Reaction of imidazole with β-propiolactone. I, measured and calculated concentrations of β-propiolactone and products (+), hydroxypropionyl imidazole (⧫), 2-carboxyethyl imidazole (−), 1,3-bis(2-carboxyethyl) imidazole (○), and 3-hydroxypropionic acid (□), based on (II), the model with k1 = 0.000056, k2 = 0.067, k3 = 0.0098, k4 = 0.0000679, and k5 = 0.064.