Kinetics and mechanism of hydrolysis of some amine–cyanoborances in acid perchlorate media

Das, Mrinal K.; Bandyopadhyay, Soumendra Nath; Bhattacharyya, Siddhartha; Banerjee, Rupendranath

doi:10.1039/dt9910002929

Cited by 10 publications

(5 citation statements)

References 11 publications

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“…Several compounds similar to those described above as reaction intermediates are reported and investigated in the literature, as, for example, L 2 BH 2 + , (H 2 O)(L)BH 2 + , and LBH 2 X (L = tertiary amine, X = Cl, Br, I, CN). , The conclusion is that the nature of both L and X strongly influences the rate and the mechanism of hydrolysis of L 2 BH 2 n , as well as those of all the other hydroboron species LBH 3 n and L 3 BH n .…”

Section: Resultsmentioning

confidence: 90%

“…The mechanism of hydrolysis of AB should be revised by assuming the existence of two parallel reaction paths taking place at low acidities according to reaction 4 and at high acidities according to reaction 5, respectively. Taking also into account the studies reported on the kinetics and mechanism of hydrolysis of some amine−haloboranes 40 and amine−cyanoboranes, the sequence of intermediates that are formed in the AB hydrolysis in strongly acidic media could be (L could be one or more groups among H 2 O, OH - , and Cl - ). Alternatively, at lower acidities, the displacement of NH 3 group according to reaction 4 results in the reaction path already described for BH 3 in reaction 8.…”

Section: Resultsmentioning

confidence: 99%

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Role of Hydroboron Intermediates in the Mechanism of Chemical Vapor Generation in Strongly Acidic Media

2004

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Unknown and controversial aspects related to the mechanisms of hydrolysis of borane complexes and to the mechanisms of chemical vapor generation for trace element determination in strongly acidic media (0.01-10 M HCl) have been investigated and clarified. The overall hydrolysis rates of borane complexes (BH(4)(-), H(3)N-BH(3)) in the acidity range of 0.2-10 M HCl were several orders of magnitude lower than those predicted by kinetics laws and obtained in the pH range of 3.8-14. The decomposition of the borane complexes takes place stepwise and proceeds through the formation of hydroboron intermediates, L(x)()BH(4)(-)(x)()(n)() (x = 1, 2, 3), where L could be one or more species among the donor groups H(2)O, NH(3), OH(-), and Cl(-) and n is the charge of the hydroboron species (n = 0, +1, -1, depending on L). Some intermediates present surprisingly long lifetimes at elevated acidities and play a key role in determining both the overall hydrolysis rates of borane complexes and the reactivity of Hg(II), As(III), Sb(III), Bi(III), Se(IV), Te(IV), and Sn(IV) in chemical vapor generation for trace element determination. Atomic absorption experiments demonstrated that almost all trihydroboron species (LBH(3)(n)()), dihydroboron species (L(2)BH(2)(n)()), and monohydroboron species (L(3)BH(n)()) play an active role in the generation of elemental mercury and stibine. Some of these intermediates are inactive or play a marginal role in the generation of arsine, bismuthine, and hydrogen selenide. Hydrogen telluride is preferentially formed by those hydroboron species, which are stable in strongly acidic conditions, while the same species are unreactive in the generation of stannane. The collected experimental evidence is in agreement with the general reactivity of the elements in chemical vapor generation techniques and, together with other literature data, definitely rule out the hypothesis of "nascent hydrogen" as a possible mechanism of chemical vapor generation by borane complex derivatization.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Role of Hydroboron Intermediates in the Mechanism of Chemical Vapor Generation in Strongly Acidic Media

2004

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“…for S ¼ 5/2] and Ru III systems containing one unpaired electron [ B ¼ 1.73 B.M. for S ¼ 1/2][22,28], but B is slightly lower than expected for six unpaired electrons resulting from the presence of Mn II and Ru III in the same structural unit. The value of B is slightly lower than the theoretical one for a system containing six unpaired electrons, which suggests that there may be a weak interaction between Mn II and Ru III centers in the complexes.…”

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confidence: 82%

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide

Singh

Kar

Lal³

et al. 2009

Journal of Coordination Chemistry

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“…Das et al [78] reported that, during aqueous hydrolysis at pH 5.3, the evolution of H 2 was observed for about 15 min but HCN was completely lost after dissolution. In this second case, a reaction could be proposed:…”

Section: Hydrolysis Of [Bh 3 Cn] -mentioning

confidence: 99%

“…Little, sometimes controversial, information is available on the kinetics and the mechanism of hydrolysis of [BH 3 CN] -(CBH) which is known to be much more resistant to acid hydrolysis than [BH 4 ] - [61,66,78] (see Table 3). The initial step of the hydrolysis of CBH follows the same reaction pattern as that for [BH 4 [61] proposed protonation of boron to give an intermediate, BH 2 CN(H 2 ), the structure of which has been predicted to be similar to that of BH 3 (H 2 ) [79].…”

Section: Hydrolysis Of [Bh 3 Cn] -mentioning

confidence: 99%

Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

D’Ulivo

Dědina

Mester

et al. 2011

Pure and Applied Chemistry

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Aqueous-phase chemical generation of volatile hydrides (CHG) by derivatization with borane complexes is one of the most powerful and widely employed methods for determination and speciation analysis of trace and ultratrace elements (viz. Ge, Sn, Pb, As, Sb, Bi, Se, Te, Hg, Cd, and, more recently, several transition and noble metals) when coupled with atomic and mass spectrometric detection techniques. Analytical CHG is still dominated by erroneous concepts, which have been disseminated and consolidated within the analytical scientific community over the course of many years. The overall approach to CHG has thus remained completely empirical, which hinders possibilities for further development. This report is focused on the rationalization and clarification of fundamental aspects related to CHG: (i) mechanism of hydrolysis of borane complexes; (ii) mechanism of hydrogen transfer from the borane complex to the analytical substrate; (iii) mechanisms through which the different chemical reaction conditions control the CHG process; and (iv) mechanism of action of chemical additives and foreign species. Enhanced comprehension of these different mechanisms and their mutual influence can be achieved in light of the present state of knowledge. This provides the tools to explain the reactivity of a CHG system and contributes to the clarification of several controversial aspects and the elimination of erroneous concepts in CHG.

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Kinetics and mechanism of hydrolysis of some amine–cyanoborances in acid perchlorate media

Cited by 10 publications

References 11 publications

Role of Hydroboron Intermediates in the Mechanism of Chemical Vapor Generation in Strongly Acidic Media

Role of Hydroboron Intermediates in the Mechanism of Chemical Vapor Generation in Strongly Acidic Media

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide

Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

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