Open-chain nitrogen compounds. Part II. Preparation, characterization, and degradation of 1(3)-Aryl-3(1)-methyltriazenes; the effect of substituents on the reaction of diazonium salts with methylamine

1977 ◽  
Vol 55 (10) ◽  
pp. 1701-1709 ◽  
Author(s):  
T. Patrick Ahern ◽  
Handrick Fong ◽  
Keith Vaughan
Keyword(s):  
Degradation Products ◽  
Diazonium Salt ◽  
Diazonium Salts ◽  
Nitrogen Compounds ◽  
Open Chain ◽  
Effect Of Substituents ◽  
Electron Withdrawing Group

Treatment of the diazonium salts, X•C6H4N2+, with aqueous methylamine affords good yields of the monomethyltriazenes, X•C6H4•N=N•NHMe, when the substituent is a strongly electron-withdrawing group (X = o-, m-, and p-NO2; o-, m-, and p-CO2R; p-CN and p-COCH3). Preparation of the triazene from the p-bromobenzene diazonium salt was accompanied by formation of a pentaazadiene. Monomethyltriazenes were not obtained when diazonium salts containing other substituents (X = H, p-CH3, o-CF3, p-Cl, p-F, p-NMe2, p-OH, p-OCH3, p-Ph, p-NHCOCH3) were treated with methylamine. In these cases the products were either pentaazadiene, or 1,3-diaryltriazenes or unstable materials. The monomethyltriazenes vary considerably in stability and give rise to a number of different degradation products, which were either diaryltriazenes or 3-alkyl-1,3-diaryltriazenes or simply arylamines. 1(3)-(p-Nitrophenyl)-3(1)-methyltriazene was found to be a moderately effective methylating agent.

Open-chain nitrogen compounds. Part III. The formation of triazenes in the reaction of diazonium salts with α-aminoacetonitrile and related α-substituted alky lamines

1977 ◽  
Vol 55 (21) ◽  
pp. 3751-3754 ◽  
Author(s):  
Theresa A. Daniels ◽  
Shiraz Sidi ◽  
Keith Vaughan
Keyword(s):  
Aqueous Solution ◽  
Diazonium Salt ◽  
Diazonium Salts ◽  
Nitrogen Compounds ◽  
Open Chain ◽  
Diazonium Ion ◽  
Methylene Group

Several triazenes of type Ar•N==N•NH•CH2Y, where Y is electron withdrawing, have been prepared by reaction of the diazonium salts X•C6H4N2+ (X = H, p-NO2, p-CO2Me, p-COPh, and o-COPh) with the α-substituted alkylamines NH2CH2Y (Y = CN, CO2Et, COPh, and CH(OCH3)2) in aqueous solution, without prior isolation of the diazonium salt. In all cases, the diazonium ion attacks at the NH2 moiety exclusively and the methylene group in NH2CH2Y shows no tendency to compete for the diazonium ion.

Open chain nitrogen compounds. Part X. Thermolysis of α-diazoacetanilides in methanol: a convenient synthesis of α-methoxyacetanilides from ethyl N-(arylazo)glycinate

1986 ◽  
Vol 64 (4) ◽  
pp. 799-802
Author(s):  
Kumudini U. K. Gamage Nicholas ◽  
Keith Vaughan
Keyword(s):  
Tertiary Amine ◽  
Methanol Solution ◽  
Small Scale ◽  
Nitrogen Compounds ◽  
Rare Type ◽  
Open Chain ◽  
Amide Derivative ◽  
Convenient Synthesis ◽  
Synthetic Equivalent ◽  
Electron Withdrawing Group

α-Diazoacetanilides (4), which are readily available from the open-chain triazenes (2), undergo thermolysis in methanol solution to afford the α-methoxyacetanilides (5), an apparently rare type of ether/amide derivative. The methanolic thermolysis is inhibited by the presence of a tertiary amine in the solvent, suggesting that a carbocation, rather than a carbene, intermediate is involved in the conversion of the diazo-amide to the methyl ether. This hypothesis is supported by the retardation of the reaction in the presence of an electron-withdrawing group in the para position of the anilide. The conversion 4 → 5 was also observed, on a small scale, under photolytic conditions. It is suggested that the α-diazoacetanilide represents a useful synthetic equivalent for the synthon ArNHCOCH2+.

Open-chain nitrogen compounds. Part V. Hydroxymethyltriazenes: synthesis of some new alkyl homologues of the anti-tumour 3-methyl-3-hydroxymethyltriazenes and preparation of the derived acetoxymethyl-, benzoyloxymethyl-, and methoxymethyltriazenes

1984 ◽  
Vol 62 (4) ◽  
pp. 741-748 ◽  
Author(s):  
Chantal M. Hemens ◽  
Hartford W. Manning ◽  
Keith Vaughan ◽  
Ronald J. LaFrance ◽  
York Tang
Keyword(s):  
Benzoyl Chloride ◽  
Diazonium Salt ◽  
Nitrogen Compounds ◽  
Ortho Position ◽  
The Novel ◽  
Ethanolic Solution ◽  
Ether Linkage ◽  
Open Chain ◽  
Diazonium Ions ◽  
Derivatives Of

The synthesis of some new 1-aryl-3-alkyl-3-hydroxymethyltriazenes is described. The method of coupling a diazonium salt with an alkylamine/formaldehyde mixture has been extended to (a) some diazonium ions with para substituents other than—M groups, (b) those with substituents in the ortho position, and (c) to homologous alkylamines (e.g. ethylamine, propylamine, etc.). Hydroxymethyltriazenes can also be prepared by the reaction of a 1-aryl-3-methyltriazene with formaldehyde. Several new derivatives of the hydroxymethyl function have been prepared. Reaction with acetic anhydride or benzoyl chloride in pyridine affords respectively the acetoxymethyl- and benzoyloxymethyl-triazenes; the acetates and benzoates react readily with methanol to give the novel methoxymethyltriazenes. This is the first report of a series of dialkyltriazenes with an ether linkage in the α position. An ether of this type has also been obtained directly from the diazonium fluoroborate salt by coupling with a mixture of benzylamine and formaldehyde in ethanolic solution.

