Matrix Studies on Aromatic and Heteroaromatic Nitrenes and their Rearrangements

Wentrup, Curt

doi:10.1002/9781118560907.ch8

Cited by 9 publications

(10 citation statements)

References 92 publications

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“…The matrix photochemistry of several hetarylcarbenes and the isomeric (het)arylnitrenes has been reviewed recently, and it has been established that nitrenes are generally thermodynamically more stable than the isosteric carbenes . The rearrangement of 4-pyridylcarbene 1 to 3-pyridylcarbene 3 to 2-pyridylcarbene 6 and finally to phenylnitrene 8 has been investigated in great detail (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Rearrangements of 4-Quinolylcarbene, 3-Quinolylcarbene, and 2-Quinolylcarbene to 1-Naphthylnitrene and Cyanoindenes by Falling Solid Flash Vacuum Pyrolysis

et al. 2016

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The relationship between 4-quinolylcarbene 17, 3-quinolylcarbene 21, 2-quinolylcarbene 25, and 1-naphthylnitrene 35 has been explored experimentally and computationally. The diazomethylquinolines generated from (5-tetrazolyl)quinolines or 1,2,3-triazolo[1,5-a]quinoline by conventional flash vacuum pyrolysis (FVP) were observed by IR spectroscopy. The carbenes were generated by falling solid flash vacuum pyrolysis (FS-FVP). 4-Quinolylcarbene 17 was found to rearrange to 3-quinolylcarbene 21 and then to 2-quinolylcarbene 25, and finally via 1-naphthylnitrene 35 to 1-cyanoindene 36, which then isomerizes to 3- and 2-cyanoindenes 12 and 13. The thermal rearrangement of 2-quinolylcarbene to 1-naphthylnitrene was verified by ESR spectroscopy. The reaction mechanism has been elucidated with the help of calculations of the structures and energies of the quinolylcarbenes and 1-naphthylnitrene and the intervening aza-benzobicyclo[4.1.0]heptatrienes, aza-benzocycloheptatetraenes, and aza-benzocycloheptatrienylidenes and the transition states connecting them at the B3LYP/6-31G* level. The nonobserved 1,2-hydrogen shifts in aza-benzocycloheptatetraenes/aza-benzocycloheptatrienylidenes are found to have very high activation barriers.

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Section: Introductionmentioning

confidence: 99%

Rearrangements of 4-Quinolylcarbene, 3-Quinolylcarbene, and 2-Quinolylcarbene to 1-Naphthylnitrene and Cyanoindenes by Falling Solid Flash Vacuum Pyrolysis

et al. 2016

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“…Ring expansion, ring opening and ring contraction reactions are ubiquitous in aromatic and heteroaromatic nitrene chemistry [20,21]. Loss of N2 from 1,5-disubstituted tetrazoles 21 will in principle lead to (singlet) imidoylnitrenes 22 (Scheme 4), which are know to rearrange to carbodiimides 23 [4,10,22].…”

Section: Discussionmentioning

confidence: 99%

“…The results presented above indicate that the carbodiimides 14 and 18 are observable reactive intermediates. The formation of cyanamides, when it happens at all, may take place via ring opening of either the nitrenes 32 and 34 or the carbodiimides 14 and 18 to biradicals followed by recyclization [20,21]. [20,21,25].…”

Section: Discussionmentioning

confidence: 99%

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Pyrolysis of annelated hexa- and heptamethylene-tetrazoles: Formation of 9- and 10-membered cyclic carbodiimides

Wentrup

Vosswinkel

2016

Journal of Analytical and Applied Pyrolysis

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Please cite this article as: Curt Wentrup, Michael Vosswinkel, Pyrolysis of annelated hexa-and heptamethylene-tetrazoles, Journal of Analytical and Applied Pyrolysis http://dx.doi.org/10.1016/j.jaap. 2015.11.013 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Flash vacuum pyrolysis of 8-and 9-membered polymethylenetetrazoles is reinterpreted.The products are 9-and 10-membered cyclic carbodiimides rather than cyanamides.

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“…At the ANU, and later at the universities of Lausanne, Marburg, and Queensland, I was able to undertake a long series of investigations of the FVP of aryl azides, [75,76] and in particular to discover the ring contraction and ring expansion of phenylnitrene 2 to cyanocyclopentadiene 3 and azacycloheptatetraene 6 (Scheme 14). [77] As we now know, these same processes are energetically very favourable in the radical cations in the mass spectrometer and therefore responsible for the generation of the strong m/z 91 (C 6 H 5 N þ ) signal on electron impact of phenyl azide 1, triazolopyridne 4, phenyl isocyanate, and several other precursors.…”

Section: Azidesmentioning

confidence: 99%

Nitrogen- and Sulfur-Containing Energetic Compounds. 64 Years of Fascinating Chemistry

Wentrup¹

2019

Aust. J. Chem.

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This essay details the author’s work with high-energy molecules based on sulfur or nitrogen, or both, which started with amateur rocket propellants like zinc dust and sulfur followed by experiments with the highly sensitive compounds nitrogen trichloride and fulminating gold. Research on the inorganic and organic fulminates and the isomeric cyanates led to detailed investigations of reactive intermediates generated by flash vacuum pyrolysis or photolysis, in particular nitrenes and carbenes derived from azides, diazo compounds, triazoles, and tetrazoles and characterized in low temperature matrices.

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Matrix Studies on Aromatic and Heteroaromatic Nitrenes and their Rearrangements

Cited by 9 publications

References 92 publications

Rearrangements of 4-Quinolylcarbene, 3-Quinolylcarbene, and 2-Quinolylcarbene to 1-Naphthylnitrene and Cyanoindenes by Falling Solid Flash Vacuum Pyrolysis

Rearrangements of 4-Quinolylcarbene, 3-Quinolylcarbene, and 2-Quinolylcarbene to 1-Naphthylnitrene and Cyanoindenes by Falling Solid Flash Vacuum Pyrolysis

Pyrolysis of annelated hexa- and heptamethylene-tetrazoles: Formation of 9- and 10-membered cyclic carbodiimides

Nitrogen- and Sulfur-Containing Energetic Compounds. 64 Years of Fascinating Chemistry

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