Correlation of Solvolysis Rates. IV.<sup>1</sup> Solvent Effects on Enthalpy and Entropy of Activation for Solvolysis of t-Butyl Chloride<sup>2</sup>

Winstein, S.; Fainberg, Arnold H.

doi:10.1021/ja01579a027

Cited by 171 publications

(90 citation statements)

References 7 publications

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“…The same was observed for the solvolysis of t-BuCl in ethanol-water mixtures [19,20,48]. Winstein and Fainberg [48] have shown that the activation free energy of t-BuCl solvolysis increases smoothly with increasing ethanol content and that the enthalpy and entropy of activation manifest clearly extremes in the region of 15 mol % ethanol. This is also the region of the maximum solvation energy of the initial reagent, t-BuCl [49].…”

Section: Ultrasound Effect On Acid-catalyzed Hydrolysis Of Aliphatic supporting

confidence: 63%

“…Moreover, the occurrence of hightemperature zones in a cavitating solution provides no adequate explanation of the observed effects in polar reactions because the absence of a sonication effect for a reaction with a positive activation energy has been documented [55] and has also been found in this work (Table 2). Besides, no correlation between ultrasound efficiency and activation energy for the solvolysis of t-BuCl in ethanol-water mixtures can be observed [20,48].…”

Section: Mode Of Ultrasound Actionmentioning

confidence: 99%

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Effect of ultrasound on ester hydrolysis in aqueous ethanol

Tuulmets

Salmar

2001

Ultrasonics Sonochemistry

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Section: Ultrasound Effect On Acid-catalyzed Hydrolysis Of Aliphatic supporting

confidence: 63%

Section: Mode Of Ultrasound Actionmentioning

confidence: 99%

Effect of ultrasound on ester hydrolysis in aqueous ethanol

Tuulmets

Salmar

2001

Ultrasonics Sonochemistry

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“…Dimethyl sulphide is liberated in the ratedetermining step as assumed in the kinetic analysis and t-butyl halide is also formed. Subsequent solvolysis or elinlination of the t-butyl halide to yield alcohol or olefin will not be rate detern~ining since the rates of such reactions under the experimental conditions used in this work are considerably greater than those of the sulphonium salt rates (10,11 salts are not greater than those observed in Fig. 4(a).…”

mentioning

confidence: 79%

SULPHONIUM SALT SOLVOLYSIS: PART II. COMMON-ION EFFECT AND THE ION-PAIR MECHANISM IN THE SOLVOLYSIS OF DIMETHYL-t-BUTYL SULPHONIUM SALTS

Hyne¹,

Abrell²

1961

Can. J. Chem.

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The kinetic effect of added common anion in the solvolysis of dimethyl-t-butyl s~~lphonium halides in ethanol-water mixtures is analyzed in terms of a mechanism involving solvolysis through a n ion-pair intermediate. The simple ion-pair role, however, does not account for the kinetic behavior a t higher added common-anion concentrations. A normal salt effect and further involvement of the ion pair in Sx2 attacl; by common anion are compared as possible explanations for the observed kinetic behavior. INTRODUCTIOXEvidence presented in the previous paper of tliis series ( I ) was interpreted as indicative of the increasing role of an ion-pair niechanism in the solvolysis of dimethyl-t-butyl sulphonium salts as the dielectric constant of the mediuni is reduced. Further experimental evidence in support of this proposed nlechanism is presented in this paper. I t is clear from equation [ I ] tliat such a mechanism should be affected by the concentration of coiiinion anion X-. Higher concentrations should favor ion-pair forniation and a higher proportion of the over-all solvolysis should proceed through the ion-pair intermediate. The over-all rate of solvolysis (kobs) of dimethyl-t-butyl sulphoiiiuin iodide and chloride has therefore been measured as a functioi~ of both added coninion anion and solvent coniposition.I11 the previous paper of tliis series it was silo\\-ii tliat if the ion-pair niecl~anism is correct, k , , > k+. Consequently, added common anion should increase the over-all rate of solvolysis (kobs) since a greater proportion of tlie solvolytic process will proceed through the faster ion-pair pathway. As the dielectric constant of the solvolytic mecli~~iii is reduced, tlie ion-pair association constant ( K , ) will increase and together witli increasing concentration of common anion these factors \\-ill result in virtually complete conversion of the sulphonium ion to the ion-pair state. The over-all rate of solvolysis slioulcl therefore increase witli added common anion and lower dielectric constant but should approach an upper limiting value as the degree of ion pairing approaches 100%. EXPERIMEXTAL METHOD .AND RESULTSAll rates were measured by tlie radiochemical flow counting technique of Hyne and Wolfgang (2). C14-labelled dimethyl-t-butyl sulphonium iodide was prepared as described previously ( 2 ) and converted to the chloride by metathesis witli freshly prepared silver chloride. Solvent mixtures were prepared by weight from doubly distilled water (lo-' mhos) and redistilled absolute ethanol. Reagent grades of lithium chloride and iodide 'Manuscript

