The reaction order and apparent activation energy of esterification reaction of Fmoc-Tyr- (t-Bu)-OH and Wang resin were studied using the active ester method and 2,6-dichlorobenzoyl chloride method (DCB mixed anhydride method). Microwave-irradiation technique was applied to synthesize the thymopentin. Experiment results showed that the reaction order by the active ester method was 1.855 and the apparent activation energies by the active ester method and mixed anhydride method were 15.24 and 35.14 kJ/mol, respectively. Compared with the classical method, the reaction rate of forming peptide bond was increased by over 30 times, and the excessive amount of amino acid was reduced to twice from 3 times of that in the classical method.

Key words: solid-phase peptide synthesis, thymopentin, apparent activation energy, reaction order, microwave enhancement