Abstract
Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene–olefin coupling, which gives branched products—that is, secondary alkyl arenes—with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts—specifically ‘pincer’-ligated iridium complexes—and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.
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Wittcoff, H. A., Reuben, B. G. & Plotkin, J. S. Industrial Organic Chemicals 2nd edn (Wiley–IEEE, 2005).
Annual Energy Outlook 2010 With Projections to 2035 (US Energy Information Administration, 2010); see http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2010).pdf
Rueping, M. & Nachtsheim, B. J. A review of new developments in the Friedel-Crafts alkylation. From green chemistry to asymmetric catalysis. Beilstein J. Org. Chem. 6, No 6 (2010).
Olah, G. A., Reddy, V. P. & Prakash, G. K. S. in Kirk-Othmer Encyclopedia of Chemical Technology 5th edn, vol 12, 159–199 (Wiley, 2005).
Kocal, J. A., Vora, B. V. & Imai, T. Production of linear alkylbenzenes. Appl. Catal. A 221, 295–301 (2001).
Vora, B. V., Pujado, P. R., Imai, T. & Fritsch, T. R. Recent advances in the production of detergent olefins and linear alkylbenzenes. Tenside Surfact. Det. 28, 287–294 (1991).
Perego, C. & Ingallina, P. Recent advances in the industrial alkylation of aromatics: new catalysts and new processes. Catal.Today 73, 3–22 (2002).
Perego, C. & Ingallina, P. Combining alkylation and transalkylation for alkyl aromatic production. Green Chem. 6, 274–279 (2004).
Dry, M. E. Present and future applications of the Fischer-Tropsch process. Appl. Catal. A 276, 1–3 (2004).
Dry, M. E. The Fischer-Tropsch process: 1950–2000 Catal. Today 71, 227–241 (2002).
Smiešková, A., Rojasová, E., Hudec, P. & Šabo, L. Aromatization of light alkanes over ZSM-5 catalysts. Influence of the particle properties of the zeolite. Appl. Catal. A 268, 235–240 (2004).
Davis, B. H. Alkane dehydrocyclization mechanism. Catal. Today 53, 443–516 (1999).
Meriaudeau, P. & Naccache, C. Dehydrocyclization of alkanes over zeolite-supported metal catalysts: monofunctional or bifunctional route. Catal. Rev. Sci. Eng. 39, 5–48 (1997).
Davis, R. J. Aromatization on zeolite L-supported Pt clusters. Heterogen. Chem. Rev. 1, 41–53 (1994).
Arata, K., Hino, M. & Matsuhashi, H. Solid catalysts treated with anions. XXI. Zirconia-supported chromium catalyst for dehydrocyclization of hexane to benzene. Appl. Catal. A 100, 19–26 (1993).
Spitsyn, V. I., Pirogova, G. N., Korosteleva, R. I. & Kalinina, G. E. Aromatization of hexane and heptane on technetium catalysts. Doklady Akademii Nauk SSSR 298, 149–151 [Phys. Chem.] (1988).
Hino, M. & Arata, K. Solid catalysts treated with anions. Dehydrocyclization of hexane to benzene over zirconia-supported chromia. J. Chem. Soc. Chem. Commun. 1355–1356 (1987).
Isagulyants, G. V., Sterligov, O. D., Barkova, A. P., Mashinskii, V. I. & Kugucheva, E. E. Effect of modification of alumina-platinum catalysts on the composition of arenes formed in the process of dehydrogenation of higher n-paraffins. Neftekhimiya 27, 357–362 (1987).
Szebenyi, I. & Szechy, G. Acta. Chim. Hung. 98, 115 (1978).
Gairbekov, T. M., Takaeva, M. I., Khadzhiev, S. N. & Manovyan, A. K. Cracking and aromatization of C6–10 n-alkanes and n-alkenes by a zeolite-containing catalyst. J. Appl. Chem. USSR 64, 2396–2400 (1991).
Komarewsky, V. I. & Riesz, C. H. Aromatization of octane and decane in the presence of nickel-alumina catalyst. J. Am. Chem. Soc. 61, 2524–2525 (1939).
Vaisberg, K. S., Zhorov, Y. M., Panchenkov, G. M. & Rudyk, L. G. Formation of isomers of aromatic hydrocarbons during the dehydrocyclization of n-decane. Zh. Fiz. Khim. 44, 2630 (1970).
Shell. Dehydrocyclization of paraffins. NL patent 6715757 (1968).
Matsumoto, T., Taube, D. J., Periana, R. A., Taube, H. & Yoshida, H. Anti-Markovnikov olefin arylation catalyzed by an iridium complex. J. Am. Chem. Soc. 122, 7414–7415 (2000).
Oxgaard, J., Periana, R. A. & Goddard, W. A., III. Mechanistic analysis of hydroarylation catalysts. J. Am. Chem. Soc. 126, 11658–11665 (2004).
Foley, N. A., Lee, J. P., Ke, Z., Gunnoe, T. B. & Cundari, T. R. Ru(II) catalysts supported by hydridotris(pyrazolyl)borate for the hydroarylation of olefins: reaction scope, mechanistic studies, and guides for the development of improved catalysts. Acc. Chem. Res. 42, 585–597 (2009).
