A (preferably nonaqueous) method of making a dipyrromethane is described. The
comprises
the steps of: (a) providing a reaction system consisting essentially of an aldehyde
or acetal, excess pyrrole and a catalyst; (b) reacting the aldehyde or acetal with
the pyrrole in the reaction system to form the dipyrromethane therein; (c) quenching
the reaction system by adding a base thereto (preferably without simultaneously
or concurrently adding water and/or an organic solvent thereto); (d) separating
the catalyst from the reaction system; and then (e) separating the pyrrole from
the reaction system to produce the dipyrromethane as a residual