Description Preparation Note Acetronitrile / Activator 42 100 / 7 (v/w) Other Notes Activator solution, containing 5-(3,5-bis(trifluoromethyl)phenyl)-1H-tetrazole (Activator 42) in acetonitrile, are mixed with solutions of phosphoramidites during the extension step. The activator reacts with the amidite group to form a highly reactive intermediate. The intermediate then forms an internucleotide bond with the detritylated 5′hydroxyl group of the growing oligonucleotide chain. Legal Information This product and it use is are covered under US Patent Number 7,897,758 Activator 42 is a registered trademark of Sigma-Aldrich Co. LLC