Top left: plot of the fractional abundances, relative to H₂, of cyanopolyynes as a function of envelope radius using the Rate12 model (solid lines) compared with the results from CM09 (dotted lines). Top right: plot of fractional abundances of polyynes as a function of envelope radius for the Rate12 model including anion chemistry (solid lines) and excluding anion chemistry (dashed lines). Bottom left: plot of fractional abundances of polyyne anions as a function of envelope radius. Bottom right: comparison of the fractional abundances of various cations and electrons, including anion chemistry (solid lines) and excluding anion chemistry (dashed lines). The C₆H⁻ fractional abundance for the “anions included” model is shown, for reference, with a dot-dashed line.