Thermolysis of arenediazonium salts in acidic methanol. Effects of substituents, atmospheres, and added substances on the competition between ionic and radical mechanisms

Broxton, Trevor J.; Bunnett, J. F.; Paik, Chang H.

doi:10.1021/jo00424a013

Cited by 60 publications

(55 citation statements)

References 4 publications

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“…[13] Table 5 tate with ethyl acrylate (see Table 5) shows the results we obtained on testing ethanol, acetonitrile, dichloromethane, and dioxane in coupling reactions cation reactions. Previous studies on the stabilities of diazonium salts in acidic alcoholic solutions [32,52,53] have shown that two dediazoniation reaction pathways can occur…”

Section: Quinone Diazidesmentioning

confidence: 99%

An Efficient Procedure for the Synthesis of Crystalline Aryldiazonium Trifluoroacetates – Synthetic Applications

Colas

Goeldner²

1999

Eur. J. Org. Chem.

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We have developed a very mild procedure for the synthesis of crystalline aryldiazonium trifluoroacetate salts in high yields under anhydrous conditions. Over thirty mono‐ or polyfunctional aniline derivatives have been diazotized by this method, including water‐ and acid‐sensitive substrates. The o‐ and p‐hydroxyaryldiazonium salts, derived from the corresponding anilines, could be deprotonated by treatment with K2CO3 to yield pure diazoquinones. NMR and UV/Vis spectra have been recorded for all the synthesized salts; the data are in good agreement with the rather limited published data and constitute a first extensive report of 13C‐NMR chemical shifts in diazonium salts. An excellent linear relationship emerged between Brown's substituent constants s+p and the 13Cipso chemical shifts. The diazonium salts obtained proved to be much more soluble in organic solvents than their tetrafluoroborate counterparts. They were tested in Pd‐mediated coupling reactions of various Carbon‐Carbon double bonds, and were found to give good yields within short reaction times under very mild conditions. We believe that diazonium trifluoroacetates represent a very attractive alternative to diazonium tetrafluoroborates.

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Section: Quinone Diazidesmentioning

confidence: 99%

An Efficient Procedure for the Synthesis of Crystalline Aryldiazonium Trifluoroacetates – Synthetic Applications

Colas

Goeldner²

1999

Eur. J. Org. Chem.

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“…Dediazoniation reactions, 1A, occur with a wide variety of nucleophiles and they are believed to take place through two main mechanisms [6], heterolytic (1C), and homolytic (1D). Competition between or coexistence of the pathways may occur depending on the substituents of the aromatic ring [10,11] and experimental conditions such as pH [6], solvent [5,6], or even atmosphere [11] (O 2 or N 2 ). The homolytic mechanism shows [6,12] a wider variety of pathways compared to the heterolytic one and many of them are still not completely understood [6,12].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical determination of rate constants and product yields for the spontaneous dediazoniation ofp-nitrobenzenediazonium tetrafluoroborate in acidic aqueous solution

Romero-Nieto

Bravo-Daz

Malvido-Hermelo

et al. 2000

Int. J. Chem. Kinet.

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We have examined the kinetics and mechanisms of the dediazoniation of p-nitrobenzenediazonium tetrafluoroborate in acidic aqueous solutions by employing differential pulse polarography (DPP) and differential pulse voltammetry (DPV) on a glassy carbon electrode combined with the use of a coupling reaction to quench unreacted p-nitrobenzenediazonium ion. These electrochemical techniques show an effective sensitivity and selectivity for detecting arenediazonium ions and arenedediazoniation products under the appropriate experimental conditions (pH, solvent, electrolyte), which allows simultaneous monitoring of the rates of arenediazonium ion loss and product formation and determination of product yields.

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“…Meanwhile, homolytic dediazoniations are favored by an increase in the nucleophilicity (HMPT, Pyridine). MeOH, EtOH, and DMSO have been reported as borderline solvents where both mechanisms can be observed, depending on several factors like pH [17], substituents of the aromatic ring [24,25], or even the atmosphere [25] (O 2 or N 2 ).…”

Section: Introductionmentioning

confidence: 99%

“…The present knowledge concerning dediazoniations in alcohols is based basically on the works of DeTar et al, Bunnet et al, and Broxton et al, who worked mainly under alkaline conditions [17]. However, relatively little work was done under acidic conditions [16,17,29] and OMBD does not appear to have been studied under such acidic conditions [24,25,30], so we have also examined its kinetic behavior in the presence and absence of added nucleophiles.…”

Section: Introductionmentioning

confidence: 99%

Solvolysis of o-methylbenzenediazonium tetrafluoroborate in acidic methanol-water mixtures. Further evidence for nucleophilic attack on a solvent separated aryl cation

Pazo‐Llorente

Sarabia-Rodriguez

González-Romero

et al. 1999

Int. J. Chem. Kinet.

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Rate constants for dediazoniation product formation and arenediazonium ion loss and product yields of solvolysis of o-methylbenzenediazonium tetrafluoroborate in acidic methanol-water mixtures at T ϭ 35ЊC are reported. Observed rate constants for diazonium ion loss and product formation are the same, increasing about 45% ongoing from water to methanol, and are not affected by added electrolytes like HCl, NaCl, and CuCl 2 . Only three dediazoniation products are detected, o-cresol, o-chlorotoluene, and o-anisole. All data are consistent with a rate-determining step formation of an aryl cation that reacts immediately with available nucleophiles. The selectivity of the reaction toward nucleophiles, S, which can be Correspondence to: C. Bravo-Diaz (cbravo@uvigo.es)

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Thermolysis of arenediazonium salts in acidic methanol. Effects of substituents, atmospheres, and added substances on the competition between ionic and radical mechanisms

Cited by 60 publications

References 4 publications

An Efficient Procedure for the Synthesis of Crystalline Aryldiazonium Trifluoroacetates – Synthetic Applications

An Efficient Procedure for the Synthesis of Crystalline Aryldiazonium Trifluoroacetates – Synthetic Applications

Electrochemical determination of rate constants and product yields for the spontaneous dediazoniation ofp-nitrobenzenediazonium tetrafluoroborate in acidic aqueous solution

Solvolysis of o-methylbenzenediazonium tetrafluoroborate in acidic methanol-water mixtures. Further evidence for nucleophilic attack on a solvent separated aryl cation

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