A practical guide to N-methyl-2-pyrrolidone, what it is used for, where its US regulatory position stands, and how it compares with DMSO, from a US-based distributor.
NMP (N-methyl-2-pyrrolidone, CAS 872-50-4) is a high-boiling polar aprotic solvent that dissolves resins, polymers, and cured coatings that most solvents will not touch. It is used in petrochemical extraction, lithium-ion battery electrode manufacture, electronics cleaning, and paint stripping. US occupational use is the subject of a pending EPA rulemaking under TSCA.
| Property | Value |
|---|---|
| Chemical name | N-Methyl-2-pyrrolidone |
| Synonyms | NMP, 1-methyl-2-pyrrolidinone, N-methylpyrrolidone, M-Pyrol |
| CAS number | 872-50-4 |
| Molecular formula | C5H9NO |
| Molecular weight | 99.13 g/mol |
| Appearance | Clear, colorless to pale yellow liquid |
| Boiling point | Approx. 202 °C |
| Melting point | Approx. −24 °C |
| Water solubility | Miscible in all proportions |
| Grades supplied | Technical, industrial |
| Packaging | Drums, totes |
| Documentation | COA & SDS provided on request |
Values above are published physical constants for the pure substance, not a Stratus specification. Certificates of analysis are provided with each shipment; tell us your purity and water content requirement and we will confirm what is available.
NMP is a five-membered lactam, the N-methylated form of 2-pyrrolidone. It is a clear, faintly amine-smelling liquid that is completely miscible with water and with most organic solvents.
Its usefulness comes from an unusual combination: high polarity without an acidic proton, a high boiling point, low volatility, and a high flash point. That combination lets it dissolve polymers, resins, and aromatics that non-polar solvents cannot, while staying in the pot at elevated process temperatures instead of flashing off. Few solvents cover that range, which is why NMP became entrenched in processes that are now difficult to reformulate away from it.
NMP is used in refineries for extractive distillation, separating aromatics from aliphatics and recovering butadiene from C4 streams. Its selectivity for unsaturated and aromatic compounds, plus its thermal stability under repeated regeneration cycles, makes it well suited to continuous extraction service.
NMP is the solvent for the PVDF binder in cathode electrode slurries. The slurry is coated onto foil and the NMP is driven off and recovered. This is the application where NMP demand has grown fastest and where substitution is hardest, because the solvent choice is bound to the binder chemistry rather than being an incidental formulation decision.
Semiconductor and display fabrication use NMP to strip photoresist and clean substrates, where its solvency and low ionic contamination matter more than its cost.
NMP entered industrial and consumer paint strippers largely as a replacement for methylene chloride. It works on cured epoxies, polyurethanes, and multi-layer coatings, though more slowly than the solvent it replaced. This is the use category most directly affected by EPA's proposed rule.
As a carrier solvent, NMP allows higher active-ingredient loading in emulsifiable concentrates and soluble liquids, which reduces packaged volume per acre treated.
This is the part most buyers need before they specify NMP, so it is worth stating plainly.
EPA completed a TSCA risk evaluation for NMP in December 2020 and issued a revised risk determination in December 2022 finding that NMP, taken as a whole chemical substance, presents an unreasonable risk of injury to human health. The identified risks are reproductive and developmental, and they are driven primarily by direct skin contact rather than by inhalation.
In June 2024 EPA published a proposed risk management rule under TSCA section 6. As proposed, it would prohibit manufacture, processing, distribution, and use of NMP for several occupational conditions of use; require worker protection through an NMP workplace chemical protection program, or prescriptive controls including concentration limits, for most remaining occupational uses; set a concentration limit on consumer adhesives and sealants; and add recordkeeping, labeling, and downstream notification requirements.
That rule has not been finalized as of this writing. EPA's regulatory agenda has targeted a final rule during 2026. NMP is separately restricted in the European Union under REACH, where placing it on the market is conditioned on derived no-effect levels being addressed in the safety data sheet and exposure scenarios. Anyone building NMP into a new process should check the current status of the federal rule and their own state requirements rather than relying on a summary, including this one.
