2,4,6-Trimethylpyrylium trifluoromethanesulfonate (CAS NO.: 40927-60-4) could be produced through the following synthetic routes.

In a 150-ml. Erlenmeyer flask are mixed 18 ml. (19.4 g., 192 mmol.) of acetic anhydride and 3.2 ml. (2.5 g., 34 mmol.) of anhydrous t-butyl alcohol. Two to three drops of trifluoromethanesulfonic acid is added and the mixture is swirled rapidly until the initial esterification reaction is complete (temperature stops rising). Further trifluoromethanesulfonic acid (total acid: 3.0 ml., 5.0 g. (33 mmol.)) is added in 0.1–0.2-ml. portions, over 10 minutes, with swirling and pausing between each addition until the temperature begins to fall. At the end of the addition the temperature is 60–70°, and the solution is brown in color. It is allowed to stand for a further 5 minutes and then is cooled in ice. Anhydrous ether (100 ml.) is added, whereupon the pyrylium salt separates. The mixture is filtered with suction using a sintered glass funnel and the crude product is washed with a further 50 ml. of dry ether, giving 3.6–3.8 g. (40–42%) of mustard colored to pale brown plates, m.p. 116–118°.

The crude product is recrystallized from dioxane-acetic acid (7:1) or chloroform-carbon tetrachloride (2:1). The crystal form is very variable; needles, plates, or prisms may be formed, depending on the rate of formation, and the temperature. After recrystallization the 2,4,6-trimethylpyrilium trifluoromethane sulfonate melts at 119–120°.