| HS Code | 110710 |
| Product Name | Sodium Ethoxide |
| Iupac Name | Sodium ethanolate |
| Synonyms | Sodium ethylate; Sodium ethanolate; NaOEt |
| Cas Number | 141-52-6 |
| Ec Number | 205-487-5 |
| Un Number | UN 3206 (solid); UN 1993 (solution) |
| Chemical Formula | C2H5ONa |
| Molecular Weight | 68.05 g/mol |
| Appearance | White to yellowish powder or solid |
| Odor | Alcohol-like |
| Physical State | Solid or ethanol solution |
| Melting Point | 260 °C |
| Boiling Point | Decomposes before boiling |
| Density | 0.868 g/cm³ at 25 °C (solution) |
| Solubility | Soluble in ethanol and methanol; reacts with water |
| Ph | Strongly alkaline (in solution) |
| Pka | Conjugate acid ethanol pKa ≈ 15.9 |
| Flash Point | 22 °C (closed cup, solution) |
| Hygroscopic | Yes |
| Storage Conditions | Store cool, dry, under inert gas, away from acids and oxidizers |
| Hazard Classification | Flammable, corrosive, causes severe skin burns and eye damage |
| Reactivity | Reacts violently with water, acids, and oxidizing agents |
| Smiles | CC[O-].[Na+] |
| Inchi | InChI=1S/C2H6O.Na/c1-2-3;/h3H,2H2,1H3;/q;+1/p-1 |
| Pubchem Cid | 2723922 |
As an accredited Sodium Ethoxide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sodium Ethoxide, 100 g, sealed in a moisture-proof glass bottle under nitrogen, with corrosive and flammable hazard labels. |
| Container Loading (20′ FCL) | Sodium Ethoxide loaded into a 20-foot FCL container in sealed, moisture-proof drums, palletized/secured, complying with hazardous cargo and IMDG regulations. |
| Shipping | Sodium ethoxide is shipped as a hazardous material. Dry solid: UN 3206, Class 4.2 (self-heating), subsidiary Class 8, PG II. Ethanol solutions: UN 3274, Class 3 flammable liquid, subsidiary Class 8, PG II/III. It is moisture-sensitive; use sealed, moisture-proof packaging, inert atmosphere, and corrosive/flammable labels. |
| Storage | Store sodium ethoxide in a cool, dry, well-ventilated, fire-resistant area. Keep containers tightly closed, preferably under inert gas, and protect from moisture, water, acids, oxidizers, and heat. Use secondary containment and segregate from incompatible materials. Avoid static discharge; ground and bond containers during transfer. Do not store near water. Sodium ethoxide is flammable, corrosive, and moisture-sensitive. Always follow the SDS and local regulations. |
| Shelf Life | Sodium ethoxide shelf life: about 1–2 years when sealed, dry, cool, under inert gas; hygroscopic, moisture-sensitive, degrades by hydrolysis. |
The largest-volume fuel-related use of sodium ethoxide is in ethanol-based transesterification trains producing fatty acid ethyl esters from low-moisture, low-free-fatty-acid feedstocks. In a continuous stirred-tank battery fitted with external plate heat exchangers, a 21 wt% sodium ethoxide solution in ethanol is metered at 0.4–0.8 wt% of triglyceride mass to maintain an alkoxide-to-oil molar ratio between 0.8:1 and 1.2:1. The reaction is held at 70–75 °C and 0.2–0.5 MPa backpressure to suppress ethanol vapor formation. Pre-treatment must reduce free fatty acid content below 0.25 wt% and moisture below 0.1 wt%; sodium ethoxide hydrolyzes to sodium hydroxide and ethanol, and the sodium hydroxide saponifies triglycerides to soaps. High-acid feedstocks such as waste cooking oil require esterification before base catalysis; the acid-catalyzed step is typically run at 60–65 °C with 1.0–1.5 wt% sulfuric acid until free fatty acid falls below 0.5 wt%, followed by vacuum dehydration at 90–100 °C under 5–10 kPa or molecular sieve adsorption to reach the moisture specification. Soap generation increases acidulation load downstream and raises pressure drop across centrifugal separators. Published production-scale data show that oil-phase moisture above 0.3 wt% can depress ester conversion below 96.5%, the ester content minimum specified for fatty acid methyl ester in EN 14214 and frequently used as an internal specification for ethyl ester products in the absence of a separate FAEE standard. Residual sodium is removed by water washing and ion-exchange polishing, with a combined sodium and potassium concentration below 5 mg/kg as required by EN 14214; total glycerol under ASTM D6751 must remain below 0.240 wt%. The glycerol phase from ethanol-based trains contains more ethanol than methanol-based methyl ester processes; ethanol recovery by vacuum stripping at 80–90 °C is normally required to close the mass balance.
| Parameter | Control limit | Reference method |
|---|---|---|
| Free fatty acid | <0.25 wt% | AOCS Ca 5a-40 |
| Moisture | <0.1 wt% | ISO 12937 |
| Ester content after reaction | ≥96.5% | EN 14103 (adapted for ethyl esters) |
| Sodium/potassium | <5 mg/kg | EN 14108/EN 14109 |
| Total glycerol | <0.240 wt% | ASTM D6751 |
Pharmaceutical intermediate synthesis using sodium ethoxide is concentrated where an aqueous base would hydrolyze ester or nitrile groups before condensation can proceed. Substituted pyrazolones, barbituric acid derivatives, and sulfonamide precursors are typically prepared in ethanol or ethanol/toluene using sodium ethoxide at 18–21 wt%. The base is charged at 1.02–1.10 mol per mole of active methylene substrate under nitrogen, and the reaction mass is kept at 10–20 °C during the initial exotherm. Reflux condensers on these vessels are operated with brine at −10 °C to recover ethanol vapor and maintain solvent inventory while the exotherm is controlled. Glass-lined steel is common for acid resistance, but free sodium hydroxide generated through trace hydrolysis can etch the glass lining at elevated temperature; fluoropolymer-lined steel is therefore specified for extended campaigns. The central process conflict is competing aldol polymerization: when the substrate contains two alpha-carbonyl protons, local overfeed of sodium ethoxide produces dianion intermediates that oligomerize. Static mixers or loop recirculation feed systems are used to limit the temperature gradient to ≤5 °C across the reactor. Filtration of sodium chloride or sodium sulfate by-products is delayed until complete conversion because premature filtration can carry unreacted enolate into the waste stream. Residual sodium salts in the isolated intermediate are held below 0.1 wt% ash by washing with dilute acetic acid in ethanol. Moisture ingress above 0.05 wt% of reaction mass leads to incomplete deprotonation and generates sodium hydroxide, which saponifies esters and lowers API intermediate yield. Published data for specific yield in sulfonamide synthesis is limited because most reference formulations are confidential drug master file filings, but reactor monitoring generally follows temperature profile and infrared disappearance of the carbonyl band at 1740 cm⁻¹.
For ethyl acetoacetate production via Claisen self-condensation, dry ethyl acetate is charged to a jacketed glass-lined reactor, and sodium ethoxide powder is screw-fed at a rate that keeps the batch between 5 °C and 12 °C. The molar feed ratio is 1.05 mol sodium ethoxide per 1.00 mol ethyl acetate, with the small excess compensating for ethanol moisture and carbon dioxide contamination. The reactor agitator is specified for high-viscosity slurry service, typically a two-flight helical ribbon impeller at 30–60 rpm, because the sodium enolate intermediate can thicken the mass before acidification. After the addition, the batch is heated to 75–80 °C and held for 4–6 h, while ethanol by-product is distilled continuously to shift the equilibrium toward the beta-keto ester. The crude sodium enolate is acidified with 30 wt% sulfuric acid to pH 3.4–3.8. Phase separation at 45 °C yields crude ethyl acetoacetate in the upper organic layer; the lower aqueous phase is extracted with ethyl acetate to recover additional product and reduce chemical oxygen demand in wastewater. The product is dried by vacuum distillation at 2–5 kPa, and sodium sulfate content in the final product is kept below 0.1 wt%. Production-line failure modes include plugging of the sodium ethoxide screw feeder by atmospheric moisture, which forms a crust of sodium hydroxide and ethanol vapor. Carbon steel is avoided in the distillation step because residual acid and ethanol form acetic acid traces that corrode carbon steel at ≥80 °C. The process is incompatible with chlorinated solvent residues; chloroform reacts with sodium ethoxide to form dichlorocarbene, which can initiate an exothermic event exceeding 150 °C in adiabatic testing.
