| HS Code | 969672 |
| Product Name | Tungsten(V) Ethoxide |
| Synonyms | Tungsten pentaethoxide; Tungsten pentethoxide; W(OEt)5 |
| Cas Registry Number | 60763-24-8 |
| Chemical Formula | C10H25O5W |
| Linear Formula | W(OCH2CH3)5 |
| Molecular Weight | 409.14 g/mol |
| Exact Mass | 409.1211 g/mol |
| Appearance | Dark brown liquid |
| Physical State | Liquid |
| Color | Brown to dark brown |
| Density | 1.54 g/mL at 25 °C |
| Boiling Point | 120 °C at 0.05 mmHg |
| Refractive Index | n20/D 1.56 |
| Solubility | Soluble in organic solvents; reacts with water |
| Moisture Sensitivity | Moisture sensitive |
| Storage Conditions | Store under inert gas |
| Reactivity With Water | Reacts with water |
As an accredited Tungsten(V) Ethoxide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Tungsten(V) Ethoxide supplied in 10 g sealed glass vials under argon, with PTFE-lined caps and moisture-resistant outer packaging. |
| Container Loading (20′ FCL) | Tungsten(V) Ethoxide loaded in sealed, palletized drums; moisture-sensitive, secured, labeled, and documented within a 20′ FCL for transport. |
| Shipping | Tungsten(V) Ethoxide is shipped as a moisture-sensitive, flammable hazardous liquid in UN-approved, sealed containers, preferably under inert gas. Use secondary containment and correct dangerous-goods labels. Store and transport cool, dry, away from water, acids, oxidizers, and ignition sources. Follow SDS, DOT/IATA/IMDG requirements for exact UN number, class, and packing group. |
| Storage | Store Tungsten(V) Ethoxide in a cool, dry, well-ventilated area, preferably under inert gas (argon or nitrogen). Keep containers tightly closed, moisture- and air-tight, away from oxidizers, acids, heat, and ignition sources. Handle under inert atmosphere or glovebox. Avoid moisture contact to prevent hydrolysis. Protect from water, alcohols, protic solvents, and direct sunlight. Use appropriate secondary containment and clear labeling. |
| Shelf Life | Shelf life: limited. Moisture-sensitive; store sealed under inert gas, cool and dry. Hydrolyzes rapidly if exposed to air or moisture. |
In semiconductor and MEMS fabrication environments where chlorine-free tungsten oxide thin films are required, tungsten(V) ethoxide [W(OC2H5)5] is handled as a moisture-sensitive liquid precursor and vaporized in either bubbler delivery or direct liquid injection systems. Electronic-grade qualification for this precursor typically specifies a metal purity of 99.999% (5N, metals basis), chloride ion below 15 ppm by ASTM D512-13, and moisture below 5 ppm by Karl Fischer titration following ASTM E203-08; any breach of ampoule sealing rapidly raises water content and initiates oligomerization.
For direct liquid injection, the precursor is diluted to a working concentration of 0.1–0.3 mol L⁻¹ in rigorously dried 1,2-dimethoxyethane or n-butyl ether, while bubbler configurations hold the stainless-steel ampoule at 70–95°C and supply 20–50 sccm of ultra-high-purity argon. Process lines are maintained 10–20°C above the ampoule setpoint to reduce condensation; dead-leg volumes greater than 50 µL in liquid-injection valves are a recurring field failure mode because stagnant precursor hydrolyzes or decomposes, producing oxide particulates that block the nozzle. The ALD process operates at substrate temperatures of 150–350°C, with alternating pulses of tungsten precursor and a co-reactant of water or ozone; typical purge durations range from 5–15 s, and saturated growth rates fall between 0.02–0.05 nm cycle⁻¹ depending on surface hydroxyl density. Film stoichiometry, crystallinity, and oxygen vacancy concentration are adjusted by varying the co-reactant pulse time and substrate temperature rather than by increasing precursor pressure, because excess precursor causes gas-phase nucleation and nonuniform thickness across 200 mm wafer batches. Terminal device types include WO3-based MEMS gas-sensing arrays, electrochromic test cells on indium tin oxide substrates, and ion-conductive thin-film structures for charge-trap and solid-state ionic devices. Production environments require ISO 14644-1:2015 Class 5 cleanroom control during ampoule changeout; point-of-use filtration through 0.05 µm PTFE is required upstream of the vaporizer to remove hydrolysis nuclei. Published data for end-use electrical performance of this precursor at sub-10-nm node logic integration is limited; qualified use remains concentrated in specialty MEMS and advanced functional oxide deposition.
