(c) Diethyl carbonate is a liquid reagent that is easy to handle. In contrast, phosgene is a highly toxic and corrosive gas. Show how you might use diethyl carbonate instead of phosgene to make Lexan®.

Verified step by step guidance

1. Identify the functional groups in diethyl carbonate and phosgene. Diethyl carbonate has two ethoxy groups and a carbonyl group, while phosgene has two chlorine atoms and a carbonyl group.
2. Understand the role of phosgene in the synthesis of Lexan®. Phosgene is typically used to introduce carbonate linkages in the polymer chain by reacting with bisphenol A.
3. Consider how diethyl carbonate can be used to introduce similar carbonate linkages. Diethyl carbonate can react with bisphenol A to form the carbonate linkage, releasing ethanol as a byproduct.
4. Propose a reaction mechanism where diethyl carbonate reacts with bisphenol A. The hydroxyl groups of bisphenol A can attack the carbonyl carbon of diethyl carbonate, leading to the formation of the carbonate linkage and ethanol.
5. Evaluate the conditions needed for the reaction. Consider the use of a catalyst or base to facilitate the reaction, and ensure that the reaction conditions are mild enough to prevent decomposition of diethyl carbonate.

Key Concepts

Diethyl Carbonate

Diethyl carbonate (DEC) is an organic compound used as a solvent and reagent in organic synthesis. It is a versatile carbonyl source that can participate in various reactions, including transesterification and carbonylation. Its liquid state and lower toxicity compared to phosgene make it a safer alternative for chemical processes.

Phosgene

Phosgene is a colorless gas with a musty odor, primarily used in the production of isocyanates and polycarbonate plastics. It is highly toxic and poses significant health risks, making its handling and storage challenging. Understanding its reactivity and the risks associated with its use is crucial when considering safer alternatives like diethyl carbonate.

Polycarbonate Synthesis

Polycarbonate synthesis typically involves the reaction of bisphenol A with phosgene to produce Lexan®, a durable thermoplastic. The process can be adapted to utilize diethyl carbonate as a carbonyl source, allowing for the formation of polycarbonate without the hazards associated with phosgene. This shift emphasizes the importance of exploring safer synthetic routes in organic chemistry.