Correlation of Solvolysis Rates. III. 1 t-Butyl Chloride in a Wide Range of Solvent Mixtures 2

698

533

“…In treating the fluorocarbons, we have set 6 = 0 in our correlation using eq. [15]. To improve the fit, we would suggest IT* = -0.09 instead of -0.33.…”

Section: Comparison With Eq [I]mentioning

confidence: 99%

The Py scale of solvent polarities

Dong¹,

Winnik²

1984

698

533

“…Fainberg ancl \Viilstein (14) have shown that the steps indicated in ieaction [IV] need t o be coilsidered in a reaction which proceeds by a dissociatioil nzechanisin. These steps are intended to represent the sequence of events in which the tiiro ionic fragments of the reaction first become separate identities in intimate coiltact (i~lternal ion pair (14)), then ions in contact but each ion \vitIl an indepeildeilt solvation sheath, and finally separated and independent ions.…”

Section: Ici~zet Ic Dfeaszwementsmentioning

confidence: 99%

Substitution at Octahedral Centers: Ii. Effect of Salts Upon the Rate of Hydrolysis of the Halopentamminechromium(iii) Ions

Jones¹,

Harris²,

Wallace³

1961

A study of the hydrolysis of the halopentamminechromium(II1) ions in the presence of the sodium salts of weak acids reveals a rate acceleration due to specific ion-pair formation. The acceleration is due partly to a charge-transfer elfect and partly to the fact that the ion helps to maintain the octahedral configuration of the complex in the transition state. I t is concluded that the reaction occurs by dissociation, but without collapse of the structure to a five-co-ordinated intermediate.

“…A rate increase at higher NaOAc concentrations could have been anticipated as a result of a normal salt effect (18). Alternatively, if products were formed from the free, dissociation triphenylvinyl cation, a greater extent of product formation with a consequent decrease in external ion return and an increase in rate would be expected at higher salt concentrations.…”

Section: Resultsmentioning

confidence: 99%

Rearrangement studies with ¹⁴C. XLIV. Ion-pairs and dissociated ions in the solvolysis of triphenyl[2-¹⁴C]vinyl and trianisyl[2-¹⁴C]vinyl bromides in 70% acetic acid – 30% water

Lee¹,

Ko²,

Rappoport³

1980

. Lors de la solvolyse du bromure (Br-1-I4C-2) de triphenylvinyle (14C-2) dans une solution aqueuse de AcOH ? I 70%, ['addition de 30 equiv. de AcONa ou de 25 equiv. de Et4NBr n'affecte pas d'une fagon significative le degrk de distribution au hasard du marqueur entre C-2 et C-1 dans le produit de la reaction. La valeur moyenne obsewte pour le melange est de 14,7 f 0,7% dans le cas du Br-1 14C-2 sous differentes conditions. D'autre part, on a trouve que la solvolyse du bromure (Br-2-14C-2) de trianisylvinyle (14C-2) dans les m h e s conditions provoquent une distribution au hasard dont le degre diminue avec une augmentation de AcONa ajoutee. Les taux de distribution au hasard observes varient d'une moyenne de 27,7% a 5,7% respectivement dans les reactions se faisant avec ou sans addition de AcONa 10 M. Dans le cas du Br-1-I4C-2, on considere la possibilite d'une ionisation se faisant au moyen d'une paire d'ions dans lesquels la distribution au hasard, qui provient d'unglissement 1,2du phenyle, n'est pas affectke par la presence du AcO-. Dans le cas du Br-2-14C-2, une dissociation plus poussee du cation trianisylvinyle se produit e t dans I'ion dissocit la competition entre les reactions de distribution au hasard et celle de capture avec tous les nuclCophiles presents provoque une diminution du degre de distribution au hasard avec la presence du AcO-plus nucl8ophile. En utilisant les degres de distribution au hasard observees ainsi que les donntes relatives aux produits obtenus on a tvalue plusieurs rapports comprenant: ksoHlkr, kAcolkl.. ~A C O~~H~O et ~A C O~~A C O H .