However, the intermediate tertiary alcohol is liable to dehydration in acidic conditions if the reaction temperature rises above -30°C, and since Kidston did not realize this and esterified the intermediate with propionic anhydride at room temperature, MPTP was formed as a major impurity.[2] Several days after trying this new batch of his homemade drug, Kidson developed serious PD symptoms.

Det var en feil syntese, han trodde han hadde lagd MPPP, men han lagde MPTP.