| NMP | DMSO | |
|---|---|---|
| Solvency for cured coatings | Very high | Very high, comparable in most stripping duty |
| Boiling point | Approx. 202 °C | Approx. 189 °C |
| Freezing point | Approx. −24 °C, liquid in cold storage | Approx. 19 °C, freezes at room temperature, needs heated storage |
| Water miscibility | Miscible | Miscible |
| US regulatory position | Unreasonable risk determination; TSCA rulemaking pending | No TSCA section 6 restriction; widely used as the substitution target |
| Primary exposure concern | Dermal absorption, reproductive and developmental effects | Rapid skin penetration, carries dissolved substances through skin |
| Typical role | Incumbent in refining, batteries, electronics | Common replacement in stripping and agrochemical carriers |
How to choose: for paint stripping, industrial cleaning, and agrochemical carrier duty, DMSO does most of what NMP does with a substantially better regulatory and toxicological position, and it is the substitution most formulators land on. Where DMSO loses is in processes tuned around NMP's specific solvency and its behavior with PVDF, and in cold environments, since DMSO freezes near room temperature and needs heated storage and lines. NMP also remains the incumbent in refinery extraction, where decades of process data sit behind it. The honest summary is that DMSO is the better default for new formulation work, and NMP is difficult to displace where an existing process was designed around it.
We supply both. If you are working through a substitution, see our DMSO guide.
Store NMP in closed containers in a cool, dry, well-ventilated area, away from strong oxidizers. It is hygroscopic, so drums left open will pick up water, which matters in electronics and battery use where water content is specified.
The control that matters most is dermal, and it is the one most often gotten wrong. NMP is absorbed readily through skin and permeates many common glove materials, so gloves must be selected on measured breakthrough time for NMP rather than on a general chemical-resistance chart. Nitrile disposables are not adequate for immersion or sustained contact. Consult the Safety Data Sheet and your EHS advisor for the specific controls that apply to your operation.
NMP is combustible with a high flash point, so it does not carry the fire risk of a low-boiling solvent, but it will burn. And because it is fully water-miscible, it will not phase-separate out of an aqueous waste stream, which needs to be accounted for in disposal planning rather than discovered later.
NMP (N-methyl-2-pyrrolidone) is a high-boiling polar aprotic solvent used to extract aromatics and butadiene in petrochemical refining, as the electrode slurry solvent in lithium-ion battery manufacture, as a photoresist stripper in electronics, as a carrier solvent in agrochemical formulations, and in industrial paint and coating removers. Stratus Chemical supplies technical and industrial grade NMP in the United States.
The CAS number for NMP is 872-50-4. Its molecular formula is C5H9NO and its molecular weight is 99.13 g/mol. It is also known as N-methyl-2-pyrrolidone, 1-methyl-2-pyrrolidinone, and M-Pyrol.
No. As of August 2026 NMP is not banned in the United States. EPA determined in a revised December 2022 risk determination that NMP presents an unreasonable risk to human health, and in June 2024 proposed a risk management rule under TSCA section 6 that would prohibit certain occupational uses, require a workplace chemical protection program for most others, and set concentration limits on consumer products. That rule has not been finalized. Buyers using NMP should track the rulemaking and verify current requirements with their EHS advisor.
EPA's risk evaluation identified reproductive and developmental effects, including post-implantation fetal loss from short-term exposure and reduced fertility from long-term exposure, primarily through direct skin contact rather than inhalation. NMP is readily absorbed through the skin, which is why the proposed controls focus on dermal exposure.
The right replacement depends on why the NMP is there. DMSO is the common substitute in paint stripping and agrochemical carrier applications, with a comparable polar aprotic solvency profile and a much better toxicological position. Dibasic esters, benzyl alcohol, and gamma-valerolactone appear in coating removal. In battery electrode manufacture, replacement is harder because NMP is tied to PVDF binder chemistry, and water-based systems require reformulating the electrode. Stratus Chemical supplies both NMP and DMSO and can quote either.
Yes. NMP is completely miscible with water in all proportions, and also with most common organic solvents. That miscibility is why it works as an extraction solvent and why aqueous rinse steps are practical after cleaning, but it also means NMP will not separate out of an aqueous waste stream, which affects disposal.
Store NMP in closed containers in a cool, dry, well-ventilated area away from strong oxidizers. It is hygroscopic and will pick up water from humid air, which matters where dryness is specified, such as in electronics and battery applications. The critical control is dermal: NMP passes through many common glove materials, so glove selection must be based on breakthrough data for NMP specifically rather than on general chemical-resistance ratings.
Stratus Chemical supplies technical and industrial grade NMP in drums and totes, with a certificate of analysis provided for each shipment. Tell us your grade, purity requirement, and volume and we will confirm pricing and availability within one business day.
Considering alternatives? See DMSO or acetone. Browse all products or request a quote.
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