Dip coating or slot-die coating of tungsten-containing sols prepared from W(OC2H5)5 is governed by the water-to-alkoxide molar ratio, because excess free water forms condensed tungsten oxide clusters that scatter visible light and reduce electrochromic modulation. The sol is formulated at 0.25–0.6 mol L⁻¹ tungsten equivalent in a solvent mixture of ethanol and 2-methoxyethanol at 80:20 volume ratio; the water-to-alkoxide ratio is held between 0.8 and 2.0, and acetylacetone is added at 3–7 mol% relative to tungsten to slow condensation and extend pot life beyond 48 h. For architectural glass lines operating at line speeds of 0.5–2.0 m min⁻¹, withdrawal speeds of 100–300 mm min⁻¹ produce gel films that dry at 120°C and are subsequently annealed in air at 350–500°C for 60 min to form nanocrystalline monoclinic WO3 layers of 150–500 nm thickness. The relevant durability specification is ISO 18543:2017, which defines accelerated ageing and electrochemical cycling requirements for electrochromic glazings; scrappage during batch production is commonly traced to edge-thickness variation greater than 12% across a 600 mm × 1000 mm glass sheet. Industrial terminal outputs include automotive electrochromic mirrors, aircraft dimmable cabin windows, and building facades that require visible-light transmittance modulation of at least 20% between bleached and colored states. Coatings with open porosity below 5% and a compact morphology are preferred for long-cycle stability; insufficient annealing leaves residual ethoxide carbon that raises coloration efficiency decay above 10% after 1000 cycles under ±2.0 V square-wave cycling.
Supported tungsten oxide catalysts prepared from ethoxide precursors demand strict exclusion of moisture because W(OC2H5)5 hydrolyzes to polytungstate clusters before the incipient wetness liquid has uniformly penetrated the γ-Al2O3 pore network. The formulation target is 5–20 mass% WO3 on gamma-alumina with a BET surface area of 180–250 m² g⁻¹ as determined by ASTM D3663; the precursor solution is adjusted to a volume equivalent to the support water pore volume, typically 0.6–0.8 cm³ g⁻¹, and introduced under a nitrogen-vented impregnator. The impregnated material is held at ambient temperature for 12 h, dried at 110°C, and calcined at 550°C for 4 h with ramp rates not exceeding 2 K min⁻¹, because exothermic alkoxide decomposition off-gassing can cause local sintered hot spots in multi-kilogram rotary calciners. The resulting tungsten surface density is typically 0.5–4 W nm⁻², below the monolayer threshold, preserving isolated and polyoxotungstate species relevant to acid catalysis. Attrition resistance is measured by ASTM D5757-11; regulatory compliance for industrial supply is governed by REACH Regulation (EC) No 1907/2006. Terminal catalyst uses include WO3/Al2O3 systems for olefin isomerization, metathesis feed pretreatments, and selective catalytic reduction of nitrogen oxides with ammonia. Published data for ethoxide-derived catalyst manufacturing at full commercial scale are limited; ammonium metatungstate remains the industrial standard where the additional cost of alkoxide-grade molecular dispersion is not justified by a demonstrated selectivity gain.
Controlled hydrolysis of tungsten(V) ethoxide in ethanol–water mixtures followed by annealing at 400°C produces WO3 nanocrystalline powders with crystallite sizes of 10–30 nm, which are formulated into screen-printable pastes for chemiresistive gas-sensor elements. The paste formulation consists of 60–75 mass% WO3 powder, 5–10 mass% lead-free glass frit, and 15–30 mass% terpineol/ethyl cellulose vehicle; platinum or palladium dopants are introduced at 2–5 mass% as chloride solutions before thermal decomposition to modify selectivity toward H2S or NO2. The paste is screen-printed onto 0.25 mm thick alumina substrates with interdigitated platinum electrodes and fired at 500°C for 30 min to remove organic binders and establish particle–electrode contact. Heater operation at 150–300°C is required for reversible conductance response; field calibration of finished detectors follows IEC 60079-29-1:2016 for flammable gas detection and EN 50271 for alarm performance of electrical equipment used in gas detection. Terminal products are fixed gas detectors for hydrogen sulfide and nitrogen dioxide, portable monitors, and indoor air quality modules integrated into HVAC demand-controlled ventilation. Published sensitivity data for specific target gases vary with electrode geometry and humidity; qualification of each paste lot at 50% relative humidity is therefore recommended before production release.
