Tetrabromophthalic Anhydride-13C6 is an intermediate in synthesizing 2,3,4,5-Tetrabromobenzoic Acid-13C6 (T291142). It is an isotope labelled analog of 2,3,4,5-Tetrabromobenzoic Acid. 2,3,4,5-Tetrabromobenzoic Acid is an in vitro metabolite of the flame retardant 2-Ethylhexyl 2,3,4,5-Tetrabromobenzoate (E918780) in human and rat tissues.