Pyrethroid acid intermediate production uses sodium ethoxide in Darzens glycidate condensation between substituted benzaldehydes and ethyl chloroacetate. The base solution is added to a mixture of the aldehyde and the chloroester in ethanol/toluene at −5 °C to 5 °C using a cryogenic brine jacket. The molar ratio of sodium ethoxide to ethyl chloroacetate is maintained at 1.02–1.08:1; excess base hydrolyzes the chloroester to glycolate salts. The feed line is jacketed and recirculated through a low-temperature heat exchanger to prevent localized alkoxide accumulation that would trigger aldol side reactions. The resulting glycidate is held at 0–5 °C for 3–5 h, then quenched with 10 wt% acetic acid to pH 6.8–7.2. Chloride by-product is removed by water washing at 10 °C, and the organic phase is concentrated at 40 °C under 8–10 kPa to avoid thermal rearrangement of the epoxide. Industrial specifications for the glycidate intermediate frequently require ≥98 area% by gas chromatography and residual epoxide stability below 0.5% degradation after 48 h at 25 °C. The process is incompatible with free acid and with chlorinated solvent residues; chloroform reacts with the alkoxide to generate dichlorocarbene, which can decompose the glycidate exothermically. Process vessels are inerted with nitrogen, and the nitrogen purge is maintained at 0.1–0.3 m³/h per cubic metre of reactor volume to exclude carbon dioxide and moisture.
Sodium ethoxide functions as a monofunctional initiator in the ring-opening polymerization of ethylene oxide to produce polyethylene glycol monoethyl ethers with controlled molar mass. The initiator is prepared in situ by dissolving sodium ethoxide in dry tetrahydrofuran or toluene, and the reactor is sealed and pressure-tested to 0.6 MPa before ethylene oxide is metered. The reactor is purged with nitrogen to an oxygen concentration below 0.5 vol% because oxygen can form explosive peroxides with ethylene oxide. Polymerization is conducted at 80–110 °C and 0.2–0.4 MPa, with ethylene oxide feed limited to avoid accumulation of unreacted oxide. Molar mass is controlled by the ethylene oxide-to-sodium ethoxide ratio; for a target number-average molar mass of 350 g/mol, the feed ratio is approximately 7 mol ethylene oxide per 1 mol sodium ethoxide after correcting for moisture. Hydroxyl value measured by ASTM D4274 is used to track molar mass; a target 350 g/mol product corresponds to approximately 160 mg KOH/g. Moisture and ethanol act as chain-transfer agents, so reactor feed specifications limit water to ≤100 mg/kg and ethanol to ≤0.1 wt%. Residual ethylene oxide in the product is reduced by nitrogen sparging at 60 °C until the headspace concentration is below 1 mg/kg, measured by headspace gas chromatography. Reaction vessels are clad stainless steel with rupture-disk protection; the runaway exotherm from ethylene oxide homopolymerization can exceed 200 °C in adiabatic calorimetry, so the cooling system is designed for a heat-transfer coefficient of 300–500 W/(m²·K) at maximum agitation. The resulting monoethyl polyglycols are used as wetting agents and as intermediates for ethoxylated surfactants.
In the synthesis of benzophenone-class UV absorbers and coumarin-type optical brightener precursors, sodium ethoxide promotes base-catalyzed condensation between substituted benzaldehydes and active methylene compounds. The reaction is carried out in ethanol at 50–60 °C, with a 21 wt% sodium ethoxide solution added over 2 h using a metering pump controlled by reactor temperature. After condensation, the batch is neutralized with acetic acid, and the product is isolated by filtration at 20 °C. The filter cake is washed with deionized water until residual sodium in the product is below 50 mg/kg, measured by inductively coupled plasma optical emission spectrometry after acid digestion, to prevent haze in the final polymer formulation. Process variability is mainly governed by moisture in the aldehyde feed; water above 0.2 wt% reduces the condensation rate and increases the formation of aldol dimer impurities. For coumarin-type brighteners, the same alkoxide concentration is used but the addition temperature is lowered to 30–35 °C to limit base-catalyzed ring opening of the lactone intermediate.
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Sodium ethoxide (sodium ethanolate, CAS 141-52-6, EINECS 205-487-5) is supplied as an alkoxide base in two principal forms: a free-flowing solid with typical active content in the range 96–99% by non-aqueous acid-base titration, and an anhydrous ethanolic solution with assay of 20.0–22.0% (w/w). The molecular formula C₂H₅ONa corresponds to a formula weight of 68.05 g/mol. The 21% solution is the more common reactor feed because it permits closed-system metering, reduces dust exposure during charging, and eliminates the dissolution exotherm associated with solid addition to ethanol. Fresh solution is a clear to slightly turbid liquid with Pt-Co color normally held below 100 APHA units. Free sodium hydroxide is limited to 0.5–1.0% (as NaOH) because excess hydroxide shifts stoichiometry and increases soap or hydrolysis byproducts in downstream operations. Residual moisture is controlled below 0.5% to limit hydrolysis to sodium hydroxide and ethanol, and the resulting caustic load must be included in neutralization calculations. The product must be kept under dry nitrogen; carbon dioxide contact precipitates carbonate species and lowers active alkoxide content. Solid material is hygroscopic and should be handled in closed transfer systems or under inert gas when relative humidity exceeds 60%.
