Polybrominated biphenyl

Polybrominated biphenyls (PBB ) are a class of compounds, in which a plurality of hydrogen atoms are replaced by bromine in a bicyclic system. They are characterized by high chemical stability, bio- degradable and hardly accumulate in the fatty tissue.

Production

PBB are prepared by bromination of biphenyl by means of aluminum chloride ( AlCl3 ) as a catalyst.

Properties

PBB having a biphenyl backbone ( via a single bond of two linked benzene rings ) to which one or more hydrogen are replaced by bromine atoms. The empirical formula is therefore C12H10 - xBx. There are 209 different congeners, of which only a few commercial products (eg, bromadiolone ) exist:

Use

Your application, see PBB as flame retardants, and as plasticizers in plastics. They serve as substitutes for polychlorinated biphenyls ( PCBs).

Toxicology

PBB are suspected to be toxic and carcinogenic, and hepatotoxic. In addition, toxic properties are suspected of having consequences, such as memory and muscle weakness, and immune deficiencies.

Restrictions on use

Since 1 July 2006, it is according to the Electrical and Electronic Equipment ( WEEE March 16, 2005 ) and EU Directive 2002/95/EC ( RoHS) forbidden to market of new electrical and electronic equipment containing more than 0, 1 percent by weight of PBB per homogeneous material.