N-Diazo coupling of 4-chlorobenzenediazonium chloride with α-amino acids

Remeš, Marek; Diviš, J.; Zvěřina, V.; Matrka, M.

doi:10.1135/cccc19762566

Cited by 7 publications

(2 citation statements)

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“…At pH 2 and [AA] $ 4 · 10 À3 m, k obs values approach that for the thermal decomposition of 4NBD, and thus the observed acid dependence excludes a hypothetical reaction at the O-atoms (O-coupling reaction) of the carboxylic acid, which is partially ionized at pH 2, a reaction which otherwise is usually considered unlikely [15]. Therefore, the reaction between 4NBD and glycine and serine mainly takes place through the nonprotonated amino group of the amino acids, in keeping with previous results from similar reactions [30] [31].…”

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confidence: 74%

“…Most of the kinetic studies have been carried out in alkaline solution, and contradictory reports appeared. For instance, Howard and Wild [29] reported that the products of the reaction are pentaza-1,4-dienes (R 1 ÀN¼NÀNR 2 ÀN¼NÀR 3 ) , but later investigations by Remes et al [30] and Mejstrik et al [31] claimed that at pH ca. 8 -10, only triazenes are formed.…”

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confidence: 98%

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Effects of Micellar Aggregates on the Kinetics and Mechanism of the Reaction between 4‐Nitrobenzenediazonium Ions and Some Amino Acids

Fernández-Alonso

Bravo‐Díaz

2007

Helvetica Chimica Acta

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We have explored the kinetics and mechanism of the reaction between 4-nitrobenzenediazonium ions (4NBD), and the hydrophilic amino acids (AA) glycine and serine in the presence and absence of sodium dodecyl sulfate (SDS) micellar aggregates by means of UV/VIS spectroscopy. The observed rate constants k obs were obtained by monitoring the disappearance of 4NBD with time at a suitable wavelength under pseudo-first-order conditions. In aqueous acid (buffer-controlled) solution, in the absence of SDS, the dependence of k obs on [AA] was obtained from the linear relationship found between the experimental rate constant and [AA]. At a fixed amino acid concentration, k obs values show an inverse dependence on acidity in the range of pH 5 -6, suggesting that the reaction takes place through the nonprotonated amino group of the amino acid. All kinetic evidence is consistent with an irreversible bimolecular reaction with k ¼ 2390 AE 16 and 376 AE 7 m À1 s À1 for glycine and serine, respectively. Addition of SDS inhibits the reaction because of the micellar-induced separation of reactants originated by the electrical barrier imposed by the SDS micelles; k obs values are depressed by factors of 10 (glycine) and 6 (serine) on going from [SDS] ¼ 0 up to [SDS] ¼ 0.05m. The hypothesis of a micellar-induced separation of the reactants was confirmed by 1 H-NMR spectroscopy, which was employed to investigate the location of 4NBD in the micellar aggregate: the results showed that the aromatic ring of the arenediazonium ion is predominantly located in the vicinity of the C(b) atom of the surfactant chain, and hence the reactive ÀN þ 2 group is located in the Stern layer of the micellar aggregate. The kinetic results can be quantitatively interpreted in terms of the pseudophase kinetic model, allowing estimations of the association constant of 4NBD to the SDS micelles.

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supporting

confidence: 74%

mentioning

confidence: 98%

Effects of Micellar Aggregates on the Kinetics and Mechanism of the Reaction between 4‐Nitrobenzenediazonium Ions and Some Amino Acids

Fernández-Alonso

Bravo‐Díaz

2007

Helvetica Chimica Acta

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Diazohydroxides, Diazoethers and Related Species

Bravo‐Díaz

2010

Patai's Chemistry of Functional Groups

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Arenediazonium, ArN 2 + , ions may function as Lewis acids reacting with nucleophiles (Lewis bases, Nu − or NuH followed by loss of a proton) to give covalently bonded adducts, ArN 2 ‐Nu, at the β‐nitrogen of the arenediazonium ion, which is the electrophilic reactive center. Typical examples of covalently bonded adducts are the azo dyes (C‐coupling) but atoms other than C may be involved and the present chapter will mainly focus on the chemistry of O‐coupling adducts of the type ArN=N‐Nu, e.g., where Nu = OH − (formation and decomposition of diazohydroxides and diazoates), Nu = RO − , ArO − , ROH and cyclodextrins (formation and decomposition of diazoethers), with special emphasis on the kinetics and mechanism of the reactions involved. We will also cover, to a lower extent, those reactions with other nucleophiles leading to S‐, N‐ and P‐adducts. O‐coupling reactions are complicated by two major features. First, the formed adducts may display geometrical isomerism, leading to the E ‐( syn ) and Z ‐( anti ) forms, which show different stability and can be interconverted to each other by acid catalyzed processes. Second, some of the O‐adducts formed may be, in turn, components of a Lewis acid‐base equilibrium, for example between ArN 2 + and OH − ions, and hence may undergo further reactions.

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