J O U R N A L OF T H E AMERICAN CHEMICAL S O C I E T Y VOLUME 67
OCTOBER 17, 1945
[CONTRIFiUTION FROM THE RESEARCH
LABORATORIES OF THE UNIVBRSAL
NUMBER 10 OIL PRODUmS COMPANY ]
Reaction of Methylcyclopentane with Olefins in the Presence of Sulfuric Acid and Hydrogen Fluoride Catalysts' BY HERMAN PINESAND V. N. IPATIEPP The study of the reaction of cycloparaffins with olefins was undertaken in order to gain a better understanding of the alkylation reactionP because the ring hydrocarbons readily can be detected and identified. For this study methylcyclopentane*was chosen as the hydrocarbon to be alkylated in preference to the more accessible cyclohexane, for the reason that it undergogs alkylation more readily and a t the same time permits the observation of whether or not the conversion of the cyclopentane to cyclohexane ring occurs. It is known that a t room temperature the equilibrium is mostly toward the cyclohexane side.' Alkylation with the following olefins was investigated : n-butenes, isobutylene, 2-pentene, 3-methyl-l-butene, and a mixture of 2,4,4-trimethyl-l-penteneand 2,4,4-trimethyl-2pentene. The alkylations were carried out in the presence of sulfuric acid and hydrogen fluoride, because these two catalysts, under the experimental conditions used, cause practically no isomerization of saturated hydrocarbons. Reaction of methylcyclopentane with olefins apparently involves: (a) addition of methylcyclopentane to olefins accompanied by ring wpansion and migration of alkyl groups within the ring; (b) hydrogen disproportionation, the naphthenes being usually the hydrogen donors, (1) Preaented before the meeting of the Petroleum Division of the American Chemical Society in Cleveland, April, 1944. (2) (a) V. N. Ipatieff nnd A. V. Gr-, THn JOUBNAL, ET, 1616 (1936); (b)V. N.Iwtieff, A. V. Gmue, H. P i n u nnd V. 1. Komarena b , ibid., 66,913(€936);(c) H.Pines, A. V. Groue and V. N. Ipatic5, ibid., M,33 (1942); (d) 5. H. McAlhter, J. Anderson, S. A. Ballard and W.E. Rou, J . Or#. Ckim., e, 047 (1941); (e) S. F. Birch, A. E. Dustan, F. A. Fidtu, F. B. Pim nnd T. Tait, I d . Ene. C h a . , 81, 1079 (1939). (3) € Pines I. and V. N. Ipatieff (to U n i v v u t Oil Products Co.), U. S. Patent9 2,291,264 (July 28, 1942) and 2,316,078 (March 80, 1943). (4) H.Pin- and V. N Ipatieff. Tar8 Jon.ar*~. el, 1076 (1939).
whereas the olefins are the hydrogen acceptors; (c) isomerization of straight-chain olefins to isoolefins followed by hydrogenation; (d) interreaction of partially dehydrogenated naphthenes to form polycyclic olefinic or polycyclic saturated hydrocarbons; (e) depolymerization and/or depolyalkylation.' The ease With which the abovementioned reactions occur depends to a great extent upon the olefins used. The unsaturated hydrocarbons formed during the reaction are usually found in the catalyst layer, from which they can be recovered by diluting it with water. In the hydrogen fluoride catalyzed reactions where the catalyst is removed by evaporation, the olefinic hydrocarbons as such or in the form of fluorides are separated from the saturated hydrocarbons by treating with sulfuric acid and diluting with water. The structures of the various compounds obtained were determined by physical constants, elementary analysis, and conversion of the naphthenes to the corresponding aromatic hydrocarbons which can be readily converted to known derivatives. Discussion of Results Sulfuric Acid Catalyzed A&ylation.-The reaction was carried out by contacting 3.0 moles of methylcyclopentane with 2.25 moles of olefins in the presence of 3 moles of 100% sulfuric acid. Most of the experiments were carried out at 1017' With a contact time of two hours. The two layers which were formed were separated and investigated. The summary of the experimental data and results 3s given in Table I. n-Butenes.-The major part of the products formed resulted from the reaction of 1 mole of (6)(a) V. N. Ipntieff and H. Pines, Ind. En#. Chum., ST, 1364 (1936); (b) J . Or#. Chm., 1, 464 (1936): (c) Tam JOURNAL. 68, inna (igsn).
