Aryl acetates, aminolysis

Detailed mechanistic studies have been carried out on aminolysis of substituted aryl acetates and aryl carbonates. Aryl esters are considerably more reactive than alkyl esters because the phenoxide ions are better leaving groups than alkoxide ions. The tetrahedral intermediate formed in aminolysis can exist in several forms which differ in extent and site of protonation ... 

Aminolysis of phenyl dithioacetates, pyridinolysis of ( -ethyl dithiocarbonates, reaction of pyrrohdine with O-ethyl 5-aryl dithiocarbonates, aminolysis of chlorothionformates," pyridinolysis of alkyl aryl thioncarbonates, reaction of anionic nucleophiles with nitrophenyl benzoate and its sullur analogues, hydrolysis of methyl benzoate and phenyl acetate containing SMe, SOMe and SOaMe substituents, solvolysis of phenyl chlorothioformate, synthesis of new thiadiazoles, examination of a neighboming sulfonium group in ester hydrolysis,hydrolysis of V-type nerve agents, and the reactions of peroxymonosulfate ion with phosphorus(V) esters have all been looked at previously in this review. 

Thiophenyl acetates (366 R = Me) and propionates (366 R = Et) react with electrogenerated polysulflde ions S3 in DMF to yield thiocarboxylate ions, thiolate ions, and phenyl tetrasulfanide (367), the last deriving from the reaction of thiolate ions with sulfur (Scheme 48). Smdies of the aminolysis by a set of substimted anilines of Y-aryl dithio-2-thiophenates (368 X = S) and dithio-2-furoates (368 X = O) in acetonitrile have shown that the rate-determining step in these reactions is the departure of the thiophenolate ion from the zwitterionic tetrahedral intermediate T= = (Scheme 49). Experiments with deuteriated anilines yielded k i/IcQ values of 1.7-1.9,... 

The reaction of p-nitrophenyl acetate with 1,3-diaminopropane in chlorobenzene is intramolecularly catalysed [72]. The reaction of n-butylamine with p-nitrophenyl acetate in chlorobenzene is second order (kj) in amine and no reaction which is first order in amine was detected. In contrast, the reaction with 1,3-diaminopropane has both terms of first and of second-order in amine, and the rate constant for the reaction which is first-order in amine is at least 300 times greater than that for the undetected reaction of n-butylamine, while the rate constant for the reaction which is second-order in amine is about 14 times greater than the analogous reaction of n-butylamine [72]. Since breakdown of the tetrahedral intermediate is rate-limiting in the aminolysis of aryl esters in aprotic solvents [32], the intramolecular catalysis presumably functions in this step, possibly as symbolized by 46. 

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