C8H6 Thermal Chemistry. 7-Methylenecyclohepta-1,3,5-dienyne (Heptafulvyne) by Flash Vacuum Thermolysis–Matrix Isolation. Chemical Activation in the Rearrangements of Phenylenedicarbenes and of Benzocyclobutadiene to Phenylacetylene

Arvid Kuhn; Daisuke Miura; Hideo Tomioka; Curt Wentrup

doi:10.1071/CH13670

RESEARCH ARTICLE

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C₈H₆ Thermal Chemistry. 7-Methylenecyclohepta-1,3,5-dienyne (Heptafulvyne) by Flash Vacuum Thermolysis–Matrix Isolation. Chemical Activation in the Rearrangements of Phenylenedicarbenes and of Benzocyclobutadiene to Phenylacetylene

Arvid Kuhn ^A , Daisuke Miura ^A , Hideo Tomioka ^B and Curt Wentrup ^A ^C

+ Author Affiliations

- Author Affiliations

^A School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia.

^B Mie University, Tsu, Mie 514-8507, Japan.

^C Corresponding author. Email: wentrup@uq.edu.au

Australian Journal of Chemistry 67(9) 1174-1179 https://doi.org/10.1071/CH13670
Submitted: 3 December 2013 Accepted: 6 January 2014 Published: 28 January 2014

Abstract

Methylenecycloheptadienyne 11 (heptafulvyne) is obtained very cleanly by flash vacuum thermolysis (FVT) of the diazobenzocyclobutene precursor 8 at 400°C followed by isolation as a neat solid at 77 K or in an Ar matrix at 7–10 K. Compound 11 is a yellow solid, stable till ~–100°C in the neat state. The diazo compound itself (2) is observable by IR spectroscopy following mild decomposition of the tosylhydrazone salt 1 at 115°C. FVT of 8 at 200°C also generates diazo compound 2 as observed by IR spectroscopy and on-line mass spectrometry. FVT of 8 at 600–800°C causes rearrangement of 11 to phenylacetylene 12 and benzocyclobutadiene 13. Mechanisms for the rearrangements are proposed. Facile rearrangement of benzocyclobutadiene to phenylacetylene is ascribed to chemical activation, which is also seen to be involved in the rearrangement of p-, m-, and o-phenylenebiscarbenes 25–27 to phenylacetylene 12.

References

[1] A. A. Frimer, J. Weiss, Z. Rosental, J. Org. Chem. 1994, 59, 2615.

[2] M. A. O’Leary, G. W. Richardson, D. Wege, Tetrahedron 1981, 37, 813.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL3MXltFGisL8%3D&md5=33f8896351f1cf5f60faa7baac3f17d7CAS |

[3] A. Nicolaides, T. Matsushita, K. Yonezawa, S. Sawai, H. Tomioka, L. L. Stracener, J. A. Hodges, R. J. McMahon, J. Am. Chem. Soc. 2001, 123, 2870.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXhsFKhtLc%3D&md5=6e2259c88ed2037c0e9b90f03f055e21CAS | 11456975PubMed |

[4] T. Jørgensen, C. T. Pedersen, R. Flammang, C. Wentrup, J. Chem. Soc., Perkin Trans. 2 1997, 173.
| Crossref | GoogleScholarGoogle Scholar |

[5] G. W. King, S. P. So, J. Mol. Spectrosc. 1970, 36, 468.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE3MXkslGgug%3D%3D&md5=82632565624b16f1af0a22c2aed14faeCAS |

[6] O. L. Chapman, C. C. Chang, N. R. Rosenquist, J. Am. Chem. Soc. 1976, 98, 261.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE28Xntl2mtw%3D%3D&md5=25da54ade553dcb5a8be72a71b3f7805CAS |

[7] M. J. S. Dewar, K. M. Merz, J. Am. Chem. Soc. 1985, 107, 6175.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2MXlslOks74%3D&md5=6c865aef1db5b707a4ab6ebcd9911705CAS |

[8] G. H. Mitchell, F. Sondheimer, J. Am. Chem. Soc. 1969, 91, 7520.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE3cXlsFSksA%3D%3D&md5=55ca535978069e586f41d2ff0974347fCAS |

[9] Enthalpy of formation of benzocyclobutadiene 97 ± 4 kcal mol^–1: K. M. Broadus, S. R. Kass, J. Am. Chem. Soc. 2000, 122, 10697.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXnt1Ois78%3D&md5=f4ed8cc6b14adba405f67cc105723f65CAS |

[10] Enthalpy of formation of phenylacetylene 73.3 ± 0.4 kcal mol^–1: NIST Database, Available at www.webbook.nist.gov (accessed 8 August 2013).

