ABSTRACT

The polychlorinated biphenyls (PCB) are a class of chlorinated, aromatic compounds which have found widespread applications because of their general stability and inertness as well as their excellent dielectric properties. PCB's have been prepared industrially since 1929 and are now produced in many industrial countries. Most information by far is available on Monsanto's PCB preparations (the Aroclors) and this particular brand will serve to discuss various aspects of PCB in general. PCB's are prepared industrially by the chlorination of biphenyl with anhydrous chlorine and iron filings or ferric chloride as catalyst. The outstanding physical and chemical characteristics of PCB are their thermal stability, resistance to oxidation, acid, bases, and other chemical agents as well as their excellent dielectric properties. The most important physical properties of PCB's from an environmental point of view, are solubility and vapor pressure. The solubility of PCB's in water is low and decreases with increasing chlorine content.