... in aromatics extraction, acetylene, alkene, diene purification. 1. Formula: C5H9NO2. CAS no. : 872-50-43. Use:Widely used in aromatics extraction, acetylene ... , polyimide, polyphenylene sulphide and other engineering plastics and Kevlar fiber.4. Technology data:Molecular weight99.13Boiling point204°CFlash point95°CRefractive index1 ... liquidContent≥99%Water≤0.5% N-methyl-pyrrolidone (872-50-4)