22 gallons. This material constituted the charging stock for the smaller columns.
Design of Laboratory Columns Four different fractionating columns, C, MI, 1M2, and M1M2, were used: Column C (in general, the most satisfactory) was a Carborundum-packed column made of Pyrex glass similar to the one designed by Peters and Baker (IO). Adiabatic conditions were maintained by a dead air space and a heated air jacket surrounding the column. The packed section was 150 cm. high and 3.15 cm. in diameter. This large diameter was necessary in order to handle the volume of liquid to be distilled within a reasonably short time. The packing for the column consisted of ordinary porous Carborundum reduced from larger lumps t o 3-6 mesh with the sharp edge of a hatchet. Columns M I and M 2were identical single copper spiral columns of the Midgley type (9). Each spiral consisted of fifty turns, 7.6 om. in diameter with a 0.96-cm. rise per turn, mounted on a center post 0.22 cm. in diameter. The path followed by the rising vapors was approximately 7.6 meters long, the columns being 48 cm. high. The interiors of the columns were coated with 20- t o 60-mesh Carborundum as suggested by Midgley. Tests indicated that column C was somewhat more efficient than either M I or M2, so the two Midgley columns were opened a t one end, flanges were brazed on them, and they were then bolted together using a cork gasket to prevent leakage. This aolumn was designated as M&f2. Columns M I , Mz, and during use were wrapped with asbestos paper, wound wlth a
FIMZ
4 5
The materials finally isolated possessed the following constants: 1-pentene, boiling point 29.0-30.0" C. (745 mm.), di0 0.6442, n'i 1.3692 [compare Wilkinson's synthetic product ( I S ) ] ; 1-hexene, boiling point 62.5-63.5" C. (745 mm.), d:' 0.6766, n2i 1.3872 [compare Wilkinson ( I S ) and Boord ( d ) ] . Although no effort was made to obtain a complete analysis of the gasoline, certain other substances were found to be present. These included 1-butene, 2-butene, butadiene, isoprene, n-pentane, and n-hexane. All of these except the last two were confirmed by converting them into their dibromides which possessed the properties recorded for them in the literature. Although special attention was paid to the material boiling in the range between the butenes and isopentane, 3-methyl-1-butene was found with certainty not to be present in more than traces. Likewise, in the heptene range no plateau was found which was large enough to in&cate the presence of an appreciable amount of any one hydrocarbon. By taking into consideration the percentage recovery of the fractions on each distillation and the analysis as shown in the subsequent bromination, it is possible to give a rough estimate of the amount of each of the principal products which was present in the charging stock and in the original material: Hydrooarbon 1-Pentene 2-Pentene n-Pentane 1-Hexene
Per Cent in Stock
Per Cent in Original
11.1
4.9 0.9 2.0 4.0
2.0
4.5 9.1
The figures given for the analysis are a conservative estimate, since they represent the amount of purified dibromide (or hydrocarbon) obtained after bromination. The small amount of 2-pentene and the absence of any noticeable amount of 3-methyl-1-butene are interesting. Hurd (7) states that the pyrolysis of 1-pentene gives rise to some 2-pentene but that more 3-methyl-1-butene is formed than any other pentene. It appears then that for some reason the expected thermal isomerization of the alpha-olefins does not occur in the Gyro process to any appreciable extent, and that the principal olefins present in the pentene and hexene ranges are the straight-chain alpha-olefins.
Bromination Brominations were carried out below -20' C. in a solid carbon dioxide-chloroform cooling bath in order to minimize
JANUARY, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
substitution. The reaction was vigorous a t this temperature and seemed to be even more so than a t 0" C. or a t room temperature. The hydrocarbon was diluted with an equal volume of chloroform, and the mixture was vigorously stirred, particularly as the end point (slight permanent orange color) was approached. The bromination of 500 grams of hydrocarbon required from 4 to 6 hours. The products were fractionated under reduced pressure after distilling off the unchanged hydrocarbon and the solvent. From 70 to 75 per cent of the theoretical amounts of lJ2-dibromopentane [boiling point 79.0-80.0" C. (24 mm.), d;O 1.6692, n2z 1.5096 (4, I S ) ] and 1,2-clibromohexane [boiling point 80.0-81.7" C. (10 mm.), dgO1.5784, nzz 1.5034 (4, IS)] was obtained, calculated on the basis of the olefin used. From 80 to 89 per cent of the theoretical amount of bromine was required. The brominations indicated that the olefins which had been isolated were apparently not entirely pure even after four or five refractionations, but were nevertheless quite satisfactory as a soume of the 1,2-dibromides. In order to determine whether so many distillations were desirable from a practical standpoint, a fresh sample of the original vaporphase-cracked distillate was run through the large copper bubble-plate column and the pentene and hexene fractions (boiling points 25-35" and 60-66" C.) were each refractionated once in column C, using a reflux ratio of roughly 20 to 1. The pentene and hexene cuts (boiling points 28-32' and 6264' C.) from this refractionation were brominated. The dibromides after a single distillation through column C were pure and gave nearly as good yields of the acetylenes as those obtained from the more highly fractionated olefins.
