Solvent isotope effect in the acid-catalyzed isomerization of cis-stilbenes

1968 ◽  
Vol 33 (11) ◽  
pp. 4260-4261 ◽  
Author(s):  
Donald S. Noyce ◽  
Donald R. Hartter ◽  
Frank B. Miles

1974 ◽  
Vol 52 (7) ◽  
pp. 1066-1071 ◽  
Author(s):  
Edward P. Lyznicki Jr. ◽  
Kiyotaka Oyama ◽  
Thomas T. Tidwell

The hydrolysis of triethyl phosphate in water and in 35% dioxane – 65% water has been examined. Hydrolysis in neutral water proceeds with a rate constant of 8.35 × 10−6 s−1 at 101°, ΔH* = 23.4 kcal/mol, ΔS* = −20 e.u., a solvent isotope effect [Formula: see text] of 1.3, C—O bond cleavage as shown by 18O labeling, and no catalysis by 0.5 M sulfuric acid. These results are consistent with the BAL2 mechanism of hydrolysis and the same pathway is indicated for the reaction in neutral 35% dioxane –65% water. Perchloric acid catalyzes the reaction in dioxane–water with C—O bond cleavage in 0.904 M acid, ΔH* = 24.1 kcal/mol, ΔS* = −17 e.u., and the solvent isotope effect [Formula: see text] in 0.556 M acid. These results indicate that the AAL2 pathway of hydrolysis is followed under these conditions. The reactivity of triethyl phosphate is compared with that of ethyl acetate.





1993 ◽  
Vol 6 (6) ◽  
pp. 361-366 ◽  
Author(s):  
Ikchoon Lee ◽  
Won Heui Lee ◽  
Hai Whang Lee


1975 ◽  
Vol 53 (6) ◽  
pp. 869-877 ◽  
Author(s):  
B. Rossall ◽  
R. E. Robertson

The temperature dependence of the rate of hydrolysis of benzoic, phthalic, and succinic anhydrides have been determined in H2O and D2O under "neutral" conditions. Corresponding data have been obtained for methyl trifluoroacetate. While both series supposedly react by the same BAc2 mechanism, remarkable differences are made obvious by this investigation. Possible sources of such differences are proposed.



1981 ◽  
Vol 103 (10) ◽  
pp. 2897-2899 ◽  
Author(s):  
Robert A. Binstead ◽  
Bruce A. Moyer ◽  
George J. Samuels ◽  
Thomas J. Meyer


2000 ◽  
Vol 19 (9) ◽  
pp. 1682-1691 ◽  
Author(s):  
Riki Paur-Afshari ◽  
J. Lin ◽  
Richard H. Schultz


1974 ◽  
Vol 29 (4) ◽  
pp. 660-661 ◽  
Author(s):  
B. W. Epperlein ◽  
H. Krüger ◽  
. Lutz ◽  
A. Schwenk

For 67Zn NMR lines of solutions of ZnCl2, ZnBr2, and ZnI2 in H2O and D2O an anomalous solvent isotope effect is reported. In D2O solutions the lines are shifted to higher frequencies. The difference between the shieldings in H2O and D2O is e.g. σ(H2O) - σ(D2O) = (13.1 ±0.7) ppm for a concentration of 0.02 moles zinc bromide per mole solvent.



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