Alkoxide selection is governed by conjugate alcohol pKa, nucleophile size, and solvent compatibility. Sodium ethoxide in ethanol has a conjugate acid pKa of 15.9, compared with 15.5 for methanol and 19.2 for tert-butanol. This places sodium ethoxide between sodium methoxide and potassium tert-butoxide in both basicity and steric demand. In ethyl ester condensations, ethoxide is sufficiently basic to deprotonate the α-carbon of ethyl esters while avoiding the high steric hindrance that slows attack by tert-butoxide on carbonyl centers. Unlike sodium methoxide, sodium ethoxide does not introduce methoxide-derived methyl ester contamination when ethanol is the process solvent. The comparison is summarized in Table 1.
| Parameter | Sodium Methoxide | Sodium Ethoxide | Potassium tert-Butoxide |
|---|---|---|---|
| Molecular weight | 54.02 g/mol | 68.05 g/mol | 112.21 g/mol |
| Conjugate alcohol pKa | 15.5 | 15.9 | 19.2 |
| Typical commercial solution | 25–30% in methanol | 21% in ethanol | 1.0 M in tetrahydrofuran or solid |
| Relative steric demand | Low | Moderate | High |
| Common solvent system | Methanol | Ethanol | THF, DMSO, diethyl ether |
For production lines already configured for ethanol distillation, sodium ethoxide avoids methanol handling and mixed-solvent recovery. However, potassium tert-butoxide may be required when a more aggressive base is needed for deprotonation of weakly acidic substrates or when reactions are run in tetrahydrofuran or dimethyl sulfoxide. Published data for the specific process configuration must be generated at pilot scale because the optimum base cannot be assigned solely from pKa values.
Pharmaceutical intermediate synthesis and fine-chemical operations use sodium ethoxide in Claisen condensations, Dieckmann cyclizations, and nucleophilic aromatic substitutions. In a representative batch Claisen condensation of ethyl acetate to ethyl acetoacetate, a 21% sodium ethoxide solution is charged below the liquid surface of a dried glass-lined reactor containing ethyl acetate. The addition is performed over 45–120 min with jacket temperature controlled at 75–80°C; the condensation is exothermic, and the reactor is held within ±2°C by split-range control of the condenser and jacket. Overhead ethanol is removed continuously or intermittently to shift equilibrium. After condensation, the reaction mass is neutralized with acetic acid to pH 6.5–7.5, and ethyl acetoacetate is recovered by vacuum distillation at 60–80 mbar. Batch-to-batch variation in free sodium hydroxide above 1.0% increases color body formation and yield loss because the hydroxide catalyzes competing aldol condensation. Production-scale lines therefore titrate each lot before charging and adjust the stoichiometric ratio by 0.5–1.0 mol%.In nucleophilic aromatic substitution reactions, sodium ethoxide is used to displace activated halides. The reaction is typically conducted under reflux in ethanol at 78–82°C; the substrate must be dry, and the base is charged in slight excess of 1.05–1.10 molar equivalents to compensate for water-induced hydrolysis. Agitation is maintained at 200–300 rpm in glass-lined vessels with retreat-curve impellers because poor mixing produces localized alkoxide concentration and increases hydrolysis products. The work-up involves cooling to 20–25°C and acidification with dilute hydrochloric acid; excess ethoxide is quenched under temperature control to keep the exotherm below 30°C. Continuous reactors for this class of condensation have been described, but published data for direct substitution of the batch process is limited; residence time and byproduct rejection must be validated on the specific feedstock.
Sodium ethoxide is selected for transesterification of triglycerides when fatty acid ethyl esters are specified and residual methanol content must be avoided. A 21% ethanolic solution is metered into dry oil at catalyst loadings of 0.5–1.5 wt% of oil mass. The reaction is held at 60–80°C in a closed stirred vessel with ethanol reflux. Total water in the oil/ethanol mixture is kept below 0.3–0.5 wt% because water hydrolyzes the alkoxide to sodium hydroxide and ethanol; the hydroxide then promotes saponification of free fatty acids and leads to emulsified product layers. Free fatty acid content of the feedstock is determined by titration according to ISO 660; oils with acid value above 2.0 mg KOH/g may require pre-neutralization or caustic compensation. In continuous plants, the catalyst solution is premixed with dry ethanol and injected through a static mixer into the oil feed; residence time is maintained at 15–45 min in a plug-flow reactor at 70–80°C. The ethyl ester product is washed with acidified water or treated with adsorbents to remove sodium salts. Water washing is conducted at 50–60°C to prevent emulsion stabilization by soap.
