INDUSTRIAL AND ENGINEERING CHEMISTRY
2318
The source of the surprisingly large quantity of chrysene will be discussed in the following paper (48). ACKKOWLEDGMMENT
The authors wish to express their gratitude to H. E. Charlton, Chief Engineer of Petrocarbon Ltd., who collaborated in all questions of engineering and who was responsible for the design and construction of the pilot plant on which many of the results recorded in this and the following papers were obtained. LITERATURE CITED
Beilstein, “Handbuch der organischen Chemie,” Val. V, p. 483, Berlin, J. Springer, 1922; Suppl. Val. V, p. 233 (1930). Ibid., Suppl. Vol. V, p. 63 (1930). Blanksma, J. J., Rec. trav. chim.,21,327 (1902). Charlton, H. S., Manchester Association of Engineers,-1950. Diels. 0.. and coworkers. Ann.., 460. 98. (1928). ~ , Fittig, R:,Ibid.,141, 134 (1867). Geniesse, J. C . , and Reuter, R., ISD. ENG.CHEM.,22, 1274 (1930); 24, 219 (1932). Gooderham, W. J., J . SOC.Chem. Ind.. 5 4 , 2 9 7 T (1935). Groll, H. P. A., IND.ENG.CHEM.,25,784 (1933). Grosse, A. V.,U. S. P a t e n t s 2,124,566, 2,124,567 (July 26, 1938). Guttman, I,., Westrum, E. F., and Pitser, K. S., J . Am. Chem SOC.,65, 1247 (1943). Hague, E. S . ,and Wheeler, R. V., J . Chem. SOC.,1929,378. Harries, C., and T a n k , L., Ber. deut. chem. Ges., 41, 1701 (1908). ESG.CHEM.,39, 1564 (1947). Henriques, H . J., IND. Herington, E. F. G., and Rideal, E. K . , Proc. Roy. SOC.(London) 184A, 447 (1945). Hooa, H . , Verheus, J., and Zuiderweg, F. J., Trans. Faraday Soi.,,35, 993 (1939). Ipatieff, V. N., and Schmerling, L., J . Am. Chem. Soc., 59, 1056 (1937 1. ,Jacobsen, O., Rm.deut. chem. Ges., 19, 1218 (1886). Joshel. L. AI.. and Butz, L. M., J . Am. Chem. Soc., 63, 3350 (1941). Klages, A . , and Keil, R., Ber. deut chem. Ges., 36, 1632 (1903). Koch, H . , Brennsfof-Chem., 20, 1 (1939). Kraemer, G., and Spilker, A,, Ber. deut. chem. Ges., 23, 3276 (1890).
Vol. 43, No. 10
(23) Lummus Co., Brit. P a t e n t 590,590 (July 23, 1947). (24) MoldavskI, B. L., and Kamusher, H . , Compt. rend. acad., sci. U.R.S.S., I , 355 (1936); Chem. Zentr., 1 9 3 6 , I I , 2339. (25) Moldavskl, B. L., etal., J . Gen. Chem. (U.S.S.R.), 7, 169, 1835, 1840 (1937); Chem. Zentr., 1 9 3 7 , I I , 1546; 1 9 3 8 , I I , 1023. (26) Morrell, J. C. (to Universal Oil Products Co.), U. S. P a t e n t s 2,124,583,2,124,585 (July 26, 1938). (27) Morrell, J. C., and Grosse, A. V., Ibid., 2,124,584, 2,124,586 (July 26, 1938). (28) Pitkethly, R. C., and Steiner, H., Trans. Faraday Soc., 35, 979 (1939). (29) Pitser, K. S., J . Chem. Phys., 5 , 469, 473 (1937). (30) Schneider, V., and Frolich, P. K., IND. ENG.CHEM.,23, 1405 (1931) (31) Shuikin, N. J., Uspekhi K h i m . , 15, 343 (1946). (32) Steiner, H., J. Am. Chem. SOC.,67,2052 (1945). (33) Steiner, H., J. I n s t . Petroleum, 33, 410 (1947). in press. (34) Steiner, H., and Rowley, D., Trans. Faraday SOC., (35) Taylor, H. S., and Turkevich, J., Ibid., 35, 921 (1939). (36) Tiffeneau, M.,Compt. rend.. 134, 846 (1902); Ann. chini., [8I 10,166 (1907). (37) Tilicheev, M. D., and coworkers, Ber. deut. chem. Ges., 62, 658 (1929); Khim. Tverdogo Toplica, 8 , 548, 617, 876 (1937); reviewed in Oil Gas J . , 39, No. 40, 41. 45, 46 (1941). (38) Tropsch, H., and Mattox, W.J., IND.ENG.CHBM.,AN.IL. ED., 6, 104 (1934). (39) Turkovich, J., Fehrer, H., and Taylor, H. S., J . Am. Chern. Soc., 63,1129 (1941). (40) Voswinkel, A,, Ber. deut. chem. Ges., 22, 315 (1889). (41) Weger, M., and Billmann, A , , Ibid.,36, 640 (1903). (42) Weizmann, C., et al., Brit. P a t e n t 552,216 (March 29, 1943): Ibid., 574,963, 574,973 (Jan. 29, 1946); Ibid., 575,383 (Feb. 15, 1946); Ibid., 575,766, 575,768, 575,771 (March 5, 1946). (43) Weismann, C., et al., ISD.ENG.CHEM.,43,2318 (1951). (44) Ibid., p. 2322. (45) Weismann, C . , et al.,J . SOC.Chem. Ind., 67, 114 (1948). (46) Weismann, C., et aZ., U. S.P a t e n t 2,349,781 (May 23, 1944); Ibid., 2,397,715 (April 2, 1946). (47) Wheeler, R . V., and Wood, W. L . , J . Chem. SOC.,1930, 1819.
.
RECEIVED December.18, 1947. Contribution from the laboratories of The Weizmann Institute of Science, Rehovoth, Israel: Petrocarbon Ltd., London Bridge, London E.C. 4, England; and the Grosvenor Laboratory, 25 Grosvenor Crescent Mews, London S.W. 1, England.
( A romatizing Cracking of Hydrocarbon Oils)
POLYCYCLIC FRACTIONS WITH
CHAIM WEIZMANN, ERNST BERGMe4NN, H. S. BOYD-BARRETT, HERBERT STEINER, AND MAX SULZBACHER, J. R. HOLKER, ERNA MANDEL, JOHN PORGES, AND DERRICK ROWLEY The Weiamann Institute of Science, Rehowoth, Israel
T
HIS paper deals with those constituents of the aromatization
product of a naphthenic naphtha described in the preceding paper, which boil above approximately 200’ C. [see Table I in (64)],with their nature, their identification-as far as it has been achieved-and the presumable mechanism of their formation. NAPHTHALENE AND ALKYLNAPHTHALENE FRACTIONS
Table I lists the constituents of these fractions. The tetrahydronaphthalene contained in this fraction was accompanied by other hydrocarbons, some of them saturated, some unsaturated and polymerieahle t o a viscous oil, possibly 1,2-dihydronnphthalene (22, 60). The naphthalene itself had a high degree of purity; when washed free from adherent oil with isopropyl alcohol, treated with a small amount of aluminum chloride (0.1 to 0.2% by weight) a t 200 C., washed with sodium hydroxide solution, and redistilled, it met the strictest specifications.