The immobilization of tungsten oxide onto TiO2 surfaces through controlled hydrolysis of W(OC2H5)5 creates a heterojunction that retards electron–hole recombination under UV and visible illumination. The formulation target is 2–5 mass% WO3 relative to TiO2, corresponding to a W/Ti molar ratio of 0.02–0.05; the tungsten ethoxide is first diluted in anhydrous ethanol at 0.1–0.2 mol L⁻¹ and added dropwise to an aqueous TiO2 slurry under high-shear dispersion at 1000–3000 rpm. The mixed slurry is coated onto cordierite or alumina honeycomb substrates by dip coating at withdrawal rates of 0.5–2.0 m min⁻¹, dried at 80–120°C, and calcined at 350–450°C for 2 h to activate the WO3/TiO2 interface. Photocatalytic activity is verified by ISO 22197-1:2016 for NO removal and ISO 10678:2010 for methylene blue degradation; coating adhesion is checked by cross-cut testing according to ISO 2409. Recurring production bottlenecks include particle agglomeration during ambient transfer of pre-hydrolyzed sol, which raises opacity and reduces active surface area; closed-vessel hydrolysis under nitrogen is used to avoid carbonate formation from atmospheric CO2 adsorption. Terminal products include self-cleaning architectural facade panels, tunnel air purification liners, and photocatalytic filters for HVAC systems. The process is unsuitable for thin transparent self-cleaning glass where nanoparticle-free morphology is required; in those cases, sputtered titania remains preferred over particulate heterojunction coatings.
When a tungsten ethoxide-derived WO3 thin film is evaluated as an anode or intercalation host, the processing route must minimize residual hydroxyl and carbon content to avoid irreversible lithium consumption during the first charge–discharge cycle. A precursor solution of 0.3–0.5 mol L⁻¹ tungsten equivalent in 2-methoxyethanol is spin-coated at 3000–5000 rpm for 30–60 s onto Pt/Ti/SiO2/Si substrates; the film is dried at 120°C and annealed at 350°C in dry air to form a 100–300 nm WO3 layer. Electrochemical testing in half-cells uses 1 mol L⁻¹ LiClO4 in propylene carbonate, with a lithium metal counter electrode and potential windows of 2.5–3.5 V versus Li/Li+. Transport regulation for cells incorporating the film is governed by UN Manual of Tests and Criteria Part III subsection 38.3 and cell safety testing by IEC 62133-2:2017; electronic assembly must respect Directive 2011/65/EU recast. Terminal applications are thin-film solid-state microbatteries for RFID tags, smart cards, and implantable or ingestible sensor nodes where substrate footprint is limited to a few square millimeters. Published data for cycle life and specific capacity of alkoxide-derived WO3 films vary widely with porosity, oxygen vacancy concentration, and electrolyte purity; comparative industrial qualification against sputtered tungsten oxide is required for any production release.
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Tungsten(V) Ethoxide, tungsten(5+) pentakis(ethoxide), is a homoleptic metal alkoxide with formula W(OC₂H₅)₅. Supplier safety data sheets commonly assign CAS registry number 19730-86-8; the calculated molecular weight is 409.15 g mol⁻¹ and the theoretical tungsten content is 44.93 wt%. The compound is supplied as a dark brown to black, moisture-sensitive viscous liquid. The W(V) center is a d¹ system; the resulting visible absorbance and paramagnetism distinguish the material from tungsten(VI) ethoxide and tungsten hexacarbonyl. Product grade is generally defined by metal purity, halide residue, and total organic impurity content rather than by a standardized model; package codes vary by supplier and container size.