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“…Die Frage nach der Solvens-Polarität interessiert den Chemiker seit langem 11 " 41 . Nachdem sich makroskopische physikalische Größen wie die Dielektrizitätskonstante oder der Brechungsindex für die Klärung des chemischen Reaktionsverhaltens und der damit verbundenen moleku laren Prozesse nur als begrenzt brauchbar erwiesen ha ben 11,5 " 81 , gelang mit der Entwicklung der empirischen Po laritätsskalen ein wesentlicher Fortschritt.…”

Section: Introductionunclassified

“…Nachdem sich makroskopische physikalische Größen wie die Dielektrizitätskonstante oder der Brechungsindex für die Klärung des chemischen Reaktionsverhaltens und der damit verbundenen moleku laren Prozesse nur als begrenzt brauchbar erwiesen ha ben 11,5 " 81 , gelang mit der Entwicklung der empirischen Po laritätsskalen ein wesentlicher Fortschritt. Die älteste, von Einen Eindruck der Gültigkeitsbreite von Gleichung (4) vermittelt Tabelle 2, in der ihre Anwendung bei den neun Ein solches Verhalten ist insofern bemerkenswert, als es zum einen der geläufigen Anschauung widerspricht, daß die Polarität eines Lösungsmittelgemisches in den Grenzen der Polaritäten seiner Komponenten liegt, und zum ande ren die Möglichkeit eröffnet, die Polarität von Solventien auch durch den Zusatz weniger polarer Komponenten zu erhöhen.…”

Section: Introductionunclassified

Polarität binärer Flüssigkeitsgemische

Langhals

1982

Angewandte Chemie

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Im Gegensatz zu den schon gut untersuchten Polaritätseigenschaften von reinen Flüssigkeiten ist über die Polarität von Flüssigkeitsgemischen nur wenig bekannt, obwohl die Mehrzahl der mechanistischen sowie präparativen Studien chemischer Reaktionen nicht in reinen Phasen ausgeführt wird. Mit einer breit anwendbaren Zwei‐Parameter‐Gleichung läßt sich das polare Verhalten binärer Flüssigkeitsgemische als Funktion ihrer Zusammensetzung quantitativ beschreiben. Anhand dieser Gleichung kann man jetzt die bei Solvens‐Mischungen beobachteten Abweichungen von der linearen Korrelation der Polaritätsskalen ebenso erklären wie die von Winstein bei der Solvolyse von tert‐Butylchlorid gefundenen ungewöhnlichen Aktivierungsdaten. Anwendungen der Gleichung reichen von einem Schnelltest zur Bestimmung von Wasser in organischen Lösungsmitteln über die Untersuchung von Reaktionsmechanismen bis zur Polymerchemie.

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Correlation of Solvolysis Rates. IV.¹ Solvent Effects on Enthalpy and Entropy of Activation for Solvolysis of t-Butyl Chloride²

Cited by 171 publications

References 7 publications

Effect of ultrasound on ester hydrolysis in aqueous ethanol

Effect of ultrasound on ester hydrolysis in aqueous ethanol

SULPHONIUM SALT SOLVOLYSIS: PART II. COMMON-ION EFFECT AND THE ION-PAIR MECHANISM IN THE SOLVOLYSIS OF DIMETHYL-t-BUTYL SULPHONIUM SALTS

Polarität binärer Flüssigkeitsgemische

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Correlation of Solvolysis Rates. IV.1 Solvent Effects on Enthalpy and Entropy of Activation for Solvolysis of t-Butyl Chloride2

Cited by 171 publications

References 7 publications

Effect of ultrasound on ester hydrolysis in aqueous ethanol

Effect of ultrasound on ester hydrolysis in aqueous ethanol

SULPHONIUM SALT SOLVOLYSIS: PART II. COMMON-ION EFFECT AND THE ION-PAIR MECHANISM IN THE SOLVOLYSIS OF DIMETHYL-t-BUTYL SULPHONIUM SALTS

Polarität binärer Flüssigkeitsgemische

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Correlation of Solvolysis Rates. IV.¹ Solvent Effects on Enthalpy and Entropy of Activation for Solvolysis of t-Butyl Chloride²