Vinyl Acetate (108-05-4) Physical and Chemical Properties

Chemical Profile

Vinyl Acetate

A volatile acetate ester used industrially as the monomer and intermediate for polyvinyl acetate/polyvinyl alcohol production and for formulating adhesives, coatings and specialty polymers.

CAS Number	108-05-4
Family	Carboxylic acid esters
Typical Form	Colorless liquid (monomer)
Common Grades	BP, EP, JP, USP

Primarily supplied and procured as a monomer and intermediate for adhesives, paints, coatings and polymer manufacture; formulation and QA/QC teams commonly handle inhibited grades to control undesired polymerization and to facilitate safe storage and processing.

Vinyl acetate is a small aliphatic vinyl ester (acetate ester) with the molecular formula C4H6O2. Structurally it comprises a vinyl functionality (\(–CH=CH_2\)) directly bonded to an acetate oxygen (structure often written CH3COOCH=CH2), giving an electron-rich olefinic site adjacent to an ester linkage. The combination of a low-molecular-weight ester group and an unconjugated vinyl double bond produces a compound that is volatile, moderately lipophilic, and chemically activated toward radical polymerization and ester hydrolysis.

Electronically, the carbonyl in the acetate fragment withdraws electron density from the adjacent oxygen while the vinyl double bond remains susceptible to radical and electrophilic addition; this underlies the compound’s readiness to undergo free-radical polymerization and its sensitivity to peroxide formation and autoxidation. Acid- or base-catalyzed hydrolysis yields acetic acid and vinyl alcohol, the latter rapidly tautomerizing to acetaldehyde; these hydrolysis pathways are kinetically significant under alkaline conditions and underlie aspects of environmental and biological transformation. With negligible hydrogen-bond donating capacity (no H-bond donors) but two H-bond acceptors (the carbonyl oxygen and the ester oxygen), the molecule shows limited aqueous solubility while remaining miscible with many organic solvents.

In practical use vinyl acetate is an industrial monomer produced and consumed in very large volumes: it is the principal monomer for polyvinyl acetate and a precursor to polyvinyl alcohol and numerous copolymers used in adhesives, paints/coatings, textiles, paper, and some food-contact polymer formulations. Commercial handling emphasizes stabilization (inhibitors) to prevent uncontrolled polymerization and engineering controls to manage the compound’s flammability and inhalation hazards.

Common commercial grades reported for this substance include: BP, EP, JP, USP.

Basic Physical Properties

Density

• Reported liquid density: \(0.932\) at \(68\,^\circ\mathrm{F}\) (EPA, 1998). Relative density (water = 1): \(0.93\). Equivalent weight-per-gallon reported as \(7.79\ \mathrm{lb}\) per gallon in some specifications.
• Interpretive note: with a density below unity vinyl acetate will float on water; combined with its vapor density (heavier than air) this contributes to ground-level vapor accumulation hazards.

Melting Point

• Reported values: \(-93.2\,^\circ\mathrm{C}\); also listed as \(-100\,^\circ\mathrm{C}\) and \(-136\,^\circ\mathrm{F}\).
• Interpretive note: the very low melting point indicates the substance is a liquid under normal environmental and process temperatures.

Boiling Point

• Reported values: \(72.50\,^\circ\mathrm{C}\) at \(760.00\,\mathrm{mmHg}\) (also given as \(72.7\)–\(72.8\,^\circ\mathrm{C}\)); equivalent reported as \(162\)–\(163\,^\circ\mathrm{F}\).
• Interpretive note: relatively low normal-boiling point correlates with substantial vapor pressure at ambient temperatures and facile volatilization.

Vapor Pressure

• Reported values: \(83\) to \(140\ \mathrm{mmHg}\) at \(68\) to \(86\,^\circ\mathrm{F}\); \(90.2\ \mathrm{mmHg}\) at \(20\,^\circ\mathrm{C}\) (extrapolated); vapor pressure also listed as \(115.0\ \mathrm{mmHg}\) and \(11.7\ \mathrm{kPa}\) at \(20\,^\circ\mathrm{C}\).
• Interpretive note: high vapor pressure at ambient temperatures explains the compound’s volatility and the importance of vapor-control measures in storage and processing.

Flash Point

• Reported values: \(18\,^\circ\mathrm{F}\) (EPA, 1998) and \(-8\,^\circ\mathrm{C}\) (closed cup). An open-cup flash point of \(0.5\)–\(0.9\,^\circ\mathrm{C}\) is also reported in one entry.
• Interpretive note: very low flash point indicates the material is readily ignitable at ambient temperatures and requires stringent ignition-source control.

