Why does propylene carbonate dissolve salts that other organic solvents cannot?
Its dielectric constant is above 60, exceptionally high for an organic liquid and comparable to water. A high dielectric constant means the solvent screens the electrostatic attraction between ions, separating and stabilising them rather than letting them pair up and precipitate. That is what allows it to dissolve lithium salts and other ionic species.
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Why is propylene carbonate replacing NMP and DMF?
On regulatory grounds. N-methylpyrrolidone and dimethylformamide are both classified as toxic for reproduction and are restricted under REACH, which has forced reformulation across paint stripping, cleaning and extraction. Propylene carbonate offers comparable polar aprotic solvency with low acute toxicity, ready biodegradability and no CMR classification.
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What makes it suitable for battery electrolytes?
The combination of high dielectric constant, which dissolves the lithium salt, a wide liquid range from a very low freezing point to a boiling point around 242 degrees Celsius, and electrochemical stability. It is generally used in a blend with lower-viscosity co-solvents, since its own viscosity limits ion mobility if used alone.
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Is propylene carbonate stable in water?
It hydrolyses slowly in the presence of water, particularly under acid or alkaline conditions, producing propylene glycol and carbon dioxide. In most applications that is slow enough to be irrelevant, but in aqueous formulations intended for long shelf life, or at elevated pH or temperature, hydrolysis should be assessed.
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