| HS Code | 721284 |
| Productname | Sodium Methoxide |
| Synonyms | Sodium methylate; Sodium methanolate; Methanol sodium salt |
| Chemicalformula | CH3ONa |
| Molecularweight | 54.02 g/mol |
| Casnumber | 124-41-4 |
| Ecnumber | 204-699-5 |
| Unnumber | 1431 (anhydrous) |
| Appearance | White to yellowish powder or solid |
| Odor | Odorless to alcohol-like |
| Physicalstate | Solid (anhydrous); commonly supplied as a solution in methanol |
| Meltingpoint | >300 °C (decomposes) |
| Density | 0.945 g/cm³ |
| Solubility | Soluble in methanol and ethanol; reacts with water |
| Ph | Strongly alkaline in solution |
| Reactivity | Reacts violently with water, acids, and oxidizing agents |
| Storageconditions | Store in a cool, dry, well-ventilated place away from moisture, acids, and oxidizers |
| Hazardclassification | Flammable solid; corrosive; water-reactive |
| Purity | Typically ≥95% for anhydrous powder; 25–30% in methanol solution |
| Decompositiontemperature | >300 °C |
As an accredited Sodium Methoxide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sodium Methoxide supplied in sealed, moisture-resistant 25 kg drums, clearly labeled corrosive, flammable, and protected from moisture and ignition sources. |
| Container Loading (20′ FCL) | Sodium Methoxide, UN 1431, palletized in sealed drums, loaded into 20′ FCL, secured, kept dry, hazard-labeled, away from ignition. |
| Shipping | Sodium Methoxide (Sodium methylate) is shipped as a hazardous material: UN 1431, Class 4.2 (spontaneously combustible), subsidiary Class 8 (corrosive), Packing Group II. It requires UN-spec packaging, appropriate hazard labels/placards, and segregation from water, acids, and oxidizers. Follow DOT, IMDG, and IATA regulations; keep dry and away from ignition sources. |
| Storage | Store sodium methoxide in a cool, dry, well-ventilated area, away from water, moisture, acids, and oxidizing agents. Keep containers tightly closed, protected from air, and use inert gas blanketing if possible. It reacts violently with water and is corrosive, so handle under dry conditions. Keep away from heat, sparks, and flames. Store separately from incompatible materials in labeled containers. |
| Shelf Life | Sodium methoxide shelf life: about 1–2 years if kept dry, sealed, and under inert gas; moisture and air cause degradation. |
In continuous methyl ester production, sodium methoxide is charged as a 25–30 wt% methanolic solution rather than as solid alkoxide to avoid localised overheating and to permit mass-flow metering into the oil-methanol stream. The dominant process conflict is water sensitivity: hydrolysis of methoxide to sodium hydroxide becomes measurable when feedstock water exceeds 0.25 wt%, and free fatty acid levels above 0.5 wt% consume catalyst stoichiometrically. The reaction is run in a multi-stage continuous stirred-tank train with 55–65 °C reactor temperature, atmospheric pressure, 6:1–9:1 methanol-to-oil molar ratio, and catalyst dosing of 0.5–1.3 wt% of oil feed as the 25–30 wt% methanolic solution. Each stage is sized for 45–90 min residence time, and the resulting methyl ester phase is separated from glycerol by decanter centrifuge or disc stack separator. After separation, the ester phase is washed with 5–10 vol% water at 60 °C, dried at 10–30 mbar and 90–110 °C, and stabilised with an antioxidant. The production-scale failure modes observed in this sequence are soap-stabilised emulsions during washing, glycerol carry-over when centrifuge backpressure exceeds the manufacturer’s design point, and incomplete phase splitting when the feedstock has residual phospholipids above 10 mg/kg phosphorus. Compliance for the final methyl ester is confirmed against EN 14214 and ASTM D6751: ester content is measured by EN 14103, acid number by EN 14104 or ASTM D664, total glycerol by EN 14105 or ASTM D6584, water by EN ISO 12937, oxidation stability by EN 14112, and cold soak filtration by ASTM D7501.
| Parameter | EN 14214 limit | ASTM D6751 limit | Test method |
|---|---|---|---|
| Ester content | 96.5 wt% min | Not specified | EN 14103 |
| Total glycerol | 0.25 wt% max | 0.240 wt% max | EN 14105, ASTM D6584 |
| Acid number | 0.50 mg KOH/g max | 0.50 mg KOH/g max | EN 14104, ASTM D664 |
| Water | 500 mg/kg max | Water and sediment 0.050 vol% max | EN ISO 12937, ASTM D2709 |
| Oxidation stability | 8 h min at 110 °C | 3 h min | EN 14112 |
Temperature control is not a broad convenience but a narrow processing window: below 55 °C the transesterification rate falls because the reaction mixture is mass-transfer limited, while above 65 °C atmospheric methanol reflux increases the vapour load on the condenser and can push the reactor toward pressure relief unless the methanol feed rate is reduced. The soap formation plateau becomes acute when feedstock water and free fatty acid combine to exceed the methoxide equivalent; the resulting sodium carboxylate behaves as an emulsifier during the water wash step and raises the time to phase separation from 2–4 h to more than 12 h in horizontal decanters.
