CHEMISTRY OF POLYCHLORINATED BIPHENYLS (PCBs)

Running head : THE CHEMISTRY OF POLYCHLORINATED BIPHENYLS (PCBs

The Chemistry of Polychlorinated Biphenyls (PCBs

Name

University

Course

Date

The Chemistry of Polychlorinated Biphenyls (PCBs

Introduction

Polychlorinated biphenyls also known as PCBs belong to a group of 209 synthetic organic chemicals composed of between 1 and 10 atoms of chlorine attached to biphenyl rings (1 . These individual chlorinated biphenyl rings , congeners , were mainly manufactured as mixtures comprising of 60-90 congeners . The PCBs have a general formula of C12H10-xClx (1 . PCBs are sparingly soluble in water but highly soluble

br in oils , fats and organic solvents . They are stable compounds and not easily degradable although some thermal , biochemical and chemical factors can degrade PCBs through spontaneous (metabolically ) or intentional (incineration ) processes (1 . Degradation of PCBs by heat requires enormous application of heat energy and metabolic degradation proceeds slowly as compared to other compounds

The once highly controversial PCBs were produced as complex isomers with varying numbers of chlorine atoms . They were manufactured and sold with a 4 digit number attached to their trade names where the first two numbers referred to the carbon atoms attached to the biphenyl rings and the other two numbers referred to the chlorine percentage by mass in the PCBs mixture (1 . For instance , Aroclor 1260 contained 12 atoms of carbon attached to the biphenyl rings and had 60 percent chlorine in its total mass (1

The commercial applications of PCBs were mainly made possible by their physical and chemical stability such as thermal and chemical resistance which attracted...