Dehalogenation The purified dibromides were dehalogenated with' a suspension of 10 moles of potassium hydroxide in 5 volumes of mineral oil ( 1 ) . Because of the low boiling points of the bromoolefins the dehalogenations were not as complete as was obtained previously by one of the authors with the corresponding heptene dibromide (1). From the dibromopentane 33 per cent of the theoretical amount of 1-pentyne and 42 per cent of the theoretical amount of bromopentene were obtained. The b~~ornopentenewas subsequently converted into 1-pentyne by refluxing for 5 hours with 3 moles of 25 per cent alcoholic potassium hydroxide. The total yield of 1-pentyne was 55 per cent. The product possessed the following physical constants: boiling point 39.5-41.0" C. (747 mm.), d:' 0.6945, n2z 1.3847 (B). Its mercury derivative (8, 11) melted a t 117.9-118.3' C. From the dibromohexane 57 per cent of the theoretical amount of 1-hexyne and 30 per cent of bromohexene were obtained. Further dehalogenation of the brorriohexene with alcoholic potassium hydroxide brought the fins1 yield of 1-hexyne to 76 per cent. The physical constants were: boiling point 71-72" C. (749 mm.),
DIORAMA OF
THE
d;' 0.7170, nzz 1.3988 (6). 11) melted at 96.0-96.4' C.
59
The mercury derivative ( 8 ,
Summary Exhaustive fractionation of a vapor-phase-cracked gasoline produced by the Gyro process showed that there was approximately 5 per cent of 1-pentene and 4 per cent of 1hexene in the original material. These results stand in direct contradiction to statements in the chemical literature that alpha-olefins will not be found in appreciable quantities in cracked distillates. Of the two compounds known to result from the thermal isomerization of 1-pentene, only a small amount of 2-pentene was found and 3-methyl-1-butene was not indicated. Other substances found to be present but not determined quantitatively were 1-butene, 2-butene, butadiene, isoprene, n-pentane, and n-hexane. No indications of the presence of naphthenic hydrocarbons were found. The 1-pentene and 1-hexene isolated were shown to be satisfactory raw materials for the synthesis of 1-pentyne and 1-hexyne. This was accomplished by bromination, fractionation of the dibromides, and dehalogenation of the purified dibromides.
Acknowledgments The authors are indebted to the Pure Oil Company for the gasoline and to Thomas Midgley for the Midgley columns used in this work. It is a pleasure also to acknowledge the use of the fractionating equipment of the Department of Chemical Engineering, The Ohio State Cniversity, which was put a t the writers' disposal by James R. Withrow, and the kind personal assistance of Joseph H. Koffolt of the same department.
Literature Cited (1) Bachman, G . B., and Hill, A. J., J . Am. Chem. SOC.,56, 2730 (1934). (2) Bouis, M., Ann. chim., 9, 461 (1928). (3) Bruun and Schicktanz, Bur. Standards J . Research, 7, 865 (1931). (4) Dykstra, Lewis, and Boord, J . Am. Chem. SOC.,52, 3402 (1930); Schinitt and Boord, Ibid., 54, 760 (1932). (5) Ellis, C., "Chemistry of Petroleum," pp. 116-19, New York! Chemical Catalog Co., 1934. (6) Grignard, Lapayre, and Tcheoufaki, Compt. rend., 187, 517 (1928). IND.ENG.CHEM.,26, 51 (1934). (7) Hurd, C.D., (8) Johnson and McEwen, J . Am. Chem. SOC.,48,469 (1926). (9) Midgley, T., IND.ENG.CHEM.,Anal. Ed., 1, 86 (1929). (10) Peters, W. A., Jr., and Baker, T., IND.ENG. CHEM., 18, 69 (1926). (11) Vaugh, T.H., J . Am. Chem. SOC.,55, 3454 (1933). (12) Wagner, Refiner Natural Gasoline Mfr., 10, 70 (1930). (13) Wilkinson, R.,J . Chem. SOC.,1931, 3057. RECEIVED September 30,1935.
MOXSANTO CHEMICAL COMPANY'S WORKS,MONSANTO, ILL.
.
