synthesis of indigo To a capless 20mL vial (Note: the cap shouldNOT be placed on the vial at any time during this experiment) add: a 1-cm stir bar, 5ml acetone, 5mL distilled H o. and 0.50g o gin stirring. drop wise over a period of 5 minutes. Next, let the mixture for minutes to allow it to return to room temperature. Using a Hirsch funnel, vacuum filter the contents the vial as quickly as possible. may work better form fine crystals that may clog the filter like if it is poured through too for slow pourers. Also, do not allow the filtrate to become or the system will clog.) the vial with 10mL H20 and add this to before the product becomes Before this liquid passes though the filter completely, wash the filtrate with 5mlu cold 95% ethanol. Remove the product from the filter, allo so do air dry, and then weigh the dry product. Indigo's melting point is above the range of laboratory thermometers not attempt to find the melting point of the product.