Alkaline copper quaternary

Alkaline copper quaternary, usually abbreviated ACQ, is a type of water-based wood preservative product containing a soluble copper(II) complex and quaternary ammonium alkyl- or aryl-substituted compounds ('quats'). Thus the product was originally called ammoniacal copper/quaternary ammonium. Alkaline copper quaternary, usually abbreviated ACQ, is a type of water-based wood preservative product containing a soluble copper(II) complex and quaternary ammonium alkyl- or aryl-substituted compounds ('quats'). Thus the product was originally called ammoniacal copper/quaternary ammonium. The copper in the preparation is in the form of a soluble complex with ammonia NH3 or an amine such as ethanolamine N(C2H5)H2). In any case, the copper content is usually expressed as a weight percentage of the amount of copper oxide CuO that would account for the copper present. As a copper carrier, ammonia has the advantage that it will penetrate difficult-to-treat Western species better than other waterborne preservatives. Otherwise ethanolamine is preferred as copper carrier. The quaternary ammonium cation in some formulations is didecyldimethylammonium (DDA) N+(CH3)2(C10H21)2. DDA is commercially produced as the carbonate, under the trade name 'Carboquat'. The carbonate is used instead of the chloride to reduce corrosion of the treatment equipment. DDA carbonate is non-volatile and highly soluble in water, with near zero octanol/water partition coefficient. Another quaternary ammonium cation used in some formulations is alkyldimethylbenzylammonium (ADBA). The formula is N+(CH2)2(C6H5)(CnH2n+1), where n varies between 8 and 18. Both the copper complex and the quats are positive cations. The counterions (the anions that balance their positive charges) are typically hydroxide HO−, chloride Cl−, carbonate CO2−3 or bicarbonate HCO−3. Formulations of ACQ differ in the 'carrier' (complexing agent for copper), either ammonia or ethanolamine; and on the quaternary ammonium cation present. Types registered in the US and Canada: