| HS Code | 378338 |
| Product Name | Sodium Tert-Butoxide |
| Chemical Formula | C4H9NaO |
| Cas Number | 865-48-5 |
| Molecular Weight | 96.10 g/mol |
| Appearance | White to off-white crystalline powder |
| Melting Point | 180 °C |
| Boiling Point | Decomposes upon heating |
| Density | 0.93 g/cm³ |
| Solubility In Water | Reacts with water |
| Solubility In Organic Solvents | Soluble in tert-butanol and tetrahydrofuran |
| Ph | Strongly alkaline in solution |
| Storage Conditions | Store in a cool, dry, well-ventilated area away from moisture and acids |
| Hazard Classification | Corrosive; causes severe skin burns and eye damage |
| Purity | Typically ≥97% |
| Synonyms | Sodium t-butoxide; Sodium tert-butylate |
As an accredited Sodium Tert-Butoxide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sodium tert-butoxide packaging: sealed, moisture-resistant 100 g amber glass bottles with clear hazard labels, lot numbers, and safe-handling instructions. |
| Container Loading (20′ FCL) | Sodium Tert-Butoxide loaded in a 20′ FCL: palletized, moisture-proof drums, securely braced, labeled corrosive, kept dry, per IMDG. |
| Shipping | Ship Sodium tert-butoxide as UN 3206, Alkali metal alcoholates, self-heating, corrosive, n.o.s., Class 4.2 (subsidiary 8), Packing Group II. Use sealed, moisture-resistant packaging under inert gas, proper labels, and documentation. Protect from water, heat, and ignition sources. Comply with DOT, IMDG, IATA, and local dangerous goods rules. |
| Storage | Store sodium tert-butoxide in a cool, dry, well-ventilated area, under inert gas (nitrogen or argon). Keep containers tightly closed and protected from moisture, water, acids, alcohols, and oxidizing agents because it is hygroscopic, moisture-sensitive, and strongly basic. Store separately from incompatible materials and follow local regulations for corrosive, water-reactive solids. Ensure secondary containment, clear labeling, and appropriate PPE. |
| Shelf Life | Sodium tert-butoxide is moisture-sensitive; stored dry, sealed, under inert gas, it typically remains stable for one to two years. |
During production-scale manufacture of an arylpiperazine advanced intermediate intended for a 21 CFR 211–compliant API supply chain, sodium tert-butoxide functions as the base in palladium-catalyzed C–N bond construction. A glass-lined 1,500 L reactor is used. The aryl chloride is charged at 1.0 equivalent, the secondary amine at 1.1–1.3 equivalents, sodium tert-butoxide at 1.4–1.8 equivalents, tris(dibenzylideneacetone)dipalladium(0) at 0.5–2.0 mol%, and (±)-BINAP at 1.0–4.0 mol%. Toluene is dried to ≤200 ppm water by Karl Fischer titration per ASTM E1064 before charging. The mass is agitated under nitrogen at 80–85°C for 6–12 h. Reaction progress is monitored by HPLC area% using a C18 column and USP <621> methodology. The terminal product after extractive workup is an N-arylated piperazine isolate, crystallized from n-heptane/ethyl acetate to ≥98.5 area% with residual palladium <50 ppm by ICP-OES per USP <233>. Compliance requires tert-butanol and toluene residuals controlled under ICH Q3C; organic volatiles are reduced in a wiped-film evaporator at 45°C and 2 kPa. The extraction sequence uses 10 wt% citric acid at pH 5.5–6.5, followed by activated carbon treatment to lower palladium before isolation. The principal operational boundary is moisture in solvent and headspace: water converts sodium tert-butoxide to sodium hydroxide, leading to aryl chloride hydrolysis and lower amination selectivity.