Lot qualification for electronic-grade material should begin with the certificate of analysis. Trace metal contamination, particularly sodium, iron, chromium, aluminium, titanium, and molybdenum, is quantified by inductively coupled plasma mass spectrometry after acid digestion; ISO 17294-2 is the applicable multi-element method. Moisture determination by Karl Fischer titration is not always valid in the neat alkoxide because the reagent itself hydrolyzes; package moisture is therefore controlled by headspace dew point and by drying of the argon cover gas to <0.1 ppm H₂O. Chloride is measured by combustion ion chromatography and is typically specified below 100 µg g⁻¹ for electronic-grade material. Viscosity is lot-dependent because bridging ethoxide ligands alter the oligomer distribution; cone-and-plate rheometry at 25 °C is used, but published dynamic viscosity values for W(OC₂H₅)₅ are limited. Freeze-thaw cycling is not recommended because oligomer reorganization can produce sludge-like fractions.
| Benchmark | Typical Value or Derived Figure | Method or Source |
|---|---|---|
| Formula | W(OC₂H₅)₅ | Lot identity by FTIR and ICP-OES |
| CAS registry number | 19730-86-8 | Supplier safety data sheet |
| Molecular weight | 409.15 g mol⁻¹ | Calculated from IUPAC atomic weights |
| Theoretical tungsten | 44.93 wt% | Formula calculation |
| Trace metals purity | ≥99.9% metals basis | ICP-MS per ISO 17294-2 |
| Chloride | ≤100 µg g⁻¹ | Combustion ion chromatography |
| Water in cover gas | <0.1 ppm H₂O | Headspace dew point / argon purification |
| Appearance | Dark brown to black viscous liquid | Visual lot acceptance |
For production-scale receiving, the material should be sampled under inert atmosphere and evaluated for gel particles larger than 0.45 µm by pressure filtration. Batches that fail this test often contain prehydrolyzed tungsten oxide nuclei and exhibit higher viscosity with non-Newtonian shear response. Published data for this specific configuration is limited, so incoming QC tests are usually defined by the user rather than by a single standard.
When hydrolytic oxide synthesis is the intended use, the precursor is typically diluted with anhydrous 2-propanol, 2-methoxyethanol, or toluene before water addition. The hydrolysis-condensation sequence releases ethanol and forms W–O–W bridges; the water-to-alkoxide ratio R, solvent polarity, and oligomer distribution determine whether the product remains soluble or forms a gel. Because the d¹ metal center can oxidize to W(VI), dissolved oxygen must be excluded to retain the lower-valent state; otherwise the sol shifts toward yellow WO₃ stoichiometry and the reducing character of the precursor is lost. This oxygen sensitivity also means that standard air-contact mixing equipment must be replaced by sealed stirred reactors or Schlenk vessels.
The critical process variable is local water concentration at the addition point. When water is introduced as a dilute solution in anhydrous solvent, localized gelation can produce micron-sized aggregates that are difficult to disperse. A rotor-stator homogenizer operated at 8,000–12,000 min⁻¹ reduces aggregate size but increases oxygen entrainment if the vessel is not inerted. Filtration through a 0.2 µm PTFE membrane is required for optical coatings; the filter area must be sized for high gel-particle loading. In the absence of published kinetic rate constants for W(OC₂H₅)₅, formulation windows are established by parallel rheometry and UV-visible spectroscopy. Gel time can be extended by holding the sol near 4 °C and by keeping R below 1.0. Accelerated gelation above 25 °C is commonly observed, with exact gelation point shifting by batch because residual bridging ethoxide populations alter molecular weight. Production operators should therefore not transfer a solvent-formulated sol to a coating line without a viscosity rise curve recorded after mixing.
In vapor-phase processing, the compound is more restricted than tungsten(VI) ethoxide because oligomerization lowers the gas-phase monomer fraction and makes bubbler delivery irreproducible. Direct liquid injection or solution delivery to a heated vaporizer is preferred. If a conventional bubbler is employed, the vessel and downstream lines must be purged with dry argon at <0.1 ppm H₂O and predried at 120 °C for at least 12 h before charging. Published vapor-pressure curves for W(OC₂H₅)₅ are scarce; a downstream quadrupole mass spectrometer should be used to monitor partial-pressure stability before production runs. The material is not recommended for high-volume thermal CVD where precursor volatility is the main design criterion, because alternative tungsten precursors with higher vapor pressure are generally easier to control.