Chemical Properties

Solubility and Phase Behavior

• Water solubility: commonly reported as approximately \(2\%\) (2.0–2.4 wt% in water at \(20\,^\circ\mathrm{C}\)); other reports list solubility as \(20\ \mathrm{mg/mL}\) at \(20\,^\circ\mathrm{C}\) or "poor" (2 g/100 mL). At \(20\,^\circ\mathrm{C}\) a saturated aqueous solution contains about \(2.0\)–\(2.4\) wt% vinyl acetate; the mutual solubility of water in vinyl acetate is about \(0.9\)–\(1.0\) wt% at the same temperature and increases with temperature.
• Miscibility in organic solvents: soluble in many organic solvents (examples reported: ethyl ether, ethanol, benzene, acetone, chloroform, etc.); listed as “soluble in organic liquids.”
• Vapor/phase behaviour: vapor density \( \approx 3.0 \) (air = 1) — vapors are heavier than air and can collect in low-lying spaces; combined with low flash point, vapor accumulation creates an explosion/flashback hazard.
• Hydrolysis: aqueous hydrolysis is kinetically relevant; an aqueous hydrolysis half‑life of approximately \(7.3\) days at \(25\,^\circ\mathrm{C}\) and pH 7 is reported, with faster rates at higher pH. Hydrolysis yields acetic acid and vinyl alcohol (which rapidly tautomerizes to acetaldehyde).

Reactivity and Stability

• Polymerization: vinyl acetate is susceptible to radical polymerization; it will polymerize on exposure to heat, light, peroxides, azo initiators, redox systems, and other radical sources. Hazardous (exothermic and potentially violent) polymerization has been reported when inhibitors are depleted or absent.
• Initiators and incompatibilities: polymerization can be initiated by organic and inorganic peroxides, azo compounds, redox systems (including organometallic components), light, and high-energy radiation. Vinyl acetate reacts dangerously with strong oxidizers, strong acids, peroxides, ozone (forming potentially explosive ozonides), and certain amines/alkylating agents; contact with silica gel or alumina vapors may be vigorous.
• Autoignition and decomposition: autoignition temperatures reported near \(402\,^\circ\mathrm{C}\) (\(756\,^\circ\mathrm{F}\)); decomposition burns giving acrid, irritating combustion products.
• Flammability/explosive limits: lower flammable limit \(2.6\%\) by volume; upper flammable limit \(13.4\%\) by volume. Vapors can form explosive mixtures with air and may travel to remote ignition sources.

Thermodynamic Data

Standard Enthalpies and Heat Capacity

• Available energetic data: reported heat of combustion values are listed as \(-9754\ \mathrm{BTU/lb} = -5419\ \mathrm{cal/g} = -226.9X10+5\ \mathrm{J/kg}\). Heat (enthalpy) of vaporization reported as \(163\ \mathrm{BTU/lb} = 90.6\ \mathrm{cal/g} = 3.79X10+5\ \mathrm{J/kg}\). Heat of polymerization reported as \(-439\ \mathrm{BTU/lb} = -244\ \mathrm{cal/g} = -10.2X10+5\ \mathrm{J/kg}\).
• Heat capacity: No experimentally established value for this property is available in the current data context.

Molecular Parameters

Molecular Weight and Formula

• Molecular formula: C4H6O2
• Molecular weight: \(86.09\ \mathrm{g}\,\mathrm{mol}^{-1}\)
• Exact/monoisotopic mass: 86.036779430

Additional structural identifiers (plain text): - SMILES: CC(=O)OC=C - InChI: InChI=1S/C4H6O2/c1-3-6-4(2)5/h3H,1H2,2H3 - InChIKey: XTXRWKRVRITETP-UHFFFAOYSA-N

LogP and Polarity

• Computed XLogP3 / log Kow: reported values \(0.7\) and \(0.73\).
• Topological polar surface area (TPSA): \(26.3\).
• H‑bonding: H‑bond donor count \(0\); H‑bond acceptor count \(2\).
• Interpretive note: log P near \(0.7\) indicates modest lipophilicity; combined with low TPSA and no H‑bond donors, vinyl acetate partitions appreciably into organic phases yet retains measurable water solubility.

Structural Features

• Functional groups: vinyl (ethenyl) double bond and acetate ester (acetoxy) group. The vinyl substituent provides a polymerizable olefinic site; the ester carbonyl oxygen contributes H‑bond acceptor character and susceptibility to hydrolysis and ester‑cleavage reactions.
• Chemical behavior: the vinyl group is prone to radical addition polymerization, chain‑transfer processes, and autoxidation; the ester linkage is hydrolyzable under acid or base catalysis and is a substrate for biological carboxylesterases that rapidly yield acetaldehyde and acetate in vivo.