Reactions of 2-(benzimidazol-2-yl)acetonitrile and its N-ethoxycarbonyl derivative with some azol-3-diazonium salts

1984 ◽  
Vol 49 (1) ◽  
pp. 275-279 ◽  
Author(s):  
Jan Slouka ◽  
Vojtěch Bekárek
Keyword(s):  
Diazonium Salt ◽  
Ethyl Chloroformate ◽  
Diazonium Salts

Coupling of 2-(1-ethoxycarbonyl-benzimidazol-2-yl)acetonitrile (II) with 5-methylpyrazol-3-diazonium (IIIa) or indazol-3-diazonium salt (IIIb) does not give the corresponding derivatives VIIa, VIIb of pyrazolo[3,2-c]-1,2,4-triazine but, instead, gives the corresponding 2-(3-azolyl)-1-oxo-1,2-dihydro-1,2,4-triazino-[4,5-a]benzimidazole-4-carbonitriles VIIIa, VIIIb. Coupling of 2-(benzimidazol-2-yl)acetonitrile (I) with the diazonium salt IIIa gives 7-amino-6-(benzimidazol-2-yl)-2-methylpyrazolo[3,2-c]-1,2,4-triazine (VIa) which, on reaction with ethyl chloroformate, undergoes cyclization to 2-methyl-12,13-dihydropyrazolo[3",2":3',4']-1,2,4-triazino[5',6':6,5]-pyrimido[3,4-a]benzimidazol-12-one (IXa). The compound VIa and 1-amino-2-(benzimidazol-2-yl)-1,2,4-triazono[4,3-b]indazole (VIb) are also formed by recyclization of the compounds VIIIa and VIIIb, respectively, in boiling aqueous pyridine.

scholarly journals AROMATIC SUBSTITUTION: PART IX. ON THE MECHANISM OF THE PSCHORR CYCLIZATION

1965 ◽  
Vol 43 (4) ◽  
pp. 940-949 ◽  
Author(s):  
R. A. Abramovitch ◽  
G. Tertzakian
Keyword(s):  
Acid Solution ◽  
Diazonium Salt ◽  
Equimolar Mixture ◽  
Diazonium Salts ◽  
Aromatic Substitution ◽  
Radical Process ◽  
Aqueous Acid Solution ◽  
Aqueous Acid ◽  
Catalyzed Reactions

The decomposition of the diazonium salt from 3-(o-aminobenzoyl)pyridine has been studied under various conditions. A competitive-type cyclization of an equimolar mixture of the diazonium salts of 2-aminobenzophenone and 2-amino-3′-nitrobenzophenone has also been carried out. The results are interpreted in terms of a radical process in the copper-catalyzed reactions. It is suggested that the uncatalyzed thermal decompositions in aqueous acid solution give rise to a diradical cation intermediate in equilibrium with the aryl cation.

Open-chain nitrogen compounds. Part XV. A kinetic study of the hydrolysis of 1-aryl-3-aryloxymethyl-3-methyltriazenes and related triazenes

1992 ◽  
Vol 70 (8) ◽  
pp. 2224-2233 ◽  
Author(s):  
Keith Vaughan ◽  
Donald L. Hooper ◽  
Marcus P. Merrin
Keyword(s):  
Rate Constant ◽  
Order Rate Constant ◽  
Buffer System ◽  
Open Chain ◽  
Nucleophilic Displacement ◽  
Ether Oxygen ◽  
Rate Of Hydrolysis ◽  
Electron Withdrawing Group ◽  
Ph Range ◽  
Kinetics Of

The kinetics of hydyrolysis of a series of 1-aryl-3-aryloxymethyl-3-methyltriazenes, Ar-N=N-NMe-CH2OAr′, was studied over the pH range 2–7.5. Reactions were followed by the change in UV absorbance spectra of the triazenes. The aryloxymethyltriazenes decompose more slowly at pH 7.5 than the hydroxymethyltriazenes, Ar-N=NMe-CH2OH; the hydrolysis is favoured by the presence of an electron-withdrawing group in Ar′. A mixed isopropanol/buffer system was developed in order to improve solubility of the aryloxymethyl triazenes. Lowering the pH caused an increase in the rate of hydrolysis and under strongly acidic conditions an electron-withdrawing group in Ar′ actually slows down the reaction. A Hammett plot of the pseudo-first-order rate constant, kobs, is curved, indicating that two or more mechanisms operate simultaneously and that the contribution of each mechanism is substituent-dependent. A plot of kobs vs. [buffer] is linear; the slope of the plot affords the rate constant, kb for the buffer-catalyzed reaction for each substituent. A Hammett plot of kb vs. σ is linear with ρ = +0.55, suggesting that the buffer-catalyzed reaction involves nucleophilic displacement of the phenoxy group by the buffer anion. Further analysis afforded the specific acid-catalyzed rate constants, [Formula: see text], for each substituent; this component of the reaction has a negative ρ, consistent with a mechanism involving protonation at the ether oxygen. The postulation that specific acid catalysis is a component of the reaction mechanism was confirmed by the observation of a solvent deuterium isotope effect, 2.28 > kH/kD > 1.60. Only the p-NO2 and p-CN phenyloxymethyltriazenes showed any spontaneous decomposition.

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