Electronic-grade hole-transport materials such as N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine are synthesized through double Buchwald–Hartwig coupling of 4,4′-dibromobiphenyl with diphenylamine. Sodium tert-butoxide is used at 2.5–3.0 equivalents relative to the dibromide because two equivalents of hydrobromic acid are neutralized per complete double amination. The amine is charged at 2.2–2.8 equivalents, Pd₂(dba)₃ at 0.5–1.0 mol%, and BINAP at 1.0–2.0 mol%. The reaction mass is kept at 100–110°C in toluene for 12–24 h. Conversion is tracked by GC area% using a DB-5 column. After aqueous sodium chloride washing and carbon treatment, the crude product is filtered through a 0.45 µm PTFE membrane and recrystallized twice from toluene/ethanol. Final purification by vacuum sublimation at 10⁻⁴ Pa and 280–300°C reduces alkali metal content to <10 ppm by ICP-MS. The product must meet RoHS Directive 2011/65/EU Annex II restrictions on lead and cadmium and is used as a hole-transport layer in organic light-emitting diodes. Process limit: excess base above 3.0 equivalents produces measurable dehalogenated byproducts; base below 2.5 equivalents stalls at the mono-aminated intermediate and lowers ultimate purity below 99.5 area%.
| Parameter | Pharmaceutical amination | OLED double amination |
|---|---|---|
| Sodium tert-butoxide equivalents | 1.4–1.8 | 2.5–3.0 |
| Amine equivalents | 1.1–1.3 | 2.2–2.8 |
| Pd precatalyst loading | 0.5–2.0 mol% | 0.5–1.0 mol% |
| Ligand loading | 1.0–4.0 mol% | 1.0–2.0 mol% |
| Reaction temperature | 80–85°C | 100–110°C |
| Target residual Pd | <50 ppm via USP <233> | <10 ppm via ICP-MS |
Across 1,2,4-triazole fungicide intermediate campaigns, sodium tert-butoxide is selected when aqueous sodium hydroxide causes hydrolysis of an acid-labile chloroketone. In a typical 2,000 L glass-lined vessel, 1H-1,2,4-triazole is dissolved in dry DMF at 20–25°C and treated with sodium tert-butoxide at 1.0–1.1 equivalents. The resulting sodium triazolide is cooled to −5 to 0°C, and an α-chloroketone side-chain precursor is added at 0.95–1.0 equivalents over 4–6 h. The reaction is held at 0–5°C for 8 h and quenched into 10 wt% ammonium chloride solution, maintaining pH 6.5–7.5. Extraction with toluene, solvent exchange to methanol, and crystallization give a triazole ketone intermediate with GC purity ≥98.0 area%. DMF and toluene residuals are controlled by vacuum drying at 50°C and 3 kPa. Terminal conversion to a triazole fungicide technical material is conducted in facilities holding EU REACH registration. The acceptable moisture in DMF is ≤150 ppm by Karl Fischer per ASTM E1064; water above this level increases hydrolysis and reduces selectivity to the N-alkylated isomer.
For an α-tert-butoxy-ω-hydroxy poly(ethylene glycol) prepared for monofunctional linker construction, sodium tert-butoxide is the initiating alkoxide in ring-opening polymerization of ethylene oxide. The target number-average molecular weight is set by the molar ratio of monomer to initiator: a 30:1 ethylene oxide-to-sodium tert-butoxide charge gives a theoretical molar mass of approximately 1,396 g/mol. The 500 L stainless steel polymerization vessel is leak-tested, vacuum-dried to ≤20 ppm water by dew-point measurement, and purged with nitrogen. Sodium tert-butoxide is charged as a 1.0 M THF solution, heated to 40–60°C, and ethylene oxide is fed at 0.3 MPa over 6–10 h. After a 2 h digestion, the reaction is quenched with acetic acid and stripped in a thin-film evaporator at 70°C. Hydroxyl number is tested by ASTM D4274-21; the expected range for 1,400 g/mol monol is 38–42 mg KOH/g. Size-exclusion chromatography polydispersity is held below 1.05. Residual ethylene oxide and THF are controlled under ICH Q3C. Operationally, water and carbon dioxide are the critical poisons: >50 ppm moisture in the reactor produces α,ω-dihydroxy PEG and broadens the molecular weight distribution. The purified monol is used as a starting material for heterobifunctional PEG linkers in later antibody-drug conjugate manufacturing.
