| HS Code | 946231 |
| Product Name | Potassium Methoxide |
| Iupac Name | Potassium methanolate |
| Synonyms | Potassium methanolate; Methanol potassium salt |
| Chemical Formula | CH3KO |
| Molecular Weight | 70.13 g/mol |
| Exact Mass | 69.9821 g/mol |
| Cas Registry Number | 865-33-8 |
| Ec Number | 212-736-1 |
| Appearance | White to off-white crystalline powder or colorless to pale yellow liquid (often in methanol solution) |
| Odor | Alcohol-like (especially as methanol solution) |
| Density | 0.95 g/mL at 20 °C (typical methanol solution) |
| Melting Point | 152-156 °C (pure solid) |
| Boiling Point | Decomposes before boiling |
| Solubility | Soluble in methanol and ethanol; reacts with water |
| Ph | Strongly alkaline in solution |
| Flash Point | 11 °C (methanol solution) |
| Autoignition Temperature | 455 °C (methanol solution) |
| Stability | Moisture-sensitive; reacts with water, acids, and oxidizing agents |
| Storage Conditions | Store under dry inert gas, away from moisture, acids, heat, and ignition sources |
| Hazard Class | Flammable liquid and corrosive |
| Un Number | 3274 (alcoholates solution, n.o.s., in alcohol) |
| Inchi | InChI=1S/CH3O.K/c1-2;/h1H3;/q-1;+1 |
| Smiles | [K+].[O-]C |
As an accredited Potassium Methoxide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Potassium Methoxide packaged in 25 kg airtight, corrosion-resistant steel drums, clearly labeled corrosive, moisture-sensitive, and hazardous for safe transport and storage. |
| Container Loading (20′ FCL) | Container loading for Potassium Methoxide (20′ FCL): palletized sealed drums, secured, moisture-protected, segregated, hazard-labeled, with compliant documentation for safe ocean transport. |
| Shipping | Potassium methoxide is typically shipped as a flammable, corrosive methanol solution under UN 3274, Alcoholates solution, n.o.s. (Potassium methoxide in methanol), Class 3, PG II, subsidiary Class 8. Use sealed, corrosion-resistant containers; keep away from water, acids, oxidizers, and ignition sources. |
| Storage | Store Potassium Methoxide in a cool, dry, well-ventilated, fireproof area away from heat, ignition sources, water, acids, oxidizers, and halogens. Keep containers tightly closed, moisture-proof, and preferably under inert gas. Use corrosion-resistant, clearly labeled containers. Segregate from incompatible materials. For methanol solutions, provide ventilation, grounding, spill containment, and appropriate PPE. Prevent contact with moisture and air. |
| Shelf Life | Potassium methoxide is moisture- and air-sensitive; store sealed under inert gas, cool and dry. Typical shelf life: 12–24 months unopened. |
Refined rapeseed and soybean oil streams entering alkaline transesterification with potassium methoxide solution are typically pre-treated to a free fatty acid level of ≤ 0.5 mg KOH/g and moisture content of ≤ 500 ppm; phosphorus and non-hydratable phosphatide concentrations are held below 10 ppm to prevent emulsified soap formation downstream. The catalyst addition ratio is not fixed solely by oil mass: the methoxide first neutralizes acidic compounds at a stoichiometric equivalence of approximately 1.25 g KOMe per 1 g KOH-equivalent acid value, and the remaining catalytically active fraction drives glyceride transesterification. For low-acid rapeseed oil, industrial dosing is 0.80–1.00 wt% of the oil mass when supplied as a 30–32 wt% methanolic solution; for soybean oil with phospholipid-derived acidity, the same solution is dosed at 0.90–1.20 wt%; for used cooking oil that has undergone acid-catalysed esterification to acid value 1.0–1.5 mg KOH/g, dosing rises to 1.20–1.50 wt%. The process operates as a two-stage continuous stirred-tank reactor train at 60–65 °C and atmospheric pressure, with a total residence time of 60–90 min; conversion is followed by inline viscosity and refractive index measurements because soap-stock accumulation can produce a viscosity inflection prior to visible gel formation. After reaction, the stream is neutralized with phosphoric or sulfuric acid to pH 5.0–6.5, and the glycerol-rich lower phase is separated in a disc-stack centrifuge with a feed temperature of 55–65 °C. A key production-scale failure mode in UCOME lines is the plugging of centrifuge bowl discharge channels when potassium soap concentration exceeds 1.8 wt% of the organic phase; this occurs when the acid value is not reduced below 1.5 mg KOH/g or when water ingress exceeds 0.3 wt%. Residual methanol is recovered by vacuum stripping at 65–70 °C and 35–50 kPa, followed by water washing, vacuum drying at 105–120 °C, and optional distillation under 0.5–2 kPa at 200–240 °C. The finished fatty acid methyl ester product is controlled under EN 14214:2012+A1:2014 Table 1, including ester content ≥ 96.5% (m/m), total glycerol ≤ 0.25% (m/m), monoglyceride ≤ 0.70% (m/m), and water ≤ 500 mg/kg; the corresponding U.S. specification is ASTM D6751-23, with additional process quality expectations under ISO 9001:2015 or BQ-9000 producer certification. Terminal downstream products are FAME biodiesel for distillate blending, 80–88 wt% crude glycerol as a co-product, and potassium phosphate/sulfate neutralization salts directed to fertilizer-stream recovery.