Tungsten(V) ethoxide differs from tungsten(VI) ethoxide primarily in metal oxidation state and ligand count. W(OC₂H₅)₆ contains six ethoxide ligands and yields stoichiometric WO₃ under typical oxidative deposition; W(OC₂H₅)₅ has one fewer donor group and can introduce oxygen-deficient WO₃−x or tungsten bronze character when the process oxygen partial pressure is held constant. Tungsten hexacarbonyl supplies no oxygen and therefore requires a separate oxygen source for oxide films, but it is substantially more volatile and is used in metal and carbide CVD. Tungsten chlorides, including WCl₆ and WOCl₄, are lower-cost but introduce chloride residues that can corrode interconnect stacks and degrade dielectric reliability. Halogen-free precursors such as ethoxides avoid intentional chloride, but chloride can still enter as an impurity from packaging or process plumbing; the certificate of analysis should be reviewed with the same criticality as for WCl₆ when chloride-sensitive devices are produced.
| Precursor | Metal Oxidation State | Ligand Set | Halide Residue Risk | Volatility / Delivery | Oxide Stoichiometry Tendency |
|---|---|---|---|---|---|
| W(OC₂H₅)₅ | V | Five ethoxides | None from ligand, trace chloride possible | Low; direct liquid injection preferred | Reduced or oxygen-deficient WO₃−x |
| W(OC₂H₅)₆ | VI | Six ethoxides | None from ligand | Moderate; solution or vapor delivery | Stoichiometric WO₃ if oxidant used |
| W(CO)₆ | 0 | Six carbonyls | None from ligand | High; bubbler CVD possible | No oxygen unless co-reactant |
| WCl₆ / WOCl₄ | VI | Chlorides / oxychlorides | High | Low to moderate; corrosive HCl | Stoichiometric or chlorinated WO₃ |
Solvent compatibility must be tested before dilution at production scale. Hydrocarbons and ethers dried to ≤10 µg g⁻¹ water by activated 3A molecular sieves are generally acceptable carriers. Alcohols and glycols are reactive diluents because they participate in alkoxide exchange and accelerate condensation; they cannot be used as carriers. Contact surfaces should be glass, PTFE, or stainless steel. Methylene chloride and other chlorinated solvents can generate ethoxy-chlorotungsten species during extended contact and are not recommended unless compatibility data exist for the specific lot.
The first signature of moisture ingress is deepening of the brown-black color and a rise in viscosity, followed by precipitation of hydrolyzed tungsten oxide species. If the headspace dew point exceeds −40 °C during ampoule transfer, residual water is sufficient to initiate partial hydrolysis. Transfer should therefore occur in a glovebox with <1 ppm H₂O and <1 ppm O₂; fluoropolymer-lined caps are preferred, while rubber septa release moisture and plasticizers. Production-scale charging through a Schlenk line includes an argon sweep at 0.1–1.0 L min⁻¹ for 30 minutes before opening. The precursor may be warmed to 30–40 °C to reduce viscosity for transfer, but higher temperatures accelerate β-hydride elimination and release ethylene, ethanol, and acetaldehyde. At relative humidity above 20%, open handling is prohibited; all sampling must be performed under dry inert atmosphere. Waste quenching should be performed by slow addition to dry isopropanol under cold conditions, followed by aqueous neutralization, because direct addition of water generates an exothermic reaction and releases ethanol vapor.
In electrochromic or gas-sensor coating evaluations, W(OC₂H₅)₅ is typically screened at film thicknesses between 100 nm and 500 nm. Spectroscopic ellipsometry is used for thickness control, and adhesion is screened by cross-hatch tape test according to ASTM D3359-23. Because as-deposited films may contain reduced tungsten centers, optical modulation and carrier conductivity differ from films derived from W(VI) hexaethoxide; the process window must be rechecked after any precursor-lot change. Published data for this specific precursor configuration is limited, so manufacturing qualification should include X-ray photoelectron spectroscopy for W 4f oxidation-state distribution and sheet-resistance measurements before release.
