Tetrahedral intermediate in hydrolysis

Similar experiments have indicated the reversible formation of tetrahedral intermediates in hydrolysis of other esters, amides, anhydrides, and acid chlorides, and are the basis of the general mechanism we have shown for nucleophilic acyl substitution. 

The antiperiplanar, lone-pair hypothesis is based on the presumption that the lifetime of a tetrahedral intermediate in hydrolysis is shorter than the average time of rotation about the C-O bond that is, the barrier of conformational transition exceeds the reaction barrier. However, a simple intermediate (hydrogen orthoester) has been detected, and on this basis, the antiperiplanar, lone-pair theory was questioned.Similarly, studies on the hydrolysis of saccharide derivatives 4os indicated that the departure of... 

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