Potentiometric Titration of 2,4-Dinitrophenylhydrazones of Ketones with Sodium Nitrite.

Baldinus, Joseph G.; Rothberg, Irvin

doi:10.1021/ac60188a015

Cited by 3 publications

(1 citation statement)

References 9 publications

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“…The 2,4-dinitrophenyihydrazones of ketones may be titrated potentiometrically with sodium nitrite. Titrations are carried out in tetrahydrofuran containing sulfuric and hydrochloric acids (7).…”

Section: Methods and Proceduresmentioning

confidence: 99%

Titrations in Nonaqueous Solvents

Streuli¹

1964

Anal. Chem.

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L acid-base phenomena in nonaqueous solvents has been marked in the past two years by a significant increase in papers dealing with the more fundamental aspects of the problem. There have been publications on acidbase behavior in acetonitrile (28,78,80,110), ethvlenediamine (186), teri-butvl alcohol (97), and dimethylsulfoxide (81), together with a number of articles on conductivity in a variety of solvents.These investigations demonstrate again that a number of factors must be considered when discussing acid-base behavior in any solvent.Following the established order ( 147) the present review covers papers published between October 1961 and October 1963. The above-mentioned topics together with papers dealing with new or improved titrants, electrodes, solvents, indicators, redox titrations, Lewis acics, and methods and procedures are included. Not all papers published in tris time interval are reviewed, of course, some through

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Section: Methods and Proceduresmentioning

confidence: 99%

Titrations in Nonaqueous Solvents

Streuli¹

1964

Anal. Chem.

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Determination of Carbonyl Compounds by Sodium Nitrite Titration of Excess 2,4-Dinitrophenylhydrazine in the Presence of Hydrazone

Kurlansik¹,

Salim²

1966

Journal of Pharmaceutical Sciences

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Entropy and Enthalpy Contributions to Solvent Effects on Phosphate Monoester Solvolysis. The Importance of Entropy Effects in the Dissociative Transition State

Hoff

Hengge

1998

J. Org. Chem.

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The solvolysis reactions of a series of aryl phosphates in tert-butyl alcohol and in tert-amyl alcohol have been examined. The dianion of p-nitrophenyl phosphate reacts 7500-and 8750-fold faster in these solvents, respectively, than the corresponding aqueous reactions. The monoanion reacts 14-and 16-fold slower respectively in tert-butyl alcohol and in tert-amyl alcohol. Analysis of the activation parameters shows that the rate enhancement for the dianion is due solely to entropic factors, while the slower reaction of the monoanion is due to increased enthalpy of activation. The significantly more positive entropy of activation for the solvolysis of p-nitrophenyl phosphate dianion in tert-butyl alcohol supports the original proposal that racemization at phosphorus in this reaction is caused by a switch to a D N + A N mechanism, rather than subsequently proposed mechanisms which avoid the formation of metaphosphate. Rate enhancements of similar magnitudes are seen for the dianion reactions of all of the aryl phosphates examined; the slope of a plot of the rate constants for solvolysis versus the aqueous pK a of the leaving phenols has a slope of -1.1, within experimental error of the value for the aqueous reaction. However, in the reactions in tert-amyl alcohol, para-substituted and meta-substituted aryl phosphates fall on separate but parallel lines with para-substituted compounds reacting faster than meta-substituted reactants with leaving groups of similar pK a . The pK a values for a series of para-and meta-substituted phenols in tertbutyl alcohol and in tert-amyl alcohol were determined and were found to have a linear relationship with the aqueous pK a values, with no distinction between para and meta substitution. Thus the different Brønsted behavior of para-and meta-substituted aryl phosphates in these solvents is not due to differential solvent-induced perturbations of the pK a values of the leaving groups. The mechanistic implications of these results and their relevance to enzymatic phosphoryl transfer are discussed.

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Potentiometric Titration of 2,4-Dinitrophenylhydrazones of Ketones with Sodium Nitrite.

Cited by 3 publications

References 9 publications

Titrations in Nonaqueous Solvents

Titrations in Nonaqueous Solvents

Determination of Carbonyl Compounds by Sodium Nitrite Titration of Excess 2,4-Dinitrophenylhydrazine in the Presence of Hydrazone

Entropy and Enthalpy Contributions to Solvent Effects on Phosphate Monoester Solvolysis. The Importance of Entropy Effects in the Dissociative Transition State

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