Vinyl Pyrrolidone, N-Vinylpyrrolidone, Vinyl Pyrrolidinone, VP, NVP, 88-12-0

Vinyl Pyrrolidone, N-Vinylpyrrolidone, Vinyl Pyrrolidinone, VP, NVP, 88-12-0

1-VINYL-2-PYRROLIDONE (VP) 

1. PHYSICAL AND CHEMICAL PROPERTIES

Chemical Formula : C₆H₉NO
Molar Mass : 111.14 g/mol
CAS Number : 88-12-0
EC No : 201-800-4
HS Code : 2933.79.00
Appearance : Colourless to pale yellow clear liquid
Odour : Characteristic, amine-like
Melting Point : 13–14 °C
Boiling Point : ~92–95 °C (at 11 mmHg)
~214 °C (at atmospheric pressure, with decomposition)
Density : ~1.04 g/cm³ (20–25 °C)
Solubility : Completely miscible with water, alcohols, ethers, ketones and most organic solvents.
pH (100 g/L in water) : 9–10 (basic character due to the presence of NaOH or amine inhibitor)
Flash Point : ~95 °C (closed cup)
Auto-ignition Temperature : ~240 °C
Explosion Limits : 1.4 – 10 % (v/v) in air
Vapour Pressure : ~0.12 hPa (at 20 °C)
Refractive Index : n₂₀/D 1.512
Dynamic Viscosity : ~2.5 mPa·s (25 °C)
Stabilisation : Typically stabilised with 0.01–0.1 % of NaOH, potassium hydroxide or N,N’-di-2-naphthyl-p-phenylenediamine. Uninhibited monomer is prone to polymerisation.
WGK (German Water Hazard Class) : 1 (low hazard to waters)

2. SAFETY AND HAZARD CLASSIFICATION (GHS/CLP)

Hazard Pictograms : GHS02 (Flame), GHS07 (Exclamation mark)
Signal Word : Warning
Hazard Statements (H) :
H226 : Flammable liquid and vapour.
H302 : Harmful if swallowed.
H312 : Harmful in contact with skin.
H315 : Causes skin irritation.
H319 : Causes serious eye irritation.
H332 : Harmful if inhaled.
H335 : May cause respiratory irritation.
Precautionary Statements (P) :
P210 : Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
P261 : Avoid breathing vapour.
P280 : Wear protective gloves/protective clothing/eye protection/face protection.
P305+P351+P338 : IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Storage : Store in a cool (<25 °C), dry and well-ventilated place, away from direct sunlight and heat sources, in tightly closed containers. The effectiveness of the inhibitor should be checked periodically to prevent polymerisation. Avoid prolonged contact with air.

3. APPLICATION AREAS

• Polymer Production : Primary monomer for the synthesis of polyvinylpyrrolidone (PVP) and various copolymers (e.g., VP/VA copolymers). PVP is widely used as a binder in pharmaceuticals, cosmetics, food and industrial applications.

• Coatings and Inks : Used as a reactive diluent, binder and crosslinking agent in UV-curable systems. Provides fast curing and good adhesion.

• Pharmaceutical Excipients : Starting material for PVP-based nanoparticle carrier systems, tablet binders, film coatings and solubility-enhancing polymers.

• Research and Development : Employed as a monomer in genotoxicity studies, the synthesis of novel photoinitiator systems and controlled polymerisation techniques (RAFT, ATRP).

• Personal Care : VP/acrylate copolymers serve as film formers in hair styling products.

4. PRODUCTION METHOD

Method : Base-catalysed vinylation of 2-pyrrolidone with acetylene (Reppe vinylation).
Reaction : 2-Pyrrolidone + Acetylene → 1-Vinyl-2-pyrrolidone
Catalyst : Potassium hydroxide (or sodium hydroxide/potassium alkoxide) supported liquid-phase reaction.
Process : Conducted at elevated temperature (120–160 °C) and high pressure, followed by purification by distillation and addition of inhibitor.
Purity : Commercial product is typically supplied at ≥99 % purity in stabilised form.

5. REACTIONS AND CHEMICAL BEHAVIOUR

• Radical Polymerisation : Forms PVP via homopolymerisation in the presence of thermal or UV initiators. Readily copolymerises with monomers such as acrylates, vinyl acetate and styrene.

