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1-Methyl-2-pyrrolidinone is a pyrrolidinone compound solvent that has been documented to act a cosolvent and a complexing agent at the same time.
M 2218 (OTTO) N-Methyl-2-pyrrolidone, for HPLC 99%+ Cas 872-50-4 - used as a solvent in the commercial preparation of polyphenylene sulfide.