In pharmaceutical intermediate production, sodium methoxide is used in methoxide-mediated cyclisations, condensations, and dehydrohalogenation steps for heterocyclic scaffolds. The kinetic role is base-promoted abstraction of an acidic proton followed by ring closure or substitution. Residual water changes the active species from methoxide to hydroxide, alters the hydrolysis pathway, and reduces the effective molarity of the alkoxide. Published data for proprietary API stoichiometries is limited, but the common operating window is 1.0–1.3 molar equivalents of sodium methoxide relative to the substrate acidic proton, with reaction temperature between −5 °C and 25 °C for exothermic condensation steps. The process is run in glass-lined or Hastelloy C-22 reactors because methanolic sodium methoxide is corrosive to unprotected carbon steel. The reactor is inerted with nitrogen, and the substrate in methanol, tetrahydrofuran, or dimethylformamide is metered below the surface to control exotherm. After an endpoint by HPLC area %, the reaction is quenched with acetic acid or aqueous ammonium chloride to pH 6.5–7.5, concentrated under vacuum at 40–60 °C, and washed with water to remove sodium salts. Conductivity of the organic phase is reduced below 10 µS/cm before crystallisation or distillation. Residual methanol is controlled under ICH Q3C Class 2 limits: permitted daily exposure of 30 mg/day and concentration limit of 3000 ppm in the final drug substance. Equipment cleaning validation and reaction time limits are governed by 21 CFR 211.67, 21 CFR 211.110, and ICH Q7 for active pharmaceutical ingredient manufacturing.
| Solvent | ICH Q3C Class | Permitted daily exposure | Concentration limit |
|---|---|---|---|
| Methanol | Class 2 | 30 mg/day | 3000 ppm |
| Tetrahydrofuran | Class 2 | 7.2 mg/day | 720 ppm |
| Dimethylformamide | Class 2 | 8.8 mg/day | 880 ppm |
Batch-to-batch variance in these reactions has been traced to methanol moisture content and substrate water levels rather than to alkoxide purity. The methanolic solution is therefore purchased with water below 0.2 wt% and sodium carbonate below 0.1 wt%; drums are blanketed with nitrogen and heated transfer lines are used where ambient storage falls below 10 °C to prevent crystallisation.
Agrochemical intermediate synthesis uses sodium methoxide primarily as a dehydrohalogenation and methoxylation agent in chlorinated heterocycle routes, including pyrimidine, triazine, and pyrazole building blocks for herbicides and fungicides. In a typical batch, a chlorinated heteroaromatic substrate is dissolved in toluene, dimethylacetamide, or dimethoxyethane, and a 25–30 wt% methanolic sodium methoxide solution is metered at 1.0–1.2 molar equivalents per displaceable chlorine or acidic proton. Reaction temperature is held between 30 °C and 80 °C, and sodium chloride precipitation is used as an in-process indicator of substitution progress. The slurry is filtered through a pressure nutsche or centrifugal filter, the mother liquor is washed with water, and the organic phase is concentrated by vacuum distillation at 0.5–10 mbar. Solvent moisture is kept below 0.05 wt% before alkoxide addition because hydrolysis to sodium hydroxide alters regioselectivity and increases aqueous-soluble by-product formation. Vent streams from the reactor are routed through a packed column scrubber or chilled condenser to keep methanol workplace exposure below the OSHA 1910.1000 Table Z-1 limit of 200 ppm TWA and 250 ppm STEL. Terminal products include substituted heterocyclic intermediates for sulfonylurea and pyrimidinyl carbinol classes; published process data for specific proprietary active ingredients is limited, and optimisation is normally performed at pilot scale using reaction calorimetry to map total exotherm and maximum heat release rate.
