Synthesis of ROS-cleavable thioketal linker (TK)

In a typical reaction, a mixture of anhydrous 3-mercaptopropionic acid (11.44 g, 108.02 mmol), anhydrous acetone (2.90 g, 49.10 mmol), and a catalytic amount of trifluoroacetic acid were stirred at 25 °C for 6 h. After the reaction, the flask was sealed and chilled in ice until the crystallization completed. The crystals were filtered, and washed with hexane and cold water. The product was obtained after dried in a vacuum desiccator.