<b>Boron Hydrides. III. Hydrolysis of Sodium Borohydride in Aqueous Solution</b>

Davis, Robert Earl; Bromels, Edward.; Kibby, Charles L.

doi:10.1021/ja00865a001

Cited by 136 publications

(87 citation statements)

References 2 publications

(2 reference statements)

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“…The most obvious feature is that they are all inverse. This feature is not surprising since hydrolysis of sodium borohydride (27), hydrolysis of pyridine alkylboranes (28), and the methanolysis of lithium borohydride (29) all have inverse isotope effects. In the reduction of ketones by borohydride, it has been shown (30,46) that the rate determining step is transfer of the first hydrogen (Fig.…”

Section: The Terms Steric Approach Control Andmentioning

confidence: 97%

Deuterium Isotope Effects in the Reduction of Cyclohexanones. The Concepts of Steric Approach Control and Product Development Control

Wigfield¹,

Phelps²

1972

Can. J. Chem.

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Definitions for the terms steric approach control and product deuelopment control in relation to the degree of bonding in the transition state are put forward. Kinetic deuterium isotope effects in the reduction of a graded series of ketones by NaBH, and NaBD, have been measured. These effects are inverse, and show no systematic dependence on the degree of steric hindrance of the ketone. This evidence appears to invalidate the steric approach control-product development control explanation of the axial to equatorial product ratios (1). The primary isotope effect is very small, which is consistent with an early transition state in these reductions, as demanded by other explanations of product ratios, but since several other factors causing small isotope effects may be applicable, the evidence does not constitute proof of an early transition state.The main conclusions of this work have already been published in preliminary form (2).Les notions de "steric approach control" et 'kroduct deuelopment control" en relation avec le degri. de liaison dans I'ttat de transition, sont precisees. Les effets isotopiques du deuterium sur la cinbtique de reduction d'une serie de cetones par NaBH, et NaBD,, ont Ct C mesurts. Ces effets sont inverses et ne montrent aucune dependance systematique avec le degrt d'empschement sttrique de la cCtone. Cette mise en evidence montre que I'explication des rapports du produit axial et equatorial par le "steric approach control" et "product development control", n'est pas valable (1). L'effet isotopique primaire, trts faible, est compatible avec un debut d'6tat de transition dans ces rbductions. Ce rbsultat, deji mentionnt dans d'autres etudes, ne constitue pas une preuve puisque de nombreux autres facteurs peuvent Etre la cause de ces faibles effets isotopiques. Les conclusions principales de ce travail ont deja Ct C publikes dans une note preliminaire (2).

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Section: The Terms Steric Approach Control Andmentioning

confidence: 97%

Deuterium Isotope Effects in the Reduction of Cyclohexanones. The Concepts of Steric Approach Control and Product Development Control

Wigfield¹,

Phelps²

1972

Can. J. Chem.

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“…Acidic and alkaline conditions were used to slow down the hydrolysis of HAuCl 4 and NaBH 4 , respectively. 18,19 Typically, 20 mL of Au colloid was prepared in a 50 mL beaker by adding 200 μL of NaBH 4 /NaOH solution to 19.60 mL of ethanol under magnetic stirring at 600 rpm. After 30 s, 200 μL of HAuCl 4 /HCl was added and the stirring was continued for 10 s. A grey, turbid suspension was immediately formed.…”

Section: Preparation Of the Au Colloidsmentioning

confidence: 99%

Preparation of Electrically Conductive Au Thin Films by Colloid Sedimentation

Petek

Bukovec

Škofic

2015

ACSi

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Dedicated to the memory of Prof. Dr. Jurij V. Bren~i~. AbstractA novel and facile wet-chemical method for the preparation of Au thin films is presented. The Au thin films were deposited on glass substrates by the gravitational sedimentation of Au colloids. The colloids were formed by chemical reduction in ethanol using HAuCl 4 and NaBH 4 with no added surfactants. Without stabilizing agents the colloids quickly aggregated, settled to the bottom and formed a thin film. The sedimentation of the colloids was monitored using UV-vis spectroscopy. Thin films with Au loads ranging between 0.25 and 4.0 g m -2 were prepared and characterized by means of UV-vis spectroscopy, electrical resistance measurements, optical microscopy, scanning electron microscopy, and cyclic voltammetry. The results showed that nanostructured Au films with a very high specific surface area were formed. The films were electrically conductive and partially transparent to visible light.

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“…The degree of uncertainty in estimating k' could, in some cases, be relatively high. This uncertainty is due both to the contributions of the single experi- [69][70][71][72]. The only exceptions are the studies by Jolly and coworkers [60,64].…”

Section: Acid-catalyzed Hydrolysis Of Borane Complexesmentioning

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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Boron Hydrides. III. Hydrolysis of Sodium Borohydride in Aqueous Solution

Cited by 136 publications

References 2 publications

Deuterium Isotope Effects in the Reduction of Cyclohexanones. The Concepts of Steric Approach Control and Product Development Control

Deuterium Isotope Effects in the Reduction of Cyclohexanones. The Concepts of Steric Approach Control and Product Development Control

Preparation of Electrically Conductive Au Thin Films by Colloid Sedimentation

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

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