In a water-excluding THF system, sodium tert-butoxide drives a Claisen condensation yielding a UV-A filter intermediate. 4-methoxyacetophenone is charged at 1.05 equivalents, methyl 4-tert-butylbenzoate at 1.0 equivalent, and sodium tert-butoxide at 1.2–1.5 equivalents in a 1,000 L reactor. The mass is held at 50–60°C for 6–8 h. Reaction completion is monitored by HPLC at 360 nm using a C18 column; methyl ester consumption is confirmed by GC area% on a DB-624 column. The batch is quenched into 5 wt% aqueous citric acid to pH 3.0–4.0, extracted with ethyl acetate, and crystallized from isopropanol. The isolated butyl methoxydibenzoylmethane intermediate is dried at 45°C and 2 kPa to residual solvent limits set under ICH Q3C. For cosmetic ultraviolet filter use, the active ingredient is assessed under FDA 21 CFR 352.10 and is formulated at a maximum concentration of 3% in the United States. The critical process boundary is water: solvent Karl Fischer moisture above 200 ppm hydrolyzes the ester and generates sodium 4-tert-butylbenzoate, depressing isolated yield below 85%.
Retinal and vitamin A intermediate production uses sodium tert-butoxide to generate phosphorus ylides from β-ionylideneethyltriphenylphosphonium salts. The phosphonium salt is suspended in anhydrous THF at −20 to 0°C and treated with sodium tert-butoxide at 1.05–1.2 equivalents. The ylide solution is aged for 30–60 min, and a C₁₀ aldehyde electrophile is added at 0.95–1.0 equivalents over 2–4 h. The reaction is maintained at 0–10°C for 8–12 h. Workup includes aqueous sodium bisulfite washing, phase separation, and solvent exchange to heptane. The resulting retinoid intermediate is isolated by crystallization and assayed by HPLC at 370 nm using a C30 column. Residual triphenylphosphine oxide is controlled below 0.5 wt% by 31P NMR or HPLC-ELSD. Compliance follows ICH Q3C for THF and heptane residuals. The terminal product is used in vitamin A acetate or retinol synthesis after hydrogenation and acetylation. The critical parameter is base quantity: sodium tert-butoxide below 1.05 equivalents leaves unreacted phosphonium salt, while charge above 1.2 equivalents promotes epimerization of the retinoid side chain and reduces all-trans content below compendial limit.
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Commercial sodium tert-butoxide is supplied in two primary forms: an anhydrous powder grade with nominal total base assay of 98.0–99.0% and a solution grade in tetrahydrofuran with nominal concentration of 1.0–2.0 M. The powder is a white to off-white solid with a bulk density between 0.40 g cm−3 and 0.60 g cm−3; it is packaged under nitrogen in polyethylene-lined HDPE drums and re-sealed under inert gas after sampling. The product is used as a sterically hindered, non-nucleophilic base for enolate formation, dehydrohalogenation, and phosphonium ylide generation. Model designations in commercial literature distinguish standard grade with moisture ≤ 1.0% and low-moisture grade with moisture ≤ 0.5%. The low-moisture designation is specified when downstream electrophiles are sensitive to sodium hydroxide generated by hydrolysis. The CAS registry number is 865-48-5 and the molecular weight is 96.10 g mol−1.
The sodium cation provides a lower molecular weight per mole of base (96.10 g mol−1) than potassium tert-butoxide (112.21 g mol−1) and a more compact ion pair in low-polarity media. Potassium tert-butoxide generally exhibits higher solubility in tetrahydrofuran and faster deprotonation kinetics, but the sodium analog is selected when controlled reaction of weakly acidic substrates is required and when residual potassium must be minimized in pharmaceutical intermediates. Sodium methoxide, by contrast, is a smaller alkoxide with molecular weight 54.02 g mol−1 and is commonly used in transesterification and nucleophilic substitution. The tert-butoxide ligand suppresses O-alkylation and favors E2 elimination or kinetic enolate generation at low temperature.
