The kinetics of the breakdown of hemiorthoesters generated from dialkoxyalkyl acetates or ketene acetals have been investigated. The following compounds were studied: dimethyl hemiorthoformate (1b), diethyl hemiorthoformate (2b), 2-hydroxy-1, 3-dioxolane (3b), 2- hydroxy-4, 4, 5, 5-tetramethyl-1, 3-dioxolane,(4b), 2-hydroxy-2-methyl-1, 3-dioxolane (5b), and 2-hydroxy-2, 4, 4, 5, 5-pentamethyl-1, 3-dioxolane (6b). The whole series was studied ...