[11] P. Gerbaux, C. Wentrup, Aust. J. Chem. 2012, 65, 1655.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC38XhvVWgs7rK&md5=bac99f49f3c07172cdbcd36ae46f1662CAS |

[12] H. Dürr, H. Nickels, L. A. Pacala, M. Jones, J. Org. Chem. 1980, 45, 973.
| Crossref | GoogleScholarGoogle Scholar |

[15] M. Winkler, W. Sander, Aust. J. Chem. 2010, 63, 1013.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXosl2hs7c%3D&md5=72ce557dd56aba44956c69c6fa658c3eCAS |

[16] See C. Wentrup, Reactive Molecules 1984 (Wiley: New York, NY), and references therein.

[17] (a) J. A. Miller, S. J. Klippenstein, J. Phys. Chem. A 2001, 105, 7254. and references therein.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXkvFSjsLo%3D&md5=759f2e5b7501053691668ceda37db5ebCAS |
      (b) H. Hopf, G. Markopoulos, Beilstein J. Org. Chem. 2012, 8, 1936. and references therein.
         | Crossref | GoogleScholarGoogle Scholar |

[18] J. J. Gajewski, Hydrocarbon Thermal Isomerizations 2004, 2nd edn (Elsevier: San Diego, CA), and references therein.

[19] Enthalpies of formation are estimated using the method of C. Wentrup, Tetrahedron, 1974, 30, 1301. Thus ΔH_f⁰ of 24 = 153 and 26 ~175 kcal mol^–1 are derived.

[20] C. Wentrup, Aust. J. Chem. 2013, 66, 852.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3sXht1Ois7%2FF&md5=f54aae903c10e96e32e154fc80719227CAS |

[21] More precise activation energies for the reactions depicted in Scheme 5 may be obtained through quantum-chemical calculations. However, multiconfigurational methods will be required in order to treat open-shell diradical states correctly.

[22] M. W. Baum, J. L. Font, M. E. Meislich, C. Wentrup, M. Jones, J. Am. Chem. Soc. 1987, 109, 2534.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaL2sXhsFGkur4%3D&md5=6d10ef979e73e52c5160c2fdede375c6CAS |

[23] (a) S. Matzinger, T. Bally, E. V. Patterson, R. J. McMahon, J. Am. Chem. Soc. 1996, 118, 1535.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28Xmt1Gkuw%3D%3D&md5=208ff0b4f5c320907b43ef9a571efe88CAS |
      (b) M. W. Wong, C. Wentrup, J. Org. Chem. 1996, 61, 7022.
         | Crossref | GoogleScholarGoogle Scholar |
      (c) P. R. Schreiner, W. L. Karney, P. R. Schleyer, W. T. Borden, T. P. Hamilton, H. F. Schaefer, J. Org. Chem. 1996, 61, 7030.
         | Crossref | GoogleScholarGoogle Scholar |
      (d) C. M. Geise, C. M. Hadad, J. Org. Chem. 2002, 67, 2532.
         | Crossref | GoogleScholarGoogle Scholar |
      (e) M. J. Regimbald-Krnel, C. Wentrup, J. Org. Chem. 2013, 78, 8789.
         | Crossref | GoogleScholarGoogle Scholar |

[25] T. Mosandl, G. Macfarlane, R. Flammang, C. Wentrup, Aust. J. Chem. 2010, 63, 1076.
| Crossref | GoogleScholarGoogle Scholar |

[26] J. Brown, J. R. Flammang, Y. Govaert, M. Plisnier, C. Wentrup, Y. Van Haverbeke, Rapid Commun. Mass Spectrom. 1992, 6, 249.
| Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK38XitlCqtro%3D&md5=bc2b350c62bc4fce5171e4e5f8a1fd99CAS |

C8H6 Thermal Chemistry. 7-Methylenecyclohepta-1,3,5-dienyne (Heptafulvyne) by Flash Vacuum Thermolysis–Matrix Isolation. Chemical Activation in the Rearrangements of Phenylenedicarbenes and of Benzocyclobutadiene to Phenylacetylene

Abstract

References

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C₈H₆ Thermal Chemistry. 7-Methylenecyclohepta-1,3,5-dienyne (Heptafulvyne) by Flash Vacuum Thermolysis–Matrix Isolation. Chemical Activation in the Rearrangements of Phenylenedicarbenes and of Benzocyclobutadiene to Phenylacetylene