For the isolation of the alkylnaphthalenes, use was made of the picrates. Hoxever, it has to be borne in mind that, more frequently than generally known, picrates of similar hydrocarbons tend to form mixed crystals. This has been observed for the following pairs: Naphthalene and 1-methylnaphthalene 1-Methylnaphthalene and 2-methylnaphthalene 2-Methylnaphthalene and 1,2-dimethylnaphthalene 1,2-Dimethylnaphthalene and 1,2,3-trimethylnaphthalene 1,2,5-Trimethylnaphthalene and 1,2,5,&tetramethylnaphthalene (60) Phenanthrene and 9-methylphenanthrene (9, SI, 61) Regarding the di- and trimethylnaphthalenes, experience has shown that the 2,6-compound, a mixture of the 1,6- and 1,T-compound, and the 1,2-compound can be separated from each other to a considerable extent by fractional distillation, the 1,2-compound-like o-xylene-showing the highest boiling point.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
October 1951
1,7-Dimethylnaphthalene,
177-187~
B.p., 136-137O/14 mm.
naphthoquinone: m p 93-94'' (6s) Picrate: m.p., 123'; 1,'7:himethyl-5,& naphthoquinone: m.p., 135-136O
2319
.........
(40)
-
Equally, in the series of trimethylnaphthalene, the 1,2,6-compound concentrates in the last parts of the appropriate fraction. It is interesting to compare these results with a list of the diand trimethylnaphthalenes observed in coal tar (Table 11) (58, 39,62).
TABLE 11. DI-
AND
TRIMETHYLNAPHTHALENES IN COALTAR
Dimethylnaphthalenes 122,31:62,61,72,7-
Trimethylnaphthalenes 2,3,61,3,7-
1,8-
In Rumanian gas oil, Gavat and Irimescu ( $ 7 ) have found the following dimethylnaphthalenes: 1,2-; 1,3-; 1,6-; 1,7-; 2,3-; 2,6-; and the following trimethylnaphthalenes: 1,2,5-; 1,2,6-; 1,3,6-; 2,3,6-; in a Russian petroleum, Nametkin et al. (44) found 1,6- and 1,7-di- and 1,2,6-trimethylnaphthalene. ANTHRACENE FRACTION
Table I11 supplies the data on the anthracene fraction. The anthracene-phenanthrene ratio varies with the strictness of the aromatizing conditions, while the sum of the two hydrocarbons is constant; more phenanthrene is formed under more stringent conditions [for analysis see (55,@ ) ] .
tained by distillation in a high vacuum. From it, two substances have been isolated, picene [melting point, 350" C. ( 4 ) ] ,and the golden leaflets of a hydrocarbon, C26H18, which has the same composition and almost the same melting point of 288' C. (from xylene or butyl acetate) as the 2',3'-phenanthra-1,2-anthracene of Cook (16). Cook has compared these two substances and found them to be different (depression of the melting point). The hydrocarbon gives a brown-red diquinone, C26H,,Oa, of melting point 214' C. (from toluene), which shows the same (vio1.et) color reaction with sulfuric acid and the same solubility in aqueous sodium bisulfite solution as chrysoquinone, and was, therefore, 1,2,2',1'-naphtho-7,8likely t o be a dibenzochrysene-via., benzophenanthrene.
THEORETICAL CONSIDERATIONS
In the precrding paper (64)the fact has been commented upon that among the side chains observed in the aromatization product, methyl is the prevalent one and that otherwise the only side chains which are stable are those containing a double bond in conjugation with the aromatic system. The latter fact provides an explanation for the occurrence, in the polycyclic fractions, of acenaphthene which may owe its formation to a cycloisomerization of 1-vinylnaphthalene, a reaction resembling the fluoranthene synthesis discovered by Cook and Lawrence ( 1 8 )
CHRYSENE FRACTION
The data on the chrysene fraction are given in Table IV. PITCH
From the fraction above the chrysene cut, the pitch, a certain amount of a volatile, but highly viscous distillate could be ob-
TABLE 111. ANTHRACENE FRACTION (160-200°/6 mm.; 140-190°/2 mm.) Physical Constants Identification M.P., 215O Mixed m.p. M.P., 202-203" Quinone: m.p., 175O; trinitro; benzene adduct: m.p., 138 2,7-Dimethylanthracene M.p., 237O Mlxed m.p. Phenanthrene From crude anthracene by ex- M.p., 99O Mixed m.p. traction with benzene 1-Methylphenanthrene From mother liquors of recrys- M.p., 123O Mixed m.p. tallization of phenanthrene 3-Methylfluorene From crude phenanthrene by M.P., 84-85' Mixed m.p.; 3-methylfluorefusing with KOH (36, 6 1 ) none: m.p., 68O (63)
Substance Anthracene 2-Methylanthracene
Method of Isolation Cooling a t O o
Remarks
.............
