Hydroxy- and chloro- dediazoniation of 2- and 3- methylbenzenediazonium tetrafluoroborate in aqueous solution

Pazo‐Llorente, Roman; Sarabia-Rodriguez, Maria Jose; Bravo‐Díaz, Carlos; González-Romero, Elisa

doi:10.1002/(sici)1097-4601(1999)31:1<73::aid-kin9>3.0.co;2-l

Cited by 38 publications

(43 citation statements)

References 24 publications

(21 reference statements)

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“…The effects of solvent composition on k obs were determined by changing the %TFE in the reaction mixture at a fixed acidity (−log[HCl] = 2). In the absence of TFE, k obs ∼ 8 × 10 −4 s −1 at T = 60 °C, consistent with literature values 20, 22. Values of k obs increase by a factor of almost 3 as %TFE increases from 0 to 98%.…”

Section: Resultssupporting

confidence: 90%

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Solvolyses of 4‐methylbenzenediazonium ions in trifluoroethanol/water mixtures: Effects of [TFE], acidity and temperature on the kinetics and mechanism of the reaction

Fernández-Alonso¹,

Bravo‐Díaz²

2010

J of Physical Organic Chem

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Section: Resultssupporting

confidence: 90%

“…Pre‐association stepwise mechanisms (Scheme ) in which the aryl cation has a short but finite lifetime have been used to describe product distribution in terms of ion–molecule or ion–nucleophile pairs 22, 30. Nucleophilic attack may occur on ‘free’ carbocations, contact ion–molecule pairs or contact ion–solvent pairs.…”

Section: Discussionmentioning

confidence: 99%

Solvolyses of 4‐methylbenzenediazonium ions in trifluoroethanol/water mixtures: Effects of [TFE], acidity and temperature on the kinetics and mechanism of the reaction

Fernández-Alonso¹,

Bravo‐Díaz²

2010

J of Physical Organic Chem

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“…Thus, the kinetic experiments in the absence of [CAT] confirm (i) that the main products, 3‐cresol and H 3 O + , are formed stoichiometrically and (ii) that the rate for formation of products is equal to that for 3MBD loss. These results are in line with the yields obtained by high‐performance liquid chromatography …”

Section: Resultssupporting

confidence: 89%

“…Variations of absorbance with [3MBD] are linear up to ~ 7 × 10 −4 m , Fig. (B), with ε 272 = 4700 ± 90 L mol −1 cm −1 and ε 310 = 1773 ± 19 L mol −1 cm −1 in keeping with literature values …”

Section: Methodssupporting

confidence: 87%

Kinetics and mechanism of the reaction between 3‐methylbenzenediazonium ions and catechol

Jaszczuk

Dudzik

Losada‐Barreiro

et al. 2016

J of Physical Organic Chem

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We have investigated the kinetics and mechanism of the reaction between 3‐methylbenzenediazonium, 3MBD, ions and catechol (1,2‐dihydroxybenzene, [CAT]) in aqueous buffer solution under acidic conditions by employing spectrometric UV/VIS. The variation of the observed rate constant, kobs, with the acidity at a given [CAT] follows an upward curve, with rate enhancements of up to 20‐fold on going from pH = 3.0 up to pH = 5.0, suggesting that the reaction takes place with the monoanionic form of [CAT]. At relatively high acidities, the variation of kobs with [CAT] is linear with an intercept very close to the value for the thermal decomposition of 3MBD; however, a decrease in the acidity leads to saturation kinetics profiles with non‐zero pH‐dependent intercepts, prompting us to propose a reaction mechanism comprising two consecutive equilibrium processes involving the bimolecular, reversible, formation of a highly unstable Z‐diazo ether, which undergoes isomerization to the E‐isomer through a unimolecular step. The results highlight the complexity of the reactions of arenediazonium ions with nucleophilic arenes containing two or more hydroxy groups and are valuable to exploit arenediazonium ions as chemical probes to determine antioxidant distributions. Copyright © 2016 John Wiley & Sons, Ltd.

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“…The obtained values for the activation parameters (Table II) are consistent with the proposed preassociation stepwise mechanism like the one shown in Scheme , in which the aryl cation has a short but finite lifetime, and that has been employed to describe product distribution in terms of ion–molecule or ion–nucleophile pairs 41,42. Nucleophilic attack may occur on “free” carbocations, contact ion–molecule pairs or contact ion–solvent pairs.…”

Section: Discussionsupporting

confidence: 80%

Dediazoniation of 1‐naphthalenediazonium tetrafluoroborate in aqueous acid and in micellar solutions

Bravo‐Díaz

Pastoriza-Gallego

Sánchez-Paz

et al. 2008

Int J of Chemical Kinetics

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We have measured the rates and product yields of dediazoniation of 1-naphthalenediazonium (1ND) tetrafluoroborate in the presence and absence of sodium dodecyl sulfate (SDS) micellar aggregates by employing a combination of UV-vis spectroscopy and high-performance liquid chromatography (HPLC) measurements. Kinetic data were obtained by a derivatization procedure with product yields were determined by HPLC. HPLC chromatograms show that in aqueous acid and in micellar solutions only one dediazoniation product is formed in significant quantities, 1-naphthol (NOH), and the observed rate constants (k obs ) are the same when 1ND loss is monitored spectrometrically and when NOH formation is monitored by HPLC. Activation parameters were obtained both in the presence and absence of SDS micellar aggregates. In both the systems, the enthalpies of activation are high and the entropies of activation are positive. The enthalpy of activation in the absence of SDS is very similar to that in the presence of SDS micelles, but the entropy of activation is lower by a factor of 4. As a consequence, SDS micelles speed up the thermal decomposition of 1ND and increase k obs by a factor of 1.5 when [SDS] = 0.02 M. In contrast, results obtained in the presence of complexing systems such as crown ethers and polyethers show significant stabilization of the parent arenediazonium ions. Kinetic and HPLC data are consistent with the heterolytic D N + A N mechanism that involves the rate-determining fragmentation of the arenediazonium ion into a very reactive phenyl cation that reacts competitively with available nucleophiles.

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Hydroxy- and chloro- dediazoniation of 2- and 3- methylbenzenediazonium tetrafluoroborate in aqueous solution

Cited by 38 publications

References 24 publications

Solvolyses of 4‐methylbenzenediazonium ions in trifluoroethanol/water mixtures: Effects of [TFE], acidity and temperature on the kinetics and mechanism of the reaction

Solvolyses of 4‐methylbenzenediazonium ions in trifluoroethanol/water mixtures: Effects of [TFE], acidity and temperature on the kinetics and mechanism of the reaction

Kinetics and mechanism of the reaction between 3‐methylbenzenediazonium ions and catechol

Dediazoniation of 1‐naphthalenediazonium tetrafluoroborate in aqueous acid and in micellar solutions

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