Notiz zur Struktur eines „2.4.6‐Tri‐tert.‐butyl‐phenylhydrazins”︁

Rieker, Anton; Niederer, Paul

doi:10.1002/cber.19691021138

Cited by 3 publications

(1 citation statement)

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“…In addition, formation of an aryne (via 2) is blocked unless there is extrusion of a tert-butyl cation which would be de- tected by product analysis. Such dealkylations may account for anomalies previously reported in the aqueous acid diazotizations of 2,4,6-tri-tert-butylaniline (14). We are investigating the unusual reactivity in dediazoniation of 1 and, with the above features in mind, have undertaken an exploratory study on the esr and product studies from 1.…”

Section: Introductionmentioning

confidence: 94%

Sterically hindered aromatic compounds. IX. Electron spin resonance and product studies of the dediazoniation reaction

Barclay¹,

Briggs²,

Briggs³

et al. 1979

Can. J. Chem.

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Can. J. Chem. 57,2 172 (1979). An esr study of the dediazoniation of 2,4,6-tri-tert-butylaniline with butyl nitrite in methylene chloride indicated the formation of the 2,4,6-tri-tert-butylphenyl radical which was spin trapped by the butyl nitrite. The persistent 2,4,6-tri-tert-butylphenoxy radical was also formed. Product studies from reactions catalyzed by pivalic acid indicate a novel rearrangement of an orthotert-butyl group under dediazoniation conditions forming such products as: 3-(3,5-di-tertbutylpheny1)-2-methylpropene (4), 1-(3,5-di-tert-butylpheny1)-2-methylpropen (5), 3-(33-ditert-butylpheny1)-2-methyl-2-propanol (6), 3-(3,5-di-tert-butylphenyl)-2-butoxy-2-methylpropane (7), 3-(3,5-di-rerr-butylphenyl)-2-methyl-2-trimethyacetoxypropane (8), 2,4,6-tri-terrbutylphenyl trimethylacetate (9), and 2,4,6-tri-tert-butyl-1,4-quinol (10). The major products (47) are accounted for by a free radical pathway by rearrangement of the 2,4,6-tri-rerr-butylphenyl radical. The minor products (esters 8 and 9) probably form by competing ionic reactions. N-Nitroso-2,4,6-tri-tert-butylacetanilide decomposes (at least in part) by a radical pathway leading to the rearranged radical (cH~),&ZH,-A~ which was spin trapped by the nitroso group of the substrate. Spin trapping experiments during the dediazoniation of 2,5-di-rerrbutylaniline similarly gave evidence for the formation of aryl radicals. Une Ctude rpe de la dediazotation de la tri-rert-butyl-2,4,6 aniline avec le nitrite de butyle en solution dans le chlorure de mkthyle indique qu'il y a formation du radical tri-terr-butyl-2,4,6 phenyle dont le spin est piige par le nitrile de butyle. Il y a aussi formation du radical tri-rert-butyl-2,4,6 phenoxyle. Une Ctude des produits formes lors de reactions catalysees par I'acide pivalique indique qu'il se produit, dans les conditions de didiazotation, une nouvelle transposition d'un groupe ortho rert-butyle conduisant a la formation des produits suivants:(di-tert-butyl-3,5 phCny1)-3 methyl-2 propkne (4), (di-tert-butyl-3,5 phCny1)-l methyl-2 propene (5), (di-tert-butyl-3.5 phCny1)-3 methyl-2 propanol-2 (6), (di-tert-butyl-3,5 phenyl)-3 butoxy-2 methyl-2 propane (9, (di-terr-butyl-3,5 phenyl)-3 methyl-2 trimethylacCtoxy-2 propane (8), trimethylacitate de tri-rert-butylphCny1e-2,4,6 (9) et tri-tert-butyl-2,4,6 quinol-1,4 (10). On peut expliquer la formation des produits principaux (47) a I'aide du chemin rtactionnel radicalaire impliquant une transposition du radical tri-rert-butyl-2,4,6 phenyle. Les produits mineurs (esters 8 et 9) se forment probablement par des reactions ioniques en competition. Le N-nitroso tri-terr-butyl-2,4,6 acetanilide se decompose (au. moins en partie) par un mecanisme ridicalaire conduisant au radical transpose (CH3),CCHZ-Ar dont le spin est pikg6 par un groupe nitroso du substrat. Des experiences de piegeage de spin au cours de la didiazotation de la di-tert-butyl-2,5 aniline fournissent des donnees relatives a la formation de radicaux aryles.[Traduit par le journal]

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Section: Introductionmentioning

confidence: 94%

Sterically hindered aromatic compounds. IX. Electron spin resonance and product studies of the dediazoniation reaction

Barclay¹,

Briggs²,

Briggs³

et al. 1979

Can. J. Chem.

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ChemInform Abstract: STRUKTUR EINES ′2,4,6‐TRI‐TERT.‐BUTYL‐PHENYLHYDRAZINS′

Rieker¹,

Niederer²

1970

Chemischer Informationsdienst. Organische Chemie

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Bei der Diazotierung des Anilins (II) mit Na‐nitrit in wäßrig‐salzsaurem Eisessig und anschließender Reduktion des intermediären Diazoniumsalzes mit wäßriger Na‐hydrogensulfit‐Lösung entstehen neben ca. 20% Chlorbenzol (IIIa), wenig Phenylacetat (IIIb), 4‐Nitro‐2,6‐di‐tert.‐butyl‐anilin und weiteren unbekannten Substanzen 10‐20% einer als Hydrochlorid isolierten Verbindung, der aufgrund von NMR‐ und Massenspektraldaten sowie unabhängiger Synthese aus 3,5‐Di‐tert.‐butyl‐toluol oder ‐brombenzol die Struktur (IV) zukommt.

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