Copper(II) acetate, also referred to as cupric acetate, is the chemical compound with the formula Cu(OAc)2 where OAc- is acetate (CH3CO2-). The hydrated derivative, which contains one molecule of water for each Cu atom, is available commercially. Anhydrous Cu(OAc)2 is a dark green crystalline solid, whereas Cu(OAc)2(H2O)2 is more bluish-green. Since ancient times, copper acetates of some form have been used as fungicides and green pigments. Today, copper acetates are used as reagents for the synthesis of various inorganic and organic compounds. Copper acetate, like all copper compounds, emits a blue-green glow in a flame. Copper(II) acetate was historically prepared in vineyards, since acetic acid is a byproduct of fermentation. Copper sheets were alternately layered with fermented grape skins and dregs left over from wine production and exposed to air. This would leave a blue substance on the outside of the sheet.