............. Calcd. for CieHid: C, 93.2; H, 6.8. Found: C, 92.9; H, 6.9
............. .............
3-Methylfluorene gives no m.p. depression with the 2-isomer of m.p. 104' (equal parts)
2320
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY TABLEIV.
Substance Chrysene
Method of Isolation Cooling a t O', washing with petroleum ether
1,2-Benzanthracene From petroleum ether washings of crude chrysene 1.2-Benzotluorene 2,3-Benzofluorene Pyrene Fluoranthene 3.4-Benzophenanthrene 1'-Methyl-1,Zbenzanthracene Triphenylene 1,2-Bensopyrene
From uetroleum ether washings of ciude chrysene From petroleum ether washings of crude chrysene From liquid part of cut (0'); fraction 220-230' / l o mm. From liquid part of cut (0'); fraction,l8Z0/4 mm. From liquid part of cut (0"); fraction 182'/4 mm. From liquid part of cut (0"); fraction 181-184'/4 mm.: maleic anhydride adduct From liquid part of cut (0'); fraction 194-198'/4 mm. From liquid part of cut (0'); fraction 265-278'/8 mm.
e
CHRYSENE FRACTION
(Boiling point, 190-275°/10 mm.) Physical Identification Remarks Constants M.p., 250' (from Mixed m.p.; trinitrobenzene compound ... tetrahydrom.p., 185' (66) naphthalene1 M.p., 158-159 Picrate: m.p., 141-142O; oxidation tu. quinone: m.p., 169-170'; trinitrobenzene adduct: m.p., 158" M.u., 190' 1,2-benzofluoren~ne: m.p., 132'; oxime: The mixtuie of the two isomers (111.p. 200') is difficult to separate (28,37) m.p., 200-202 2,3-benzofluorenone: m.p., 152'; oxime: M.p., 208-209" m.p., 231' (68) M.P., 149-15O0 Mixed m.p.; picrate: m.p., 222' ($0): trinitrobenaene adduct. m.p., 250' M.p., 100' Mixed m. green-blue color reaction with concd. kk04 (66):picrate: m.p., 183.5" Mixed m.p.; picrate: m.p., 128' M.p., 68' Spectrum. m.p., ~ S
M.p,, 196'
Mixed m.p.; picrate: m.p., 198'. speo- Calcd. for ClSHl?: C, 94.7; H. .5.3. Found: C, 94.7: H, 5.2 trum (B6) Picrate: m p 228O Calcd. for CzeHia- The d15icultly separable (17) mixture of the two hydrocarbons was isolate?: OINI: C,'64.9; H: 3.1; N, 8.7. Found: m.p 120°* picrate: m.p., 196-197 : C, 64 5; H, 3.2; N, 8.9 trin&obe&ene adduct: m.p., 244" Picrate: m.p., 197'. Found: C, 64.6 Separation: (17) H, 3.4; N, 8.9
From liquid part of cut (0"); M.p., 175'C fraction 265-278'/8 mm. Calcd. for CzsHiiOaN3: C, 65.9; H, 3.7. Found: C, 65.6; H, 3.6 The hydrocarbon does not give a stable picrate. Calcd. for CioHiz: C, 95.2; H, 4.8. Found: C, 95.0; H, 4.9.