• Vinyl Group Reactions : Undergoes addition reactions, hydroformylation, hydroboration and halogenation across the double bond.

• Ring Reactions : The lactam ring can be opened by controlled hydrolysis, though it is generally preserved during polymerisation.

• N-Alkylation and Derivatisation : The nitrogen atom is amenable to further functionalisation.

6. ALTERNATIVES AND SIMILAR MONOMERS

• N-Vinylcaprolactam (VCap) : A vinyl monomer with a lower toxicity profile and more hydrophobic character, used in the synthesis of temperature-responsive polymers.

• Acrylamide : A widely used alternative in water-based polymer systems; however, it carries a neurotoxic monomer risk.

• Vinyl acetate (VAc) : A lower-cost vinyl ester monomer offering different solubility and film-forming properties.

• 2-Pyrrolidone : The precursor in VP production; also used as a solvent and chemical intermediate.

7. OTHER NAMES AND TRADE DESIGNATIONS

Chemical Names : 1-Vinyl-2-pyrrolidone, N-Vinylpyrrolidone, 1-Vinyl-2-pyrrolidinone, N-Vinyl-2-pyrrolidone
Abbreviations : VP, NVP, V-Py
Common Names : PVP monomer, Vinyl pyrrolidone, UV-curable reactive diluent

8. TYPICAL USAGE RATES (Formulation Ranges)

• PVP homopolymer production : Up to 100 % monomer (in solution or bulk polymerisation, depending on conditions).

• UV-curable coatings and inks : 5–30 % by weight of the total formulation as a reactive diluent.

• Pharmaceutical carrier systems (nanoparticle synthesis) : 1–10 % level in the polymer structure or as a grafting monomer.

• Cosmetic polymers : VP content typically in the range of 20–60 % of the copolymer composition.

1-VINYL-2-PYRROLIDONE (NVP): SECTORAL APPLICATIONS, FORMULATIONS & ALTERNATIVES

1. INDUSTRIAL APPLICATIONS

The primary use of NVP is as a monomer for producing polyvinylpyrrolidone (PVP) and its various copolymers. These polymers are critical across a wide range of industries.

• Pharmaceutical and Biomedical: PVP is an indispensable excipient. It functions as a tablet binder, enhances the solubility and bioavailability of active pharmaceutical ingredients (APIs), and is used in the manufacture of controlled-release hydrogels and nanoparticles. It also serves as a plasma volume expander (blood plasma substitute).

• Cosmetics and Personal Care: Polymers derived from NVP, especially VP/VA copolymers, are key film formers and fixatives in hair sprays, styling gels, shampoos, and conditioners. In skincare, they act as moisturizers and emulsion stabilizers.

• Industrial Coatings, Inks, and Adhesives: NVP is widely used as a monofunctional reactive diluent in UV-curable systems. When added to a formulation, it reduces viscosity for easier application, improves adhesion to various substrates, enhances film hardness, and accelerates cure speed. It also helps reduce volatile organic compound (VOC) emissions.

• Textiles and Others: In the textile industry, it is used to impart water and stain-repellent finishes to fabrics. It also finds applications as a dispersing agent in paper manufacturing and as a clarifying agent (fining agent) in beer and wine production.

2. USAGE RATES AND SAMPLE FORMULATIONS

The concentration of NVP and its derived polymers varies significantly depending on the target application and desired performance characteristics.

UV-Curable Coatings and Inks
NVP acts as a reactive diluent that becomes part of the final polymer network, reducing the need for volatile solvents.

• Oligomer (Binder): Urethane acrylate or epoxy acrylate (40–60% by weight)

• Reactive Diluent (Monomer): 1-Vinyl-2-pyrrolidone (5–30% by weight) combined with other acrylate monomers like TPGDA or HDDA.

• Photoinitiator: (1–5% by weight)

• Additives: Wetting agents, defoamers, etc. (up to 1% by weight)

In this system, increasing the NVP content lowers the overall formulation viscosity and often increases the surface cure speed, but the exact ratio must be optimized to balance adhesion, flexibility, and final film properties.

Cosmetic and Hair Care Products (VP/VA Copolymers)
VP/VA copolymers are the most common polymers in hair styling. The ratio of VP to VA dictates the film's stiffness, flexibility, and moisture resistance.