The nucleophilic displacement of chloride from 1-chloroanthraquinone by methoxide ion is performed in a glass-lined or stainless steel reactor at 60–80 °C using a 25–30 wt% sodium methoxide methanol solution at 1.1–1.3 molar equivalents. The formed sodium chloride is removed by filtration after the reaction mixture is cooled to 15–25 °C, and the product is isolated by drowning into 5–10 volumes of demineralised water. The precipitate is washed to neutral pH and dried at 60–80 °C under vacuum. Released chloride in the wet cake is reduced below 0.2 wt%, and the methoxy derivative is controlled at 98.5% HPLC area purity at 254 nm. This substitution is sensitive to water: if moisture rises above 0.3 wt% in the methanol feed, the competing hydrolysis product increases and the filtration rate slows because of hydroxide-initiated side reactions. Production-scale batches use indirect steam heating and methanol reflux; local exhaust ventilation is required at the drying and milling stages. The resulting methoxy-substituted anthraquinone is a downstream intermediate for disperse dye synthesis, where it is subsequently subjected to nitration, amination, or sulfonation depending on the final dye structure.
Methyl ester intermediates generated with sodium methoxide are subsequently hydrogenated to fatty alcohols in slurry-phase fixed-bed reactors using copper chromite or copper-zinc oxide catalysts at 200–300 °C and 20–30 MPa hydrogen pressure. In this route the upstream methyl ester quality directly controls catalyst cycle length and pressure-drop behaviour in the hydrogenation unit. Ester phases intended for fatty alcohol production are specified with methyl ester purity above 98.5 wt%, monoglyceride and diglyceride content below 0.1 wt%, acid number below 0.50 mg KOH/g, saponification value in the 180–200 mg KOH/g range, and sodium residue below 5 mg/kg after acidulation and water washing. Residual sodium methoxide not removed from the methyl ester deactivates copper-based hydrogenation catalysts, and the resulting pressure-drop increase across the fixed-bed reactor is a recognised production bottleneck. The methyl ester is produced from palm oil, rapeseed oil, or tallow using the same transesterification route as biodiesel, but the washing and drying steps are run to tighter water limits because water carry-over into the hydrogenation feed reduces catalyst activity. Hydrogenation is monitored by gas chromatography per ISO 12966-2, and the distilled fatty alcohol is controlled by hydroxyl value and hydrocarbon content against the relevant oleochemical specification.
Fatty acid methyl esters derived from soybean or rapeseed oil are transesterified with trimethylolpropane or pentaerythritol in the presence of sodium methoxide to produce polyol ester basestocks for biodegradable hydraulic fluids and compressor lubricants. The conversion is equilibrium-limited by methanol removal, so the reactor is operated at 130–180 °C under 10–30 mbar absolute pressure with nitrogen sparging. Sodium methoxide is charged at 0.1–0.3 wt% based on the methyl ester feed, and the liberated methanol is condensed and collected to monitor rate. The reaction endpoint is determined by hydroxyl value and acid value rather than by pressure recovery alone. Once hydroxyl value falls below the specification, the catalyst is neutralised with citric acid at 0.05–0.2 wt%, and the mixture is filtered through a plate filter precoated with diatomaceous earth. Incomplete neutralisation leaves alkaline sodium residues that accelerate ester hydrolysis during storage; over-neutralisation generates citrate salts that increase filtration pressure and reduce throughput. The finished polyol ester is controlled by kinematic viscosity at 40 °C between 30 mm²/s and 60 mm²/s, pour point below −20 °C, acid number below 0.50 mg KOH/g, and water below 300 mg/kg. Conformance for hydraulic fluid base stocks is assessed against ISO 15380 and the relevant ASTM D445 viscosity method, while the fatty acid methyl ester precursor is controlled by EN 14103 ester content and EN 14105 glyceride limits.
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Sodium methoxide (sodium methylate, CH₃ONa, CAS 124-41-4) is supplied as a white to off-white hygroscopic solid and as a methanolic solution at nominal concentrations of 25 wt% or 30 wt%. The solid has a molecular weight of 54.02 g/mol. The 30 wt% solution has a density of approximately 0.94–0.97 g/cm³ at 20 °C when measured by ASTM D4052, and the methanolic carrier gives the liquid form a closed-cup flash point below 15 °C by ASTM D93. The material hydrolyzes rapidly upon contact with water to methanol and sodium hydroxide, and it reacts with atmospheric carbon dioxide to form sodium carbonate. Industrial handling therefore uses closed feed systems with dry nitrogen blanketing. In these forms, sodium methoxide acts as both a methoxide donor and a strong condensation catalyst in methyl ester, pharmaceutical intermediate, and agrochemical synthesis.