Butadiene plays an important part in the thermal synthesis of the aromatic hydrocarbons. Thus, the methylated naphthalenes observed may owe their formation to the reaction between methylated dienes [the low fractions of the aromatization product contain isopentane derivatives (64)] and cyclohexene derivatives; but perhaps methylated, and therefore less aromatic, benzenes may be able to react with butadiene-e.g.,
Steiner (55) showed that the condensation of naphthalene and butadiene leads, in small yields, t o the system of phenanthrene, which is the prevalent constituent of the anthracene fraction, By successive reactions of the same type, phenanthrene and butadiene could give 1,a-bensanthracene (2,3-benzophenanthrene), triphenylene (9,10-benzophenanthrene), and picene (1,2,7,8-dibenzophenanthrene),and methylated dienes would lead to the methyl derivatives of such polycyclic systems. It is not surprising that the yield of anthracene is lower than that of phenanthrene. Thermodynamic comparison of the two hydrocarbons shows that the latter is more stable (47, 67). I t is also significant that a t 450' C. anthracene cracks 370 times more rapidly than phenanthrene (49). Orlow ( 4 6 )has shown that it is possible to interconvert the trTo three-nuclear hydrocarbons in the presence of copper and hydrogen. 3,4-Benzophenanthrene and lJ2-benzanthracene which occur in the aromatization product are possibly interconvertible in the same way. The diene rule is of value also for the explanation of the formation of other polycyclic hydrocarbons observed in the aromatieation product. The fluorene system is known to be formed from indene and butadiene (1,s). It is then not difficult to formulate the formation of 1,2- and 2,3-beneofluorene, thus:
[
+
trinitrobenzene
adduct:
Calcd. for CirHla: C, 94.2; Found: C, 94.0: H, 5.9
M.p., 138' (19)
3.4-Benzopyrene b
Vol. 43, No. 10
ODQ?~
H, 5,s.
which presumes that in analogy to indene, also 4,5- and 5,6beneindene should be formed a t least intermediarily, in the murse of the aromatization. Equally, fluoranthene may owe its occurrence t o a rcvwtion between acenaphthylene and butadiene:
Not only is it known that a t the temperature of the process acenaphthene is dehydrogenated to acenaphthylene (f?345),and that acenaphthylene has an unusually reactive double bond-for instance, in polymerization reactions (f8,13, 26, &)'-but it haP been shown experimentally (7,34)that acenaphthylene condensee easily a t temperatures of about 160" C. with dienes to hydrogenated fluoranthene derivatives. Another type of diene reaction which may play a part in the process considered here, is the condensation of vinyl aromatics with appropriate olefinic double bonds ( 2 , 6, 10, 16). Pyrene may be a tetrameriaation product of butadiene or a dimerization product of styrene:
(c=I=T
--+
__
A similar hypothesis, based on m-xylene, has recently been proposed by Baker, McOmie. and Norman (3). This presupposes a bimolecular dehydrogenation mechanisni Indeed, it is necessary to assume, and in accordance with experience, that a t the temperatures employed in the process aromatic hydrocarbons suffer such bimolecular dehydrogenation. An example is the observed occurrence of biphenyl and triphenylene, which appears regularly in the preparation of biphenyl from benzene (11). It is suggested that chrysene originates from a thermal reaction of indene, which has been known for a long time (64)and which the Dresent authors have shown to occur under their conditions in yields making this method the easiest way for the preparation [Hydrindene of the behaves tetracyclic similarly hydrocarbon. (36),] A 8
La-0:()3
the reaction involves the opening of thc fivemembered ring, it seemed probable that
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1951
other benzene derivatives containing a Ca side chain would react analogously. Indeed, allylbenzene gives chrysene a t 650” C. in a copper-packed tube in good yields; the reaction is accompanied by isomerization of allyl-to propenylbenzene, and by degradation to toluene.
