Description
TCC’s tetrabromophthalic anhydride (TBPA) is a non-hazardous, white to pale yellow crystalline powder or solid with a faintly pungent odor. TBPA is slightly soluble in Benzene and DMSO. It reacts exothermically with water. This reaction is expected to be slow, but can become vigorous if local heating accelerates it. Acids accelerate its reaction with water. TBPA is incompatible with acids, strong oxidizing agents, alcohols, amines, and bases.
TBPA is prepared by bromination of phthalic anhydride in 60% oleum (fuming sulfuric acid containing 45-65% sulfur trioxide), rendering a 95% yield. Because the halogenating agent is bromine, an excess of oleum is used to oxidize the by-product hydrogen bromide to bromine. As a result, some sulfonation of the aromatic ring occurs, which is then removed by reacting the anhydride with dilute sodium hydroxide, filtering, and acidifying with dilute hydrochloric acid. The precipitated acid, washed with hot water, is reconverted to the anhydride by heating at 150 °C for several hours.
TBPA can also be prepared by the reaction of phthalic anhydride and bromine in a mixture of concentrated sulfuric acid and 70% hydrogen peroxide in the presence of iodine, or in chlorosulfonic acid containing sulfur.
TBPA is mainly used as a flame retardant in plastics, paper, and resin.