Loop-venturi alkoxylation trains processing linear C12–C14 fatty alcohol into nonionic surfactants use potassium methoxide solution (30–32 wt% in methanol) as an initiation catalyst, with catalyst loading expressed as weight percentage of the initial alcohol charge. For a 3 mol EO/mol alcohol target, the loading is 0.20–0.30 wt%; for 7 mol EO/mol alcohol the loading is 0.10–0.20 wt%; higher-mole adducts above 20 mol EO/mol alcohol are produced at 0.05–0.15 wt% because the propagation exotherm under potassium counterion conditions is more difficult to control as viscosity rises. The alcohol feed is first vacuum-stripped to water ≤ 0.05 wt% at 110–130 °C and 5–10 kPa, then charged to a nitrogen-blanketed stainless steel or glass-lined stirred autoclave and heated to 120–140 °C for C12–C14 short-chain adducts. Ethylene oxide is fed at 0.3–0.5 MPa partial pressure with jacket cooling capacity designed for a peak heat release of 90–110 kJ/mol EO; pressure-rise monitoring is used to stop the oxide feed if the headspace exceeds 0.55 MPa. After the oxide feed is completed, the alkoxide-terminated oligomer is digested at 130–150 °C until the reactor pressure stabilizes for 20–30 min, then quenched with 0.10–0.30 wt% acetic acid or lactic acid to a final product pH of 6.0–7.5. The neutralized product is cooled to 70–80 °C, filtered through 10 µm bag filtration, and transferred under nitrogen. Compliance with REACH Regulation (EC) No 1907/2006 requires that the product is registered for the intended use descriptors, while EU Detergent Regulation (EC) No 648/2004 applies to cleaning-product additives; biodegradability is assessed according to OECD 301B or OECD 301F. Terminal products include C12–C14 alcohol ethoxylates with HLB values from 7.5 to 15.0, C9–C11 alcohol ethoxylates used in rapid-wetting formulations, and methyl end-capped or sulfate-neutralized variants used in metalworking fluids, textile auxiliaries, and pesticide emulsifiers.
