[‚se·trə′mōn·ē·əm ′brō‚mīd] (organic chemistry) CH3(CH2)15N(CH3)3Br Crystals with a melting point of 237-243°C; soluble in alcohol, water, and sparingly in acetone; used as a cationic detergent, antiseptic, and precipitant for nucleic acids and mucopolysaccharides.