1: p-toluenesulphonic acid / methanol / 2 h / Heating 2: 1.) propionic acid / 1.) 130 deg C, 3 h, 2.) 145 deg C, 14 h 3: 90 percent / ozone / methanol / 1 h / -30 deg C to -60 deg C View Scheme

Multi-step reaction with 2 steps 1: p-toluenesulphonic acid / methanol / 2 h / Heating2: 1.) propionic acid / 1.) 130 deg C, 3 h, 2.) 145 deg C, 14 h