The Kinetics of Alkaline Hydrolysis and n-Butylaminolysis of Ethyl p-Nitrobenzoate and Ethyl p-Nitrothiolbenzoate^1a

Dynamic combinatorial chemistry at the phospholipid bilayer interface

“…A comparison of the data shows that rates of thioester exchange are comparable for DCLs containing 1a (Figure 2a and 2c) or 1b (Figure 2b and 2d) when subjected to the same conditions, whereas hydrolysis of 1b proceeds significantly faster than that of benzoic acidderived thioester 1a. This observation is consistent with reports that aliphatic thioesters are prone to hydrolysis, particularly at higher pH [51,59,60]. These plots also demonstrate that thioester exchange proceeds considerably faster with increased pH.…”

Covalent binding and hemolytic activity of complement proteins.

“…Therefore, the k2 value for the inactivation reaction of CS with the free base is 1360 M-1 min-1, an extremely high value, three orders of magnitude faster than values obtained from the n-butaminolysis of ethyl thioacetate (25) and ethyl p-nitrothiobenzoate (26). In order to account for the extreme sensitivity of C3 to methylamine, we suggest that there exist on C3, in the vicinity of the thioester, one or more catalytic groups that cause the elevated rate of reaction.…”

Mechanism of Hydrolysis and Aminolysis of Homocysteine Thiolactone

“…[9] Hence, a more complex mechanism (for example, that in Scheme 4) and rate laws with linear as well as quadratic terms in amine and hydroxide concentration become necessary. [10][11][12]15] Proton transfer can occur in an intra-as well as intermolecular fashion, hence the role of base catalysis (by a hydroxide, or a second amine molecule) observed in the aminolysis of esters, thioesters and lactones. [10][11][12][13][14][15] Second, whereas oxoesters and thioesters exhibit similar reactivities towards hydrolysis, aminolysis occurs more readily with thioesters than with oxoesters.…”

“…Several instances report that the aminolysis of esters or thioesters is base catalysed, [10][11][12][13][14] in particular, by the attacking amine itself (which requires the introduction of quadratic terms in the rate law) or by hydroxide ions. In the present case, no catalysis by hydroxide ions seems to occur, since the apparent rates measured are pH independent above the pK a value of the attacking amine.…”