Identifiers and Synonyms

Registry Numbers and Codes

• CAS Number: 108-05-4
• EC Number(s) (as reported): 203-545-4 (additional EC numbers appear in source lists)
• UN/NA Number (shipping identifier): UN1301 (vinyl acetate, stabilized)
• Other identifiers: ChEBI CHEBI:46916; UNII L9MK238N77
• Structural identifiers: SMILES CC(=O)OC=C; InChIKey XTXRWKRVRITETP-UHFFFAOYSA-N; InChI InChI=1S/C4H6O2/c1-3-6-4(2)5/h3H,1H2,2H3

Synonyms and Structural Names

• Common synonyms reported include: vinyl acetate; ethenyl acetate; acetic acid ethenyl ester; acetoxyethylene; acetic acid vinyl ester; vinyl acetate monomer; vinyl ethanoate; VAC; VAc; CH3CO2CH=CH2.
• IUPAC name (computed descriptor): ethenyl acetate

Industrial and Commercial Applications

Representative Uses and Industry Sectors

• Primary use: as the monomeric precursor for polyvinyl acetate (PVAc) and, after saponification/hydrolysis, polyvinyl alcohol (PVOH). Poly(vinyl acetate) emulsions and copolymers are major components of adhesives, paint emulsions, textile and paper treatments, binders, and construction products.
• Additional applications: copolymerization with vinyl chloride, ethylene, and acrylonitrile to produce specialty resins; use as a modifier in coatings and food‑contact films; use as intermediate in manufacture of numerous polymer resins and emulsions; use reported in chewable gum and tablet coating formulations (as derivatives/copolymers rather than monomer form in finished products).
• Industry sectors: petrochemical/monomer production, polymer and resin manufacturing, adhesives and coatings, construction products, food contact polymer manufacturing.

Role in Synthesis or Formulations

• Chemical role: monomer for homopolymerization and copolymerization; chain‑transfer agent in some polymerizations; intermediate in synthesis of PVAc‑based emulsions and PVOH.
• Formulation practice: small concentrations of polymerization inhibitors (aromatic hydroxyl compounds such as hydroquinone and alkylated phenolics, or diphenylamine) are routinely added to bulk vinyl acetate during storage and shipment to prevent uncontrolled polymerization. Inhibitor levels and choice depend on expected storage lifetime and downstream processing (e.g., hydroquinone at a few ppm for near‑term use; diphenylamine at higher ppm for long‑term storage).

Safety and Handling Overview

Acute and Occupational Toxicity

• Exposure hazards: vinyl acetate is a respiratory and eye irritant and can cause skin irritation; inhalation at sufficient concentrations can produce upper respiratory irritation, cough, hoarseness, and central nervous system effects (dizziness, narcotic effects at high concentrations). Repeated or prolonged inhalation exposure primarily affects the respiratory system.
• Toxicity data (examples reported): oral LD50 (rat) approximately \(2.92\ \mathrm{g}\,\mathrm{kg}^{-1}\); inhalation LC50 (rat, 4 h) approximately \(3680\ \mathrm{ppm}\). AEGL values reported for various exposure durations (ppm): AEGL-1 (10 min–8 h): \(6.7\); AEGL-2 and AEGL-3 listed at higher concentrations (e.g., AEGL-3 10 min: 230 ppm). Occupational exposure limits: TLV‑TWA \(10\ \mathrm{ppm}\), TLV‑STEL \(15\ \mathrm{ppm}\); NIOSH recommends a ceiling \(4\ \mathrm{ppm}\) (15‑minute) in some guidance; some regulatory frameworks list vinyl acetate as a suspected or possible carcinogen.
• Carcinogenicity/genotoxicity: vinyl acetate is metabolized to acetaldehyde, a genotoxic species in many assays; carcinogenicity assessments classify vinyl acetate variably, with international evaluation listing it among agents “possibly carcinogenic to humans” (Group 2B). Occupational medical surveillance and exposure minimization are recommended where inhalation exposures may occur.

Storage and Handling Considerations

• Fire and explosion control: keep away from heat, sparks, open flames, and other ignition sources; use explosion‑proof electrical equipment, grounding/bonding during transfer, and vapor‑tight systems where feasible. Maintain good ventilation and avoid accumulation of vapors in low areas.
• Polymerization control: store stabilized material (inhibitor present) and maintain inhibitor levels appropriate for storage duration; avoid contact with peroxides, azo initiators, strong oxidizers, and other radical initiators; protect from light and elevated temperatures.
• Storage recommendations: store in cool, well‑ventilated, fireproof areas in suitable metal (steel or stainless steel) containers; many operations recommend storage temperatures below \(37.8\,^\circ\mathrm{C}\) (\(100\,^\circ\mathrm{F}\)) and provision for inerting or nitrogen blanketing during bulk processing if operational conditions warrant.
• Personal protective equipment and emergency: use appropriate respiratory protection when engineering controls cannot maintain occupational exposure limits; wear chemical‑resistant gloves and eye protection to prevent skin/eye contact; provide eyewash and emergency showers. For spills and releases, eliminate ignition sources, ventilate, dike and absorb with noncombustible material, and use non‑sparking tools; do not discharge into drains or sewer systems.
• Regulatory/transport notes: the material is classed as a flammable liquid for transport; containers and shipments are often stabilized and labeled to reflect polymerization hazard and flammability. For detailed hazard, transport and regulatory information, users should refer to the product‑specific Safety Data Sheet (SDS) and local legislation.