Effect of pressure on the rate of hydolysis of methyl and isopropyl bromides

. J. Chem. 53,3414 (1975).The effect of pressures up to 3 kbar on the rate of the base-catalyzed hydrolysis of ethyl acetate in acetone-water mixtures has been measured. From these measurements and the enthalpy and entropy of activation at constant pressure measured by others, the internal energy and entropy of activation at constant volume have been obtained as a function of solvent composition. The constant-volume parameters of activation vary with composition in a simpler way than the constant-pressure parameters. It seems likely that theoretical discussions of the solvent effect are easier if they are based on the constant-volume parameters. At low acetone concentrations, the addition of acetone reduces the rate constant at low pressure, but increases it at 3 kbar.M. L. TONNET et E. WHALLEY. Can. J. Chem. 53,3414(1975).

Section: Experimental Methods and Resultsmentioning

confidence: 99%

Effect of Pressure on the Alkaline Hydrolysis of Ethyl Acetate in Acetone–Water Solutions. Parameters of Activation at Constant Volume

Tonnet¹,

Whalley²

1975

“…Graphical analysis of the conductance-time data by the Guggenheim method (13) The pressure dependence of the solvolysis rate of isopropyl bromide in H 2 0 has been reported (2), but in view of the surprising results obtained, the data were redetermined in these laboratories. Although, as indicated in Table 2, the rate constants at atmospheric pressure coinpare favorably with the previously reported values (2,14), the complex rate constant-pressure behavior reported previously (2) was not evident.…”

Section: Kitrelicsmentioning

confidence: 99%

Temperature Dependence of Activation Volumes of Solvolysis Reactions in Light and Heavy Water

Davis¹,

Hyne²

1973

The pressure dependence of the solvolysis rates for benzyl chloride, isopropyl bromide, and methanesulfonyl chloride in Hz0 and D20 have been measured. The temperature dependence of the activation volumes appears to be indicative of the mechanism of solvolyses and the differences in the temperature dependence of the activation volumes for the two solvents are consistent with D20 being the more structured. The more extensive data in the case of methanesulfonyl chloride deuterolysis indicates extremum behavior in AV* as a function of temperature in the 5-25 "C range.La relation entre la pression et le taux de solvolyse du chlorure de benzyle, du bromure d'isopropyle et du chlorure de mtthane sulfonyle dansl'H20et dans le Dz0 a t t t Cvalute. Larelationentre la tempkrature et les volumes d'activation semble Ztre caracttristique du mtcanisme des solvolyses. De plus, les diff6-rences dans la relation des volumes d'activation et la temptrature pour les deux solvants sont en accord avec le fait selon lequel le D20 est le mieux structurt. Les donntes les plus completes en ce qui a trait B la deuterolyse du chlorure de mtthanesulfonyle montrent un comportement extrZme du AV* en fonction de la temptrature dans I'intervalle de 5 25 "C.

“…19 has limited the testing of this identity to establishing that the parameters have indeed opposite signs in the case of the Menshutkin reaction (29) and some hydrolyses (30).…”

Section: Relationshipsmentioning

confidence: 99%

The Pseudo Thermodynamics of Solvolysis. A Detailed Study of the Pressure and Temperature Dependence of Benzyl Chloride Solvolysis in t-Butyl Alcohol – Water Mixtures

Dickson¹,

Hyne²

1971

The pseudo first order rate constants for the solvolysis of benzyl chloride in aqueous t-butyl alcohol (t-BuOH) are reported at 40.00, 50.25, and 60.50 "C at various pressures up to 4084 atm. From these data the first temperature derivatives (AH* and AS*), the first (AV*) and second pressure derivatives, aAV*/aP, and the mixed second derivative, aAVo*/aT, of the rate are evaluated. These activation parameters exhibit extremum behavior in the highly aqueous solvent region. This behavior is discussed in terms of solvent structure variation. The signs of the pressure dependence of AH* and AS* are shown to be consistent with those required by the Maxwell type relationships for classical thermodynamic systems.Les constantes de vitesse du pseudo premier ordre pour la solvolyse du chlorure de benzyle dans I'alcool tertiobutyllique (t-BuOH) sont rapportees a 40.00, 50.25, et 60.50 "C pour differentes pressions supkrieures a 4084 atm. A partir de ces donnees, les dtrivies premieres de la vitesse par rapport a la temperature (AH* et AS*), ses dkrivees premiere (AV*) et seconde par rapport a la pression, a V*/aP, et sa dkrivee seconde aAVo*/aT sont calcultes. Ces parametres d'activation montrent un comportement extrgme dans la region des solvants fortement aqueux. Ce comportement est analyse en fonction de la variation de structure du solvant. On montre que les signes de AH* et AS* dependant de la pression sont compatibles avec ceux requis par les relations du type relations de Maxwell pour des systemes thermodynamiques classiques.