| Alcohol substrate | Target EO adduct | KOMe loading | Reactor temperature range | Post-neutralization pH |
|---|---|---|---|---|
| C12–C14 linear alcohol | 3 mol EO/mol | 0.20–0.30 wt% | 120–140 °C | 6.0–7.0 |
| C12–C14 linear alcohol | 7 mol EO/mol | 0.10–0.20 wt% | 130–150 °C | 6.0–7.5 |
| C9–C11 linear alcohol | 6–8 mol EO/mol | 0.10–0.25 wt% | 130–155 °C | 6.5–7.5 |
Potassium methoxide is selected over sodium methoxide in certain API intermediate synthetic routes when the potassium cation confers better low-temperature solubility in anhydrous methanol and when downstream phase-transfer steps are sensitive to sodium concentration. The application is not weight-percent based across all chemistries; dosing is expressed as molar equivalents relative to the limiting substrate. For selective O-methylation of a phenol-type heteroaromatic intermediate, addition is typically 1.05–1.20 molar equivalents in anhydrous methanol at 0–20 °C; for base-catalysed methanolysis of a methyl ester intermediate, the catalyst is reduced to 0.05–0.20 molar equivalents, with reaction monitoring by HPLC or GC because residual starting ester below 0.10 area% is often required before isolation. The process is executed in a glass-lined or Hastelloy C-276 reactor with a nitrogen sweep, a metered addition line rated for 30–32 wt% potassium methoxide solution, and jacket temperature control capable of holding the batch within ±5 °C of setpoint during the initial exotherm. Water content in methanol is controlled to ≤ 0.10 wt% to avoid alkaline hydrolysis competing with the desired methoxide pathway; the reaction is quenched with acetic or citric acid to pH 5.5–7.0, extracted, and concentrated under vacuum at 40–60 °C with a final crystallization or distillation. Compliance is governed by ICH Q7 for active pharmaceutical ingredient GMP, 21 CFR 210/211 where the material enters finished dosage form manufacture, and USP <467> for residual methanol; residual potassium and sodium are reported under the specific drug substance monograph or according to ICH Q3D elemental impurity risk assessment. Terminal products include methoxy-functionalized pyridine, pyrimidine, and benzimidazole sulfoxide intermediates, as well as steroid methyl ether intermediates used in subsequent anti-inflammatory and progesterone-related API synthesis.
Within methyl ester intermediate synthesis for pyrethroid acid moieties, potassium methoxide serves as a homogeneous transesterification catalyst between an ethyl chrysanthemate intermediate and anhydrous methanol. The catalyst is injected as a 30–32 wt% methanolic solution at 0.20–1.00 wt% of the ester–methanol feed mass, equivalent to approximately 0.05–0.20 molar equivalents relative to the ester substrate; higher loadings accelerate methoxide-initiated side reactions at the cyclopropane ring and are avoided unless the substrate is pre-purified to ≥ 99.0% isomer content. The transesterification is conducted at 0–20 °C under nitrogen in a stainless steel or glass-lined vessel, with methanol removed periodically under reduced pressure to drive the equilibrium toward the methyl ester; batch time is typically 2–5 h after catalyst addition. The mixture is neutralized with aqueous citric acid to pH 5.5–6.5, extracted with ethyl acetate or dichloromethane, dried over anhydrous sodium sulfate, and concentrated under reduced pressure at 35–45 °C; the crude methyl ester may be further purified by fractional distillation at 0.5–1.5 kPa. Compliance obligations for the intermediate are defined by REACH Regulation (EC) No 1907/2006 and, when intended for the EU formulated agrochemical market, by Regulation (EC) No 1107/2009 including the five-batch impurity profile; where relevant, tolerance specifications from FAO/WHO Joint Meeting on Pesticide Specifications apply to the finished formulation. Terminal downstream products include methyl chrysanthemate and permethrate methyl ester precursors for synthetic pyrethroids, methoxy-substituted aromatic acid esters used in herbicide intermediate packages, and methyl acetoacetate-derived intermediates for pyrazolone crop protection chemistry.
Potassium methoxide catalyses the transesterification of propylene carbonate with methanol to dimethyl carbonate and monopropylene glycol in a continuous reactive distillation configuration. The catalyst is injected as a 30–32 wt% methanolic solution at 0.10–0.50 wt% of the combined methanol–propylene carbonate feed; higher loadings are not used because the concurrent ring-opening side reaction to propylene oxide oligomers and the formation of potassium carbonate from carbon dioxide traces reduce selectivity. The feed methanol-to-propylene carbonate molar ratio is maintained at 4:1 to 6:1, with the reaction zone held at 70–90 °C and 0.1–0.3 MPa; the dimethyl carbonate–methanol azeotrope is withdrawn overhead and separated by pressure-swing distillation or extractive distillation, while propylene glycol leaves as a side product. Catalyst deactivation is monitored by the pressure drop across the reboiler and by the colour rise in the propylene glycol fraction; spent catalyst residues are removed by flash distillation at 120–140 °C under 1–5 kPa. Product dimethyl carbonate is controlled to a minimum purity of 99.5 wt%, water ≤ 100 ppm, and acidity ≤ 0.01 wt% as acetic acid; no single ISO product standard applies to all industrial DMC grades, so specifications are buyer-specific under REACH Regulation (EC) No 1907/2006 and, for battery-electrolyte applications, under supplier-controlled purity protocols. Terminal products include dimethyl carbonate used as a methylating and carbonylating reagent, monopropylene glycol for unsaturated polyester resin and antifreeze segments, and downstream polycarbonate intermediates.