Sample Hair Spray Formulation Concept:
A typical commercial hair spray uses a 70:30 VP/VA copolymer delivered as a 50% solution in ethanol. The final solid content of the polymer in the product usually ranges from 0.5% to 7% by weight.

Pharmaceutical Applications
In oral solid dosage forms (tablets), PVP is used as a dry or solution binder, typically at concentrations of 0.5% to 5% by weight.

3. SYNONYMS

1-Vinyl-2-pyrrolidone is known by several chemical and trade names. Recognizing these synonyms is useful for procurement and reviewing technical literature.

• Primary Chemical Names:

  • 1-Vinyl-2-pyrrolidone

  • N-Vinyl-2-pyrrolidone

  • 1-Vinyl-2-pyrrolidinone

• Common Abbreviations:

  • NVP (most commonly used)

  • VP

  • V-Py

• Systematic and Other Names:

  • 1-Ethenyl-2-pyrrolidinone (IUPAC name)

  • N-Vinylbutyrolactam

  • Vinylpyrrolidone

The resulting homopolymer, Polyvinylpyrrolidone, is also known as Povidone and Polyvidone.

4. ALTERNATIVES AND COMPARATIVE ANALYSIS

While NVP is a versatile monomer, alternative chemistries exist that offer different performance, safety, or cost profiles.

• N-Vinylcaprolactam (NVCL or VCap): This is the closest structural alternative to NVP. NVP has a 5-membered lactam ring, whereas NVCL features a 7-membered ring. This structural difference makes NVCL more hydrophobic and crucially gives its polymer (PNVCL) a sharp lower critical solution temperature (LCST) in water (~32–38 °C). This thermoresponsive behavior makes PNVCL unique for biomedical applications like controlled drug release. Both monomers have a similar toxicological profile, being classified as harmful and causing serious eye damage.

• Acrylamide: A lower-cost monomer widely used in water-based polymer systems for soil conditioning and water treatment. The primary drawback of acrylamide is its potent neurotoxicity as a monomer, which poses significant health risks and severely limits its use in pharmaceutical or cosmetic applications where NVP is preferred.

• Vinyl Acetate (VAc): More economical than NVP and rarely used alone. Instead, it is frequently copolymerized with NVP to create VP/VA copolymers. This combination leverages the superior film hardness, adhesion, and water compatibility of NVP while introducing the flexibility of VAc and reducing the overall material cost.

Summary Comparison of Alternatives

5. FREQUENTLY ASKED QUESTIONS (FAQ)

• Why is NVP always supplied with an inhibitor?
  NVP monomer is highly reactive and prone to spontaneous, exothermic radical polymerization when exposed to heat, light, or initiator impurities. Inhibitors like sodium hydroxide (NaOH) or N,N'-di-sec-butyl-p-phenylenediamine are added at low concentrations (typically 0.01–0.1%) to quench free radicals, ensuring safe storage and handling before its intended use.

• What is a typical method for producing PVP?
  Industrially, PVP is most commonly produced via free-radical polymerization in an aqueous solution. A typical initiation system involves hydrogen peroxide (H₂O₂) as the initiator and ammonia (NH₃) as an activator. On a laboratory scale, azo-initiators like AIBN (azobisisobutyronitrile) are also frequently used in solution polymerization.

• How can I optimize the amount of NVP in my UV-curable formulation?
  Optimization is a balancing act. Start by formulating within the typical 5–30% range. A higher NVP concentration will decrease viscosity and often improve cure speed and adhesion, but it may make the final film more brittle and increase shrinkage. The optimal level is found by testing the trade-off between application properties (viscosity) and final film performance (adhesion, flexibility, hardness) required for your specific substrate and use case.

• What is the practical difference between VP/VA 70:30 and 30:70 copolymers in a hair spray?
  The difference is in the stiff-to-flexible nature of the film. A 70:30 copolymer (high VP) creates a hard, high-hold film that is excellent at preventing curl droop in high humidity but may feel stiff or flake if overused. A 30:70 copolymer (high VAc) creates a soft, flexible hold that feels more natural. It is less resistant to humidity and will not provide the same level of mechanical hold, making it suitable for flexible-hold or conditioning products.