This hypothesis is the attractive, as it makes the forOf the above-mentioned dibenzochrysene a8 the result of an analogous thermolysis of the 4,5-benzobdene which has been postulated as intermediate in the formation of 1,2-benzofluorene:
+
SUMMARY
A simple and consistent scheme has been offered for the mechanism of the formation of the polycyclic hydrocarbons isolated from the aromatization product. Although many of the constituents of the aromatization product are identical with typical components of the coal tar, the mechanism of their formation seems diametrically opposed in the two cases: first, the formation of coal tar is considered a degradation reaction (SI,46,6W)of the graphite structure of the high molecular coal; and secondly, the formation of the polycyclic hydrocarbons in the aromatization process is the result of a stepwise synthesis from low molecular units. ACKNOWLEDGMENT
The authors wish to thank Professor Leopold Ruaicka (Zurich) for his comparison of the picrates of the methylated naphthalenes with those of authentic samples and for samples of the corresponding styphnates. LITERATURE CITED
(1) Alder, K., and Rickert, H. F., Ber. deut. chem. Ges., 71, 379
(1938). (2) Bachmann, W. E., and Kloetzel, M. C., J . Am. Chem. Soc., 60, 2204 (1938). (3) Baker, W., McOmie, J. F W., and Norman, J. M., Chemistry & Industry, 1950, 77. (4) Bamberger, E., and Chattaway, F., Ann., 284, 61 (1895); Ber. deut. chem. Ges., 26, 1751 (1893). (5) Behr, A., and Dorp, A. van, Ann., 172, 265 (1874). (6) Bergmann, E., Bull. SOC. chim. France, 1948, D19. (7) Bergmann, E., Nature, 161, 889 (1948). (8) Bergmann, E., and Bergmann, F., J . Am. Chem. SOC.,60, 1805 (1938). (9) Bergmann, E., and Bergmann, F., J . Chem. Soc., 1939, 1019. (10) Bergmann, F., and coworkers, J . Am. Chem. Soc., 59, 1443 (1937); 62, 1699 (1940); 67, 1951 (1945). (11) Blum-Bergmann, O., Ibid., 60, 1999 (1938). (12) British Thomson-Houston Co., Ltd., Brit. Patent 598,857 (Feb. 27, 1948). (13) Cislak, F. E., U. 5. Patent 2,378,881 (June 19, 1945). (14) Cleaves, A. P.,Carver, M. S., and Hibbard, R. R., Natl. Advisory C m m . Aeronaut. Tech. Note, 1608, 22 pp. (1948). (15) Cohen, A,, and Warren, F. L., .T. Chem. SOC.,1937, 1315
2321
(16) Cook, J. PI., Ibid., 1931, 499. (17) Cook, J. W., Hewett, C. L.. and Hieger, I., Ibid., 1933, 395. (18) Cook J W., and Lawrence, C A,, Ibid., 1936, 1431. ! l ~ ,Cook, and Robinson, A, M,, Ibid., 1938, 505. (20) Coulson, E.A., Brit. Patent 555,981 (Sept. 15, 1943) (21) Coulson, E. A., J. Soc. Chem. Ind., 60, 123 (1941). (22) Du Pont de Nemours, E. I., & Co., and Walker, J. F., Brit. Patent 544,890 (May 1, 1942). (23) Dziewonski, K., and coworkers, Ber. deut. chem. Ges., 45, 2491 J.