Production of long-chain alkyl methacrylate monomers by transesterification of methyl methacrylate with fatty alcohols uses potassium methoxide as a homogeneous alkaline catalyst in a vacuum-stripped reactor system. The catalyst is charged at 0.20–1.00 wt% of the fatty alcohol/methyl methacrylate feed, with the lower range reserved for dodecyl alcohol and the upper range for stearyl or behenyl alcohol where mass-transfer and viscosity effects reduce catalyst effectiveness. The batch is stabilized with 500–1,000 ppm 4-methoxyphenol or hydroquinone monomethyl ether relative to total monomers to prevent radical polymerization during distillation; the methanol generated is removed as an azeotrope with methyl methacrylate at 50–70 °C under reduced pressure, shifting the equilibrium toward alkyl methacrylate. The reactor is equipped with a structured packing column, a reflux splitter, and an air sparge of 2–5 L/min per cubic metre of reactor volume; the reaction temperature is kept below 90 °C to suppress Michael addition side products. After conversion exceeds 95%, the catalyst is neutralized with sulfuric acid or citric acid, washed with brine, and the product is distilled at 0.1–0.5 kPa to remove unreacted methyl methacrylate and fatty alcohol. Compliance is established under REACH Regulation (EC) No 1907/2006, with the finished monomer tested for viscosity by ASTM D445-21, acid number by ASTM D974-22, and purity by GC-FID; for UV-curable coatings, residual peroxide and inhibitor levels are specified by the formulator. Terminal products include lauryl methacrylate, stearyl methacrylate, and behenyl methacrylate monomers used in industrial coatings, pressure-sensitive adhesives, and oil-absorbing polymer particles.
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Potassium methoxide (CH3OK, CAS 865-33-8, molecular weight 70.13 g/mol) is an alkali metal alkoxide supplied as a white to off-white free-flowing powder or as a clear to pale yellow methanolic solution. Commercial product grades are described by physical state and concentration, such as potassium methoxide solution 32 wt% in methanol or potassium methoxide powder 96% assay; no uniform proprietary model code exists across manufacturers. The compound acts as a strong base and a source of methoxide anion in condensation, alkoxylation, and transesterification reactions. Because it hydrolyses rapidly in contact with water and absorbs carbon dioxide, commercial material is packaged under inert gas and specified by assay, water content, potassium hydroxide content, and potassium carbonate content. The methoxide form avoids the water-forming equilibrium associated with potassium hydroxide dissolution in methanol, which is one of the primary product-selection criteria in water-sensitive processing.
Powder grades are typically specified at ≥ 95.0% w/w potassium methoxide, with residual methanol below 0.5% w/w and free potassium hydroxide limited to ≤ 2.0% w/w. Solution grades are supplied at 25–32 wt% potassium methoxide in methanol, with water controlled below 0.3% w/w. Carbon dioxide absorption during handling raises potassium carbonate content; certificate-of-analysis limits are commonly ≤ 1.0% w/w for solution grade and ≤ 2.0% w/w for powder grade. Particle-size distribution is not standardized across all suppliers but affects powder dissolution time in tank mixing; fine powders dissolve faster but present greater dust exposure and self-heating risk.