The product is offered under representative designations such as SM-99 solid, SMS-25, and SMS-30. The solid grade is specified primarily by total alkalinity, sodium hydroxide, sodium carbonate, water, and methanol-insoluble matter. Solution grades are specified within a concentration window because the sodium methoxide content directly determines catalyst charge per unit oil feed. For pharmaceutical or moisture-sensitive syntheses, the lower sodium hydroxide and carbonate limits in solution grades reduce side reactions with acid-labile intermediates. Vendor technical bulletins commonly list the following as typical release limits.
| Parameter | SM-99 Solid | SMS-25 Solution | SMS-30 Solution |
|---|---|---|---|
| Physical state | White to off-white powder | Clear to slightly turbid liquid | Clear to slightly turbid liquid |
| Total alkalinity as CH₃ONa | ≥99.0 wt% | 24.5–25.5 wt% | 28.5–31.0 wt% |
| Sodium hydroxide | ≤1.0 wt% | ≤0.5 wt% | ≤0.5 wt% |
| Sodium carbonate | ≤0.5 wt% | ≤0.2 wt% | ≤0.2 wt% |
| Water | ≤0.5 wt% | ≤0.3 wt% | ≤0.3 wt% |
| Methanol insoluble matter | ≤0.1 wt% | Not applicable | Not applicable |
Total alkalinity, sodium hydroxide, sodium carbonate, and water are determined by non-aqueous titration, ion chromatography, and Karl Fischer titration according to supplier release methods. The solid grade is typically packaged in moisture-excluding fiber drums with polyethylene liners under nitrogen, while methanolic solutions are shipped in 200 L stainless steel drums or dedicated bulk tanks. Filtration of solution grades through 5 µm cartridge filters is common before charging to glass-lined reactors.
Solid sodium methoxide is selected when the process solvent is not methanol or when methanol addition must be minimized. The solution grades are preferred for methyl ester production because the methanol carrier aligns with the transesterification reaction and permits direct metering into the oil feed. Solid grade requires solvent dilution before use, but it avoids transporting and storing additional methanol inventory at the end-user site. Selection between the two forms therefore depends on whether the process can tolerate the methanol load and on local flammable liquid storage restrictions.
In transesterification, sodium methoxide is charged into the oil/methanol reaction loop as a 25 wt% to 30 wt% methanolic solution at catalyst doses of 0.5–1.5 wt% relative to oil mass. The methanol-to-oil molar ratio is commonly held at 6:1, with reactor temperature 60–65 °C and residence time 1–2 h in a continuous stirred-tank reactor or a plug-flow static mixer system. Because the methoxide ion is pre-formed, the reaction avoids the water release associated with sodium hydroxide dissolution and reduces soap formation; the resulting glycerol phase separates more rapidly and the crude methyl ester passes through water washing and vacuum drying before final filtration. Compliance with ASTM D6751 requires total glycerol below 0.24 wt%, free glycerol below 0.02 wt%, and acid number no greater than 0.50 mg KOH/g per ASTM D664. EN 14214 requires ester content no less than 96.5% and limits the sum of sodium plus potassium to 5 mg/kg in the final fuel.
For condensation reactions, the reagent is used at a 1.05–1.20 molar ratio relative to the electrophilic substrate, with the reaction temperature maintained below 40 °C in glass-lined reactors when volatile intermediates are present. The absence of aqueous hydroxide reduces ester hydrolysis; however, residual water above 0.3 wt% in the solution can still quench the alkoxide and generate sodium hydroxide, shifting selectivity. Reaction monitoring by gas chromatography with area normalization is typical, and endpoint conversion is confirmed by chromatographic disappearance of the limiting substrate.
For pharmaceutical intermediate synthesis, methanolic sodium methoxide is often added to a methanolic substrate slurry in glass-lined reactors under nitrogen at 0–10 °C to control exotherm, then warmed to 20–40 °C. The product supports methoxylation of heteroaromatic chlorides, ring closure, and carbonyl condensation. Residual sodium hydroxide and sodium carbonate are controlled to ≤0.5 wt% and ≤0.2 wt% respectively because these impurities can hydrolyze acid-labile substrates or consume reagent. In agrochemical synthesis, the same 30 wt% solution is used for O-methylation and enolate generation; batch-to-batch variance in water content above 0.3 wt% has been observed to shift endpoint pH and reduce isolated yield on production-scale campaigns, so drums are sampled and titrated before charging.