(1912); 53, 2173 (1920). (24) Easterfield, T. H., and McClelland, N., Chemistry u: Industry, 42, 936 (1923). (25) Flowers, R. G., and Miller, H. F., J . Am. Chem. Soc., 69, 1388 (1947). (26) Fromherz, H.9 Thaler, L.7 and Wolf, G.9 2.Elektrochem., 49, 387 (1943). (27) Gavat, I., and Irimescu, I., Ber. deut. chem. Ges., 74,1812 (1941). (28) Graebe, C., Ann., 335, 136 (1904); Ber. deut. chem. Ges., 27, 952 (1874); 29, 826 (1896). (29) Haworth, R. D., Ann. Repts. o n Progress Chem., 34, 329 (1937). (30) Hintz, E., quoted by Fittig, R., and Gebhard, F., Ber. deut. chem. Ges., 10,2141 (1877). (31) I. G Farbenindustrie A.-G., Brit. Patent 435,254 (Sept. 9, 1935); Ibid., 470,338 (Aug. 9,1937); Ibid., 497,089 (Dec. 12, 1938); Ger. Patent 655,103 (Jan. 8, 1938); Ibid., 659,878 (May 12, 1938). (32) .Jones, H. O., and Wootton, H. A,, J . Chem. Soc., 91, 1146 (1907). (33) Kaufmann, H. P., and Baltes, J., Fette u. Seifen, 43, 93 (1936). (34) Kloetzel, M. C., and Mertel, H. E., J . Am. Chem. Soc., 72, 4786 (1950). (35) Kruber, O., Ber. deut. Chem. Ges , 57, 1008 (1924). (36) Ibid., 65, 1382 (1932.) (37) Ibid., 70, 1556 (1937). (38) Ibid., 72, 1972 (1939). 1391 Kruber. 0.. 2.anaew. Chem.. 53. 69 (1940). (40) Kruber, O., and Schade, W., Ber. deut. chem. Ges., 69, 1722 (1936). (41) Mair, B., et al., J . Research XVatl. B u r . Standards, 24, 395 (1940); 27, 39 (1941). (42) Miller, H. F., and Flowers, R. G. (to General Electric Co.), U. S. Patent 2,445,181 (July 13, 1948). (43) Morgan, G. T., and Coulson, E. A., J. SOC.Chem. Ind., 53, 73T (1939). (44) Nametkin, S. S., Pokrovskaqa, E. S., and Stepantseva, T . G., Doklady A k a d . N a u k S.S.S R.. 73, 715-17 (1950). (45) Neuworth, M. B., J . Am. Chem. Soc., 69, 1653 (1947). (46) Orlow, N. A., Ber. deut. chem. Ges., 60, 1950 (1927). (47) Parks, G. S., and Huffman, H. M., “Free Energies of Some Organic Compounds,” p. 90 ff., New York, Chemical Catalog Co., 1932. (48) Pascal, P., Bull. soc. chim. France, 29, 644 (1921). (49) Rosen, R., Oil Gas J., 39 (Feb. 20, 1941). (50) Ruzicka, L., et al., Helv. Ckim. Acta, 16, 314 (1933). (51) Ruzicka, L., and Ehmann, L., Ibid., 15, 140 (1932). (52) Scholl, R., and Meyer, K., Ber. deut. chem. Ges., 71, 407 (1938) (53) Sieglitz, A,, and Schatzkes, J., Ber. deut. chem. Ges., 54, 2070 (1921). (54) Spilker, A,, Ibid., 26, 1538 (1893). (55) Steiner, H., and Goodman, H., unpublished results. (56) Sudborough, J. J., J. Chem. Soc., 109, 1339 (1916). (57) Syrkin, Ya. K., and Dyatkina, M. E., Acta Physicochim. U.R.S.S., 21, 23 (1946). (58) Thiele, J., Ann., 376, 276 (1910). (59) Treibs, W., and Schmidt, H., Ber. deut. chem. Ges., 61,459 (1928) (60) Walker, J. F. (to E. I. dn Pont de Nemours & Co.), U.S. Patent 2,267,773 (Dec. 30, 1942). (61) Weissgerber, R., Be?. deut. chem. Ges., 41, 2913 (1908). (62) Weissgerber, R., Ger. Patent 301,079 (1917). (63) Weissgerber, R., and Kruber, O., Be?. deut. chem. Ges., 52, 346 (1919). (64) Weizmann, c.,et at., IND.EN^. CREM.,43, 2312 (1951). (65) Wichelhaus, H., Ber. deut. chem. Ges., 24, 3918 (1891). RECEIVED December 18, 1947. Contribution from the laboratories of The Weizmann Institute of Science, Rehovoth, Israel; Petrooarbon Ltd., London Bridge, London E.C. 4, England: and the Grosvenor Laboratory, 25 Grosvenor Crescent Mews, London S.W. 1, England,