Density of a 32 wt% methanolic solution is typically 0.94–0.96 g/cm³ at 20 °C, measured by oscillating U-tube or hydrometer. Flash point is controlled by methanol and falls near 11 °C closed cup, ASTM D93. Water content is determined by ASTM E203 or ISO 760 Karl Fischer titration. The solution is miscible with methanol, ethanol, and some polar aprotic solvents, but reacts with protic media containing significant water or acid. Packaging configurations vary by physical state: solution-grade product is supplied in stainless steel drums, intermediate bulk containers, or bulk stainless steel tanks fitted with nitrogen pads and pressure-relief devices; powder-grade product is supplied in fibre drums with polyethylene liners under nitrogen and is transferred to closed feed hoppers under dry air or nitrogen. Packaging selection is driven by moisture ingress rate and self-heating classification rather than by chemical assay alone.
| Parameter | Powder grade | Solution grade | Test method |
|---|---|---|---|
| Physical appearance | White to off-white free-flowing powder | Clear to pale yellow liquid | Visual inspection |
| Assay as potassium methoxide | 95.0%–99.0% w/w | 25%–32% w/w | Acid-base or potentiometric titration |
| Water content | ≤ 0.5% w/w | ≤ 0.3% w/w | ASTM E203 / ISO 760 |
| Potassium hydroxide | ≤ 2.0% w/w | ≤ 1.5% w/w | Potentiometric titration |
| Potassium carbonate | ≤ 2.0% w/w | ≤ 1.0% w/w | Volumetric titration |
| Methanol content | ≤ 0.5% w/w residual | Balance | Gas chromatography |
Table 1 lists representative commercial acceptance limits; individual lot-specific certificates of analysis supersede the values shown. Published data for specialized high-purity pharmaceutical and electronic-grade specifications is limited, and such quality requirements should be confirmed directly against supplier documentation.
Substitution of potassium methoxide for sodium methoxide is evaluated on methanol solubility, salt-solubility differences, phase-separation behaviour, and residual sodium/potassium limits. In methanol, potassium methoxide is available at 32 wt%, while common sodium methoxide solutions are marketed at 21–30 wt%. The higher solution concentration can reduce transport volume and methanol inventory in continuous dosing. On an equimolar basis, the mass factor relative to sodium methoxide is 1.30 because the molecular weights are 70.13 g/mol and 54.03 g/mol. Both reagents are strong bases; however, potassium salts produced after neutralization have different aqueous solubility and may partition differently in glycerol and aqueous wash streams.
Anhydrous methoxide solutions do not introduce additional water when the alkoxide is dissolved in methanol. Potassium hydroxide, by contrast, participates in the equilibrium KOH + CH3OH ⇌ KOCH3 + H2O, generating water in the methanolic catalyst stream and increasing the risk of soap formation in fatty acid methyl ester production. Potassium methoxide and sodium methoxide are both moisture-sensitive and release methanol under hydrolysis. The choice between sodium and potassium methoxide is frequently determined by product contamination limits for sodium or potassium, post-reaction salt separation, and local raw-material cost. Where residual metal limits are regulated, analytical methods such as USP <233> or EN ISO 11885 are used; potassium methoxide is selected where potassium residues are acceptable and sodium is restricted. Quantitative rate comparisons across all substrate classes are not uniformly established in public literature; published kinetic data for specific configurations is limited, and selection should be confirmed by laboratory trials under plant-specific feed quality and temperature profiles.
| Parameter | Potassium methoxide | Sodium methoxide | Potassium hydroxide |
|---|---|---|---|
| Molecular weight | 70.13 g/mol | 54.03 g/mol | 56.11 g/mol |
| Typical methanolic concentration | 25–32 wt% | 21–30 wt% | Prepared in methanol; equilibrium generates water |
| Water-forming reaction upon methanol dissolution | None from alkoxide form | None from alkoxide form | KOH + CH3OH ⇌ KOCH3 + H2O |
| Typical commercial powder assay | ≥ 95.0% w/w | ≥ 97.0% w/w | 90–95% flake/pellet |
| Flash point of methanolic solution | ≈ 11 °C closed cup | ≈ 11 °C closed cup | Not applicable as solid; methanol solution has similar value |
| Moisture sensitivity | High; hydrolyses to KOH and methanol | High; hydrolyses to NaOH and methanol | High; deliquescent |
Relative to potassium tert-butoxide, potassium methoxide has lower molecular weight and less steric hindrance. In reactions requiring selective enolate formation with hindered alkoxides, potassium tert-butoxide is often selected; in methyl ester formation and transesterification, potassium methoxide provides the required methoxide nucleophile at lower molecular weight per mole. Direct substitution should not be assumed because the two bases have different steric profiles and can give different product distributions in elimination-sensitive substrates. Experimental verification is performed under ASTM or in-house reaction monitoring conditions because published comparative data for specific pharmaceutical substrates is limited.
