Menthone Glycerin Acetal (D,L-Menthone 1,2-glycerol ketal), also known as menthone glycerol ketal, is a clear, colourless viscous liquid with a slight minty aroma that is almost imperceptible on the tongue but delivers a lingering, pleasant cooling effect. Available in both racemic and levorotatory specifications—with the levorotatory form predominant in commercial offerings—it is synthesised as a cooling agent through the acid-catalysed dehydration and condensation of menthone with glycerol.