Hydrolysis of imidate esters derived from weakly basic amines. Influences of structure and pH on the partitioning of tetrahedral intermediates

1973 ◽  
Vol 95 (4) ◽  
pp. 1253-1265 ◽  
Author(s):  
Tadashi. Okuyama ◽  
Terry C. Pletcher ◽  
David J. Sahn ◽  
Gaston L. Schmir
Keyword(s):  
Hydrolysis Of ◽  
Tetrahedral Intermediates

The products of hydrolysis of cyclic orthoesters as a function of pH and the theory of stereoelectronic control

1985 ◽  
Vol 63 (9) ◽  
pp. 2485-2492 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Jean Lessard ◽  
Yves Nadeau
Keyword(s):  
Acid Hydrolysis ◽  
Hydroxy Ester ◽  
The Other ◽  
Relative Percentage ◽  
Stereoelectronic Control ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates

The acid hydrolysis of cyclic orthoesters 1, 3–6 (R = Me), and 2 (R = Me and Et) as a function of pH was studied. The bicyclic orthoester 5 yields mainly the hydroxy-ester (less than 5% lactone), and this result is essentially independent of pH. For the other orthoesters, the relative percentage of products differs for each case and varies with pH. At pH ≤ 3, the percentage of lactone is always larger than at pH > 3. These results are explained on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates.

ChemInform Abstract: THE HYDROLYSIS OF CYCLIC ORTHOESTERS. STEREOELECTRONIC CONTROL IN THE CLEAVAGE OF HEMIORTHOESTER TETRAHEDRAL INTERMEDIATES

1975 ◽  
Vol 6 (38) ◽  
pp. no-no
Author(s):  
PIERRE DESLONGCHAMPS ◽  
ROBERT CHENEVERT ◽  
ROLAND J. TAILLEFER ◽  
CLAUDE MOREAU ◽  
JOHN K. SAUNDERS
Keyword(s):  
Stereoelectronic Control ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates

scholarly journals The neutral hydrolysis of methyl acetate — Part 2. Is there a tetrahedral intermediate?

2009 ◽  
Vol 87 (4) ◽  
pp. 544-555 ◽  
Author(s):  
Zheng Shi ◽  
Yih-huang Hsieh ◽  
Noham Weinberg ◽  
Saul Wolfe
Keyword(s):  
Acetic Acid ◽  
Methyl Acetate ◽  
Acid Catalysis ◽  
Experimental Result ◽  
Acid Product ◽  
General Acid ◽  
One Step ◽  
Hydrolysis Of ◽  
Step Mechanism ◽  
Tetrahedral Intermediates

A computational strategy that reproduces the experimental rates of hydration of formaldehyde, acetaldehyde, acetone, and cyclohexanone and the rates of acetic acid and 2-hydroxypyridine-catalyzed hydration of acetone has been extended to the results of the neutral hydrolysis of methyl acetate reported in Part 1. Calculations have been performed for one-step and two-step mechanisms, with cooperative assistance from one to three additional water molecules in the presence and absence of the acetic acid product. The calculations predict that, for the neutral reaction, a one-step mechanism will be favoured if tetrahedral intermediates have a short lifetime and do not interconvert prior to breakdown (case A), and a two-step mechanism will be operative if tetrahedral intermediates are allowed to interconvert prior to breakdown (case B). The experimental results are consistent with the predictions of case A. In the presence of acetic acid, case A predicts that the acid will contribute only 1.6% to the overall rate, a negligible acceleration over the noncatalytic process, and case B predicts general acid catalysis to be an order of magnitude greater than the experimental result. It is concluded that the neutral hydrolysis of methyl acetate is mainly a cooperative one-step process, and that general acid catalysis by the acetic acid product does not occur.

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