Transesterification of triglycerides with methanol using potassium methoxide is operated in continuous plants with sealed dosing systems. A 32 wt% potassium methoxide solution is injected into a dry methanol slipstream upstream of static mixers, with catalyst loading adjusted to 0.8–1.0 wt% of oil mass when free fatty acid content is ≤ 0.1 wt% expressed as KOH and water is below 0.05 wt%. Reaction is maintained at 60–65 °C in a continuous stirred-tank reactor or plug-flow configuration with residence time 60–120 min; ester content is monitored by EN 14103, and free and total glycerol by EN 14105 and EN 14106. Under these conditions, glycerol-rich phase separation typically occurs within 30–60 min after reactor discharge. Process conflict arises when free fatty acid content exceeds 1.0 wt%, because soap formation consumes the alkoxide and stabilizes emulsions; pre-esterification or acid esterification is then required before the alkaline transesterification step. Excess methanol is stripped at 80–120 mbar and 80–110 °C; residual soap and catalyst are removed by acidulation and water washing. The finished methyl ester is checked against EN 14214 limits, including ester content ≥ 96.5% m/m, water ≤ 500 mg/kg, and total contamination ≤ 24 mg/kg. Potassium methoxide is preferred where low water introduction is critical because the alkoxide does not release water into the methanolic catalyst stream; potassium hydroxide additions can produce water through methanolate formation and increase soap formation at equivalent free fatty acid levels. Published plant data for this process are available for standard rapeseed and soybean oil feedstocks, but published data for specific configurations such as high-FFA palm fatty acid distillate or supercritical methanol conditions is limited.
Potassium methoxide is classified under CLP Regulation (EC) No 1272/2008 with hazard statements H251 self-heating, H314 skin corrosion, H225 highly flammable liquid and vapour for methanolic solution, and EUH014 reacts violently with water. Storage is maintained in closed, nitrogen-purged vessels at 15–30 °C and away from water, acids, halogenated solvents, and air. Powder handling requires humidity below 60% RH to limit surface hydrolysis and carbon dioxide uptake. Wetted surfaces are stainless steel 316L or high-density polyethylene with PTFE/ETFE gaskets. Dosing pumps for methanolic solutions include magnetically coupled or diaphragm heads with PTFE/ETFE wetted parts; lines are purged with dry nitrogen and protected from moisture ingress. UN 3274 is used for alcoholates solution in alcohol; the solid material is shipped under UN 3206 alkali metal alcoholates, self-heating, corrosive. Water must not be used as an extinguishing agent; dry chemical or alcohol-resistant foam is applied. Exposure to atmospheric moisture in open containers for more than a few minutes reduces assay and raises potassium hydroxide and carbonate content. Copper, zinc, aluminum, and galvanized steel are avoided due to base attack and potential hydrogen generation. Spill containment is sealed and ventilated to prevent methanol vapour accumulation; area monitors set at 10% LEL are standard in storage and dosing rooms.
Fine chemical synthesis uses potassium methoxide as a base catalyst in Claisen condensations, esterifications, epoxide alcoholysis, and preparation of pharmaceutical intermediates. In batch alkoxylation, the powder or solution is added to an alcohol and substrate at 0–30 °C under nitrogen; exothermic heat is removed by jacket cooling, and reaction mass temperature is controlled to limit aldol side reactions. The base is neutralized with carboxylic acid or mineral acid before aqueous workup; potassium salts partition to the aqueous phase. For solvent-free Claisen condensations, ester and methoxide are combined under vacuum at 50–150 mbar absolute and 80–120 °C to remove methanol and shift equilibrium. Because potassium methoxide is less sterically hindered than potassium tert-butoxide, it tends to act as a methyl esterification/transesterification catalyst rather than a hindered elimination base. Equipment includes glass-lined or stainless steel 316L reactors with nitrogen-blanketed addition ports. The operational boundary is water below 0.2% w/w in the reaction mass; above this level, methoxide hydrolysis reduces catalyst activity and increases hydroxide-derived side reactions. Published data for solvent-free synthesis of acetoacetate esters is well documented, while data for less common substrates and mixed-solvent systems is limited.
