Effect of temperature on the acidolysis of N-acyl-N,alpha,alpha-trialkyl glycine amides as related to the nature of substituents.

摘要: The C-terminal amide bond of N-acyl-N,α,α-trialkyl glycine amides is labile to acid and this has been currently assigned steric crowding within the amino residue. However, our previous work shown that in acidolysis some these compounds hindrance seems play a less important role than what one would expect. Thus, cleavage two sets such bearing different degrees was investigated at five temperatures order clarify effect structure on reactivity terms enthalpy entropy activation. exhibited an Arrhenius-type behaviour, both enthalpies entropies activation were calculated by taking advantage transition state theory. In addition, kinetic data analysed isokinetic relationships find evidence support react under same mechanism. changes reaction rate are governed activation, which related energy hindrance, respectively. general, very negative for all investigated, reflects large constrictions associated with formation state. they sensitive substrates. Copyright © 2005 European Peptide Society John Wiley & Sons, Ltd.