E 2431 (OTTO) Ethyl 4-bromobutyrate, 98% Cas 2969-81-5 - used in Enzyme-linked immunosorbent assay for zilpaterol. E 2431 (OTTO) Ethyl 4-bromobutyrate, 98% Cas 2969-81-5 - used in the synthesis of isosteric thieno[2,3-b]-azepin-4-ones, having anti-tumor activity. E 2431 (OTTO) Ethyl 4-bromobutyrate, 98% Cas 2969-81-5 - used in the synthesis of poly(2,6-dimethyl-1,4-phenylene oxide)