Relative to sodium hydroxide, sodium methoxide enters the transesterification loop as a pre-formed methoxide ion, so the catalyst stream contributes no water. Aqueous sodium hydroxide generates water during neutralization and increases soap formation; it also produces a heavier glycerol phase and requires additional washing to meet ASTM D6751 sodium-plus-potassium limits. Sodium methoxide is less hygroscopic than solid potassium methoxide and is typically selected when cost per mole of methoxide is critical in methyl ester production. Potassium methoxide is used where higher solubility of potassium soaps and faster reaction rates are required, but it can leave higher potassium residues in the final methyl ester if washing is incomplete. Sodium ethoxide transfers an ethoxide group and is selected for ethyl ester synthesis or for substrates requiring lower nucleophilicity; it is not directly interchangeable with sodium methoxide in methyl ester processes because the alkyl group must match the ester product to avoid mixed ester formation.
| Property | Sodium Methoxide | Potassium Methoxide | Sodium Ethoxide | Aqueous Sodium Hydroxide |
|---|---|---|---|---|
| Molecular weight | 54.02 g/mol | 70.13 g/mol | 68.05 g/mol | 40.00 g/mol |
| Active species | CH₃O⁻ | CH₃O⁻ | C₂H₅O⁻ | OH⁻ |
| Typical commercial form | Solid or 25–30 wt% methanol solution | 25–32 wt% methanol solution | Solid or 21 wt% ethanol solution | 50 wt% aqueous solution |
| Water contribution to reaction | None if dry | None if dry | None if dry | High |
| Primary use | Methyl ester production, methylations | Fast methyl ester production | Ethyl ester production, ethoxylations | Neutralization, general saponification |
| Biodiesel residue limit | Sodium ≤5 mg/kg under EN 14214 | Potassium ≤5 mg/kg under EN 14214 | Not applicable for methyl ester | Sodium ≤5 mg/kg under EN 14214 |
Published quantitative kinetic comparisons between these alkoxide salts under identical feedstock conditions are limited. Selection is normally determined by trial in a 100 L pilot reactor with measurement of conversion, soap content, and phase separation time.
Dry nitrogen blanketing is required because sodium methoxide reacts with atmospheric moisture to release methanol and form sodium hydroxide, and with carbon dioxide to form sodium carbonate. Bulk storage tanks are constructed of SS316L or glass-lined carbon steel; aluminum, zinc, magnesium, and copper alloys are not used because the alkoxide attacks these metals or catalyzes hydrogen formation. Methanolic solutions are flammable liquids with a flash point below 15 °C, so transfer pumps, flow meters, and valves are specified for explosion-proof service, and equipment is grounded and bonded. For solid material, dispensing rooms are maintained below 60% RH; exposure to water produces exothermic hydrolysis. The product is incompatible with strong acids, acid chlorides, and halogenated solvents, especially chloroform and carbon tetrachloride, with which violent decomposition can occur. Sodium methoxide should not be charged to a reactor containing residual water or acidic wash solvent.
In a continuous biodiesel unit, the replacement of solid sodium methoxide flake with 30 wt% methanolic solution changes both catalyst handling and methanol inventory. Solid flake requires a dilution skid with methanol and a mixing vessel; solution grade can be metered directly into the oil feed with positive-displacement diaphragm pumps or Coriolis mass flow controllers. Because the solution density at 20 °C is between 0.94 g/cm³ and 0.97 g/cm³, mass flow calibration differs from volumetric dosing, and the methanol carrier contributes 0.70 kg of methanol per 1.0 kg of solution at 30 wt%. Process control must account for this additional methanol in the molar ratio; otherwise excess methanol can raise distillation load and increase glycerol solubility in the ester phase. In a 5,000 L/h oil feed line, a static mixer with 10–14 elements is typically used to disperse the catalyst before the first reactor stage; pressure drop is monitored continuously because carbonate particles above 5 µm can accumulate on mixer elements and reduce dispersion. When the sodium hydroxide content of the incoming solution drifts above 0.5 wt%, soap levels in the crude methyl ester increase, and the decanter residence time must be extended beyond 30 min to achieve clean glycerol separation. Published data for this specific configuration is limited, but vendor technical bulletins recommend pre-filtration through 10 µm bag filters and daily titration of total alkalinity.
Regulatory control of methanolic sodium methoxide is governed by REACH registration for industrial and professional use; the methanolic solution is classified as flammable liquid category 2, skin corrosion category 1B, and specific target organ toxicity single exposure category 1. For pharmaceutical applications, methanol is controlled as a Class 2 solvent under ICH Q3C with a permitted daily exposure of 30 mg/day. Residual sodium and potassium in biodiesel are limited under EN 14214 to 5 mg/kg, and the final fuel must also pass oxidation stability and total contamination tests. Sodium methoxide is not an FDA-listed direct food additive; any use in food-contact synthesis requires removal or conversion to permitted residues.
