D 1921 (OTTO) 4,4′-Dimethoxytrityl chloride, 98% Cas 40615-36-9 - used as a protective reagent for oligonucleotide synthesis. D 1921 (OTTO) 4,4′-Dimethoxytrityl chloride, 98% Cas 40615-36-9 - used for selective protection and deprotection procedures for thiol and hydroxy groups in nucleoside derivatives.