For this application, sodium methoxide is often interchangeable on a mass basis, but ethoxide eliminates methanol contamination in the product and in the recovered alcohol stream. Potassium tert-butoxide is not preferred because of higher cost and lower catalytic efficiency in ethanol at the same molar loading. The operational boundary is moisture: when ambient relative humidity exceeds 60%, storage and charging must be closed-loop, and the oil must be vacuum-dried at 80–90°C and 50–70 mbar before catalyst addition. Process equipment should avoid copper and zinc alloys because alkoxide solutions are corrosive to these metals; 316L stainless steel or glass-lined construction is used.
Sodium ethoxide is classified as flammable and corrosive. The 21% ethanolic solution carries a closed-cup flash point near 13°C; the vapor phase above the liquid remains flammable at normal handling temperatures and requires explosion-proof electrical equipment. GHS classification includes H225 for highly flammable liquid and H314 for severe skin burns and eye damage. Solid sodium ethoxide reacts exothermically with water, generating ethanol and sodium hydroxide; under confined conditions the heat release is sufficient to ignite nearby flammable vapors if the solid is not pre-diluted in dry ethanol. Storage containers must be closed, grounded, and blanketed with dry nitrogen at a pad pressure of 0.2–0.5 bar. The product must be kept away from aqueous acids, carbon dioxide, halogenated solvents, and strong oxidizers. Carbon dioxide in purge gas or headspace converts ethoxide to carbonate species, reducing active content and forming suspended solids that can block metering pumps and flow meters. Bulk tanks for the 21% solution are equipped with desiccant vent dryers or nitrogen makeup to exclude moisture. Because the solution is mildly viscous, lines feeding metering pumps should be sized for a velocity below 1.0 m/s to avoid cavitation at the pump inlet; progressive cavity or diaphragm pumps with PTFE or stainless steel wetted parts are used. Before maintenance, lines are flushed with dry ethanol and then water-neutralized to prevent residual alkoxide from causing burns or ignition on contact with moisture. Published data for large-scale storage failure rates is limited, but most operational incidents trace to water ingress through open manways or damaged nitrogen blanketing rather than to intrinsic chemical instability.The product is released against a specification that depends on the chosen model: solution grade or solid grade. Table 2 lists representative acceptance limits. The solution grade is packaged in 200 L steel drums or 1,000 L IBCs under nitrogen; the solid grade is packaged in 25 kg fiber drums with polyethylene liners. Incoming quality verification includes visual inspection, density measurement for the solution, and laboratory titration before release to production. Color is measured by ASTM D1209, moisture by ASTM E203, and density by ASTM D4052. Assay is determined by non-aqueous acid-base titration with a standardized hydrochloric acid solution in anhydrous isopropanol; the endpoint is selected to distinguish sodium hydroxide from sodium ethoxide. Sodium carbonate is measured by acid evolution or infrared spectroscopy, but the 0.5% water limit usually constrains carbonate formation.
| Property | 21% Solution limit | 96–99% Solid limit | Method |
|---|---|---|---|
| Assay (as C₂H₅ONa) | 20.0–22.0% w/w | 96.0–99.0% w/w | Non-aqueous titration |
| Free sodium hydroxide | ≤1.0% | ≤2.0% | Differential titration |
| Sodium carbonate | ≤1.0% | ≤1.0% | Acid evolution |
| Water | ≤0.5% | ≤0.5% | ASTM E203 |
| Color | ≤100 APHA | Not applicable | ASTM D1209 |
| Density at 25°C | 0.86–0.88 g/cm³ | Not applicable | ASTM D4052 |
Batch-to-batch variation in solid material is higher than in solution because grinding and packaging operations can introduce fines and surface moisture. Solid drums are therefore re-tested after transit if the tamper seal is broken or if the storage area experienced relative humidity above 60%. For critical pharmaceutical intermediates, a secondary supplier audit verifies that the alkoxide is produced under an ISO 9001 quality system and that cleaning procedures prevent cross-contact with sodium methoxide or potassium tert-butoxide, which would alter the alkoxide composition and downstream impurity profile. No single compendial monograph exists for sodium ethoxide; users therefore align the specification with the requirements of the specific reaction and validate method equivalency against retained reference lots.
