An Alternative Solvent-Free Synthesis of Nopinone under Ball-Milling Conditions: Investigation of Reaction Parameters

A new method for the oxidative cleavage of 13 pinene (1) yielding nopinone (2) with potassium permanganate as oxidant under solvent-free conditions was established The reaction was performed in a conventional ball mill with use of a grinding auxiliary The auxiliary has the ability to sorb liquid reactants such as 1 on its surface to make liquid(s) accessible for mechanical impact Different reaction parameters and technical variables were assessed concerning their influence on yield and selectivity of 2 Different chemical parameters such as oxidants grinding auxiliaries and quantities were investigated Also tuning parameters including milling time, rotation frequency, and number of milling balls were explored