Solvent-Free Reactions of Alkynes in Ball Mills: It is Definitely More Than Mixing (Report‪)‬

The omission of solvents or the reduction of solvent intensity in chemical reactions is one of myriad possibilities to decrease the E- or Sheldon-factor for chemical syntheses and thus improve the "greenness" of a chemical process [1]. It is generally understood that reactions performed in the absence of a classical, volatile, or hazardous organic solvent(s) are classified as solvent-free or -less reactions. This categorization seems to be arbitrary, because it often includes reactions conducted either in neoteric solvents or in the reactant(s) itself [2-5].