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Polycarbonates are a particular group of polymers that are moldable under heat; as such, these plastics are very widely used in modern manufacturing. The most widely used industrial polycarbonate is bisphenol A, and sometimes the general term “polycarbonate” is used synonymously with this particular chemical.
Polycarbonate is a very durable material, and can be laminated to make bullet-proof glass, though “bullet-resistant” would be more accurate. Polycarbonate is becoming more common in housewares. Other products made from polycarbonate include sunglass lenses and compact discs.
LEXAN® is the registered trademark for polycarbonate plastic manufactured by General Electric. MERLON® is the registered trademark used by the Mobay Chemical Company.
Synthesis
Polycarbonate can be synthesized from bisphenol A and phosgene. The first step in the synthesis of polycarbonate from bisphenol A is treatment of bisphenol A with sodium hydroxide. This deprotonates the hydroxyl groups of the bisphenol A molecule. The deprotonated oxygen reacts with phosgene through a back-side attack to create a tetrahedral intermediate followed by elimination of a chloride ion as a leaving group to form a chloroformate. The chloroformate is then attacked by another deprotonated bisphenol A, eliminating the remaining chloride ion and forming a dimer of bisphenol A with carbonate linkage. Repetition of this process yields polycarbonates. Polycarbonate is also widely known for it is a major material that makes up the popular Nalgene Bottles.
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