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HERMANPINESAND V. N. IPATIEPP
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Vol. 67
TABLE I Experiment X o ~ i 2 3 4 I ti Methylcyclopentane, g. 253 252 252 252 252 252 Reactants Olefins (kind) Butenes Butenes Isobutylene 2-Peiitene ;3-51ethyl-l-buturir 1)lis h ~ t y l c n e s 157 157 126 126 126 121 Olefins, g. 275 273 274 275 270 274 Sulfuric acid, loo%, g. 10-14 10 16 10-15 10-17 10-17 40-47 :: j 2.0 -3 2 0 2.0 2.0 Products recovered 303c 340d 327 is 17' 324" 313b Hydrocarbon layer, g. 323 3 52 335 338 306 33 1 Catalyst layer, g. , 5 5 1 15 8 Mechanical losses Distn. of methylcyclopentane in reaction product, mole % 3s 3 49 2 33.3 59.0 58.3 35.0 Methylcyclopentane recovered 7 ti 7.8 ,i.6 2.7 27.7 14.3 As alkyl monocyclic 13. 1; 20. C) 1(J. 0 6.0 25.3 20 7 As dicyclic (ClrH2~jff 5.3 3 0 2 7 3.3 2.3 As alkyl dicyclicg 10 0 7.0 .. 7.3 5.3 AS poiycyclich 11.7 28.3 26.7 17.0 19 6 111catalyst layer Llistn. of olefins, mole 28.4' .. 15.5' 24.0 36.8' 19.6" .4s corres. paraffins 17.7 + 3 ,2 ' 1.0 15 5 24 0 25 8 As hydrogenated tlimers' 10.2 19 2 :i. x 36.8 19.0 8 9 As alkyl monocyclic 4.5 1.7 7.9 1 3 As alkyl dicyclic 28, 2 36 5 36.8 57.7 47.0 13 3 In catalyst layer See Fig. 1 for distillation curve. See Fig. 2. See Fig. 3. See Fig. 4. e See Fig. 5. See Fig. 6. u CalcuPolycyclic lated on the basis of 2 moles of methylcyclopentane reacting to produce 1 mole of dicyclic hydrocarbons. Not determined. j Contains 15% of isobutanr. hydrocarbons containing more than two rings per molecule. Consists of isopentane. I n addition to the 36.8 mole % of isopentane found, there was also 10.7 mole (& of isobutane. Consists of dodecanes. Calculated on t h c basis of Of the diisobutylene, 4.5 mole yo was converted to isobutane. 2 moles of olefins reacting to produce 1 mole of hydrogenated dimer.
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I
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'
butenes with 1 mole of methylcyclopentane; 1,3dimethyl-5-ethyl- and 1,3-dimethyl-4-ethyIcyclohexane accounted for 83% of the methylcyclopentane which reacted. The structure of the dimethylethylcyclohexanes formed was determined by converting the products, by means of dehydrogenation, to the corresponding aromatics4 and converting the latter by means of oxidation
with dilute nitric acid at atmospHeric or superatmospheric6 pressure or by means of bromination to known solid derivatives. Alkylcyclopentanes under similar conditions did not undergo dehydrogenation. The hydrocarbon layer also contained minor
30 50 70 90 L-olume per cent. distilled. Fig. 3 -hlethylcyclopentane n-butenes at 40-47'. 10
10 30 50 70 90 Volume per cent. distilled. Fig. 1.-Methylcyclopentane n-butenes at 10-17*
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