McKeown, B. A., Foley, N. A., Lee, J. P. & Gunnoe, T. B. Hydroarylation of unactivated olefins catalyzed by platinum(II) complexes. Organometallics 27, 4031–4033 (2008).
Luedtke, A. T. & Goldberg, K. I. Intermolecular hydroarylation of unactivated olefins catalyzed by homogeneous platinum complexes. Angew. Chem. Int. Ed. 47, 7694–7696 (2008).
Peng, Y., Ma, X. & Schobert, H. H. Thermopyrolysis mechanism of n-alkylbenzene: experiment and molecular simulation. Prepr. Am. Chem. Soc. Div. Pet. Chem. 43, 368–372 (1998).
Eapen, K. C., Snyder, C. E., Jr., Gschwender, L., Dua, S. S. & Tamborski, C. Poly-n-alkylbenzene compounds. A class of thermally stable and wide liquid range fluids. Prepr. Am. Chem. Soc. Div. Pet. Chem. 29, 1053–1058 (1984).
Huang, Z. et al. Efficient heterogeneous dual catalyst systems for alkane metathesis. Adv. Synth. Catal. 352, 125–135 (2010).
Huang, Z. et al. Highly active and recyclable heterogeneous iridium pincer catalysts for transfer dehydrogenation of alkanes. Adv. Synth. Catal. 351, 188–206 (2009).
Dobereiner, G. E. & Crabtree, R. H. Dehydrogenation as a substrate-activating strategy in homogeneous transition-metal catalysis. Chem. Rev. 110, 681–703 (2010).
Gupta, M., Hagen, C., Flesher, R. J., Kaska, W. C. & Jensen, C. M. A highly active alkane dehydrogenation catalyst: stabilization of dihydrido Rh and Ir complexes by a P-C-P pincer ligand. Chem. Commun. 2083–2084 (1996).
Gupta, M., Hagen, C., Kaska, W. C., Cramer, R. E. & Jensen, C. M. Catalytic dehydrogenation of cycloalkanes to arenes by a dihydrido iridium P-C-P pincer complex. J. Am. Chem. Soc. 119, 840–841 (1997).
Gupta, M., Kaska, W. C. & Jensen, C. M. Catalytic dehydrogenation of ethylbenzene and THF by a dihydrido iridium P-C-P pincer complex. Chem. Commun. 461–462 (1997).
Xu, W. et al. Thermochemical alkane dehydrogenation catalyzed in solution without the use of a hydrogen acceptor. Chem. Commun. 2273–2274 (1997).
Liu, F., Pak, E. B., Singh, B., Jensen, C. M. & Goldman, A. S. Dehydrogenation of n-alkanes catalyzed by iridium ‘pincer’ complexes. regioselective formation of alpha-olefins. J. Am. Chem. Soc. 121, 4086–4087 (1999).
Liu, F. & Goldman, A. S. Efficient thermochemical alkane dehydrogenation and isomerization catalyzed by an iridium pincer complex. Chem. Commun. 655–656 (1999).
Zhu, K., Achord, P. D., Zhang, X., Krogh-Jespersen, K. & Goldman, A. S. Highly effective pincer-ligated iridium catalysts for alkane dehydrogenation. DFT calculations of relevant thermodynamic, kinetic, and spectroscopic properties. J. Am. Chem. Soc. 126, 13044–13053 (2004).
Biswas, S. et al. in Abstracts of Papers, 235th ACS National Meeting, New Orleans, LA, United States INOR-302 (2008).
Haenel, M. W. et al. Thermally stable homogeneous catalysts for alkane dehydrogenation. Angew. Chem. Int. Ed. 40, 3596–3600 (2001).
Romero, P. E., Whited, M. T. & Grubbs, R. H. Multiple C-H activations of methyl tert-butyl ether at pincer iridium complexes: synthesis and thermolysis of Ir(I) Fischer carbenes. Organometallics 27, 3422–3429 (2008).
Doledec, G. & Commereuc, D. Synthesis and properties of homogeneous models of the Re2O7/Al2O3 metathesis catalyst. J. Mol. Cat. A 161, 125–140 (2000).
Jacobson, B. M., Arvanitis, G. M., Eliasen, C. A. & Mitelman, R. Ene reactions of conjugated dienes. 2. Dependence of rate on degree of hydrogen removed and s-cis or s-trans diene character. J. Org. Chem. 50, 194–201 (1985).
Garg, N. & Lee, T. R. Regioselective bromomethylation of 1,2-dialkylbenzenes. Synlett 310–312 (1998).
Acknowledgements
The authors are grateful to the National Science Foundation (grant no. CHE-0650456) for financial support for this work through the Center for Enabling New Technologies through Catalysis (CENTC).
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R.A., B.P., M.F., W.S., M.B. and A.S.G. conceived and designed the experiments; R.A., B.P., M.F. and C.S. performed the experiments; R.A., B.P., M.F., C.S., M.B. and A.S.G. co-wrote the paper.
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Ahuja, R., Punji, B., Findlater, M. et al. Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes. Nature Chem 3, 167–171 (2011). https://doi.org/10.1038/nchem.946
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DOI: https://doi.org/10.1038/nchem.946
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