Unstable intermediates. Part LII. The reaction of tetracyanoethylene with dimethyl sulphoxide

Butler, R. N.; Oakes, J.; Symons, M. C. R.

doi:10.1039/j19680001134

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“…High temperatures are not appropriate for this reaction because the azole generated may undergo addition reactions with pbenzoquinone. 21 We also attempted the reaction with the non-metallic one-electron acceptor tetracycanoethylene, 22 but this gave no dearylation. A similar CAN oxidation of the tetrazole 4 gave p-benzoquinone and 5-phenyltetrazole 5.…”

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First generation of pentazole (HN5, pentazolic acid), the final azole, and a zinc pentazolate salt in solution: A new N-dearylation of 1-(p-methoxyphenyl) pyrazoles, a 2-(p-methoxyphenyl) tetrazole and application of the methodology to 1-(p-methoxyphenyl) pentazoleElectronic supplementary information (ESI) available: experimental details. See http://www.rsc.org/suppdata/cc/b3/b301491f/

2003

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First generation of pentazole (HN5, pentazolic acid), the final azole, and a zinc pentazolate salt in solution: A new N-dearylation of 1-(p-methoxyphenyl) pyrazoles, a 2-(p-methoxyphenyl) tetrazole and application of the methodology to 1-(p-methoxyphenyl) pentazoleElectronic supplementary information (ESI) available: experimental details. See http://www.rsc.org/suppdata/cc/b3/b301491f/

2003

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“…High temperatures are not appropriate for this reaction because the azole generated may undergo addition reactions with pbenzoquinone. 21 We also attempted the reaction with the nonmetallic one-electron acceptor tetracycanoethylene, 22 but this gave no dearylation. A similar CAN oxidation of the tetrazole 4 gave p-benzoquinone and 5-phenyltetrazole 5.…”

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First Generation of Pentazole (HN₅, Pentazolic Acid), the Final Azole, and a Zinc Pentazolate Salt in Solution: A New N‐Dearylation of 1‐(p‐Methoxyphenyl) Pyrazoles, a 2‐(p‐Methoxyphenyl) Tetrazole and Application of the Methodology to 1‐(p‐Methoxyphenyl) Pentazole.

2003

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Ceric ammonium nitrate (CAN) in methanol-water gave a new N-dearylation of a series of substituted 1-(p-methoxyphenyl) pyrazoles and a 2-(p-methoxyphenyl)tetrazole producing p-benzoquinone and the parent azole in a mole for mole ratio. Application of this reaction to 1-(p-methoxyphenyl) pentazole at 240 °C produced p-benzoquinone. 15 N NMR spectra suggest that pentazole, HN 5 , was also produced and held in solution as N 5 2 with Zn 2+ ion. The 15 N signal from N 5 2 was 210.0 ± 2.0 ppm in agreement with calculated values.The existence of an all-nitrogen aromatic azole ring, R-N 5 , the pentazoles, was proved by Clusius and Hurzeler 1 in Zurich and Huisgen and Ugi 2 in Munich. 3 Since then a significant goal of heterocyclic chemistry has been to prepare the parent pentazole, HN 5 . Ozonolytic degradation of the aryl ring was attempted 4 and recently revisited with controlled limited amounts of ozone, 5 but HN 5 or its anion N 5 2 was not found. Following the recent discovery of N 5 + as a reasonably stable cation in inorganic salts 6,7 there has been renewed experimental interest in allotropes of nitrogen and in N 5 2 in particular. There has also been much theoretical interest in these types of species. [8][9][10][11][12] Metallocene pentazole derivatives have been predicted as viable forms of N 5 2 , but bidentate forms MN 5 (M = Na, K, MgCl + , CaCl + ) and M(N 5 ) 2 (M = Na, K, Mg, Ca) and unidentate Zn(N 5 )Cl and Zn(N 5 ) 2 are calculated to have lower energy. 13 Recently it has been suggested the N 5 + .N 5 2 is a viable entity. 14 Following our recent establishment of the mechanism of formation of aryl pentazoles from aryldiazonium ions and azide ion, 15 we have been endeavouring to generate HN 5 and its anion N 5 2 . Recently N 5 2 has been detected for the first time from high voltage collisions of 4-pentazolylphenolate ion, N 5 -C 6 H 4 O 2 , in the mass spectrometer. 16 We are therefore prompted to make a preliminary report of our work.To remove an aryl group from an arylpentazole without destruction of the pentazole ring a mild oxidizing agent and the appropriate aryl pentazole must be chosen. Ceric (IV) ammonium nitrate (CAN) has been used to remove p-MeOC 6 H 5 -groups from p-methoxyphenyl ethers 17,18 and N-p-methoxyphenyl azetidines. [19][20] The methoxyphenyl ring is removed as p-benzoquinone and the use of H 2 18 O has proved that the two quinone oxygens arise from water in the solvent. 18 Successive one-electron oxidations are considered to produce a quinoneimine dication which is hydrolysed. 20 We tested this reaction for the first time with an azole substrate using the 1-N-pmethoxyphenyl pyrazole series shown in Fig. 1. It proved successful and was optimised at low temperatures. The pbenzoquinone is easily detected and estimated. Its presence indicates a mole for mole presence of the azole. High temperatures are not appropriate for this reaction because the azole generated may undergo addition reactions with pbenzoquinone. 21 We also attempted the reaction with the nonmetallic one-electron ...

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Sulfoxides and Sulfilimines

Ōae

1977

Organic Chemistry of Sulfur

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Unstable intermediates. Part LII. The reaction of tetracyanoethylene with dimethyl sulphoxide

Cited by 3 publications

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First Generation of Pentazole (HN₅, Pentazolic Acid), the Final Azole, and a Zinc Pentazolate Salt in Solution: A New N‐Dearylation of 1‐(p‐Methoxyphenyl) Pyrazoles, a 2‐(p‐Methoxyphenyl) Tetrazole and Application of the Methodology to 1‐(p‐Methoxyphenyl) Pentazole.

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Unstable intermediates. Part LII. The reaction of tetracyanoethylene with dimethyl sulphoxide

Cited by 3 publications

References 0 publications

First Generation of Pentazole (HN5, Pentazolic Acid), the Final Azole, and a Zinc Pentazolate Salt in Solution: A New N‐Dearylation of 1‐(p‐Methoxyphenyl) Pyrazoles, a 2‐(p‐Methoxyphenyl) Tetrazole and Application of the Methodology to 1‐(p‐Methoxyphenyl) Pentazole.

Sulfoxides and Sulfilimines

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First Generation of Pentazole (HN₅, Pentazolic Acid), the Final Azole, and a Zinc Pentazolate Salt in Solution: A New N‐Dearylation of 1‐(p‐Methoxyphenyl) Pyrazoles, a 2‐(p‐Methoxyphenyl) Tetrazole and Application of the Methodology to 1‐(p‐Methoxyphenyl) Pentazole.