In tetrahydrofuran, sodium tert-butoxide is aggregated and the effective solution state depends on residual tert-butanol. The presence of tert-butanol at 0.5–2.0 wt% can increase apparent solubility but reduces deprotonation efficiency by hydrogen bonding to the alkoxide. For kinetic enolate formation, residual alcohol is kept below 0.5 wt% by using powder dried under vacuum at 40°C for 12 h or by azeotropic removal with THF. This drying step is standard in research laboratories and pilot plants before use with highly moisture-sensitive substrates. In dimethyl sulfoxide, deprotonation of substrates with pKa up to approximately 30 is possible, whereas in tetrahydrofuran the practical substrate acidity window is narrower because the enolate can aggregate and precipitate.
| Comparative parameter | Sodium tert-butoxide | Potassium tert-butoxide | Sodium methoxide |
|---|---|---|---|
| Molecular weight | 96.10 g mol−1 | 112.21 g mol−1 | 54.02 g mol−1 |
| Typical anhydrous assay | 98.0–99.0% | 97.0–99.0% | 95.0–99.0%; methanol solution grades common |
| Steric bulk | High | High | Low |
| Primary reaction mode | Deprotonation, E2 elimination | Deprotonation, elimination, stronger base | Nucleophilic substitution, transesterification |
| Solubility in THF | Moderate; solution grade 1.0–2.0 M | Higher; solution grade commonly 1.0–2.0 M in THF | Low; methanol is preferred |
Published data for exact solubility limits vary with temperature, residual alcohol content, and the presence of lithium or sodium halides.
For anhydrous powder grades, the release certificate typically reports total base assay by acid-base titration after hydrolysis at ≥ 98.0%, sodium hydroxide at ≤ 0.8%, sodium carbonate at ≤ 0.3%, moisture by Karl Fischer at ≤ 0.5%, and chloride at ≤ 0.2%. Trace-metal limits for polymerization-grade material are commonly set at Fe ≤ 10 mg kg−1, Ni ≤ 5 mg kg−1, and Cu ≤ 5 mg kg−1, measured by ICP-OES after nitric acid digestion. Moisture determination is performed by coulometric Karl Fischer titration after dispersion in dry methanol, aligned with ASTM E203. Quality systems for commercial supply are maintained under ISO 9001:2015, and safety data sheets are issued in accordance with CLP Regulation (EC) No 1272/2008.
| Parameter | Anhydrous powder grade | Low-moisture powder grade | THF solution grade |
|---|---|---|---|
| Total base assay | ≥ 98.0% | ≥ 98.5% | 1.0–2.0 M nominal |
| Moisture | ≤ 1.0% | ≤ 0.5% | ≤ 0.3% as water in solution |
| Sodium hydroxide | ≤ 0.8% | ≤ 0.4% | ≤ 0.2% relative to total base |
| Bulk density | 0.40–0.60 g cm−3 | 0.45–0.60 g cm−3 | Not applicable |
| Packaging atmosphere | Nitrogen | Argon or nitrogen | Nitrogen, sealed stainless steel or glass |
Chloride is determined by potentiometric titration using silver nitrate with a silver billet electrode, and sodium hydroxide is determined by acid-base titration after reaction with barium chloride to precipitate carbonate. Particle-size distribution is measured by laser diffraction using a dry dispersion cell at 0.5–1.0 bar; typical D50 is 120–250 µm, with D90 below 400 µm. Drums are typically 50 L or 200 L HDPE with polyethylene liners and an internal atmosphere of nitrogen. Headspace oxygen should be below 5 vol% and headspace moisture below 100 ppmv at the time of sealing. After opening, the drum must be resealed under nitrogen, and the remaining material should be consumed within 4–6 weeks if stored at 15–25°C.
Open exposure to air at relative humidity above 60% increases surface moisture and free sodium hydroxide content. In a warehouse or production suite, the powder should be transferred in a nitrogen-purged glovebox or through split-valve contained systems; transfer lines should have a dew point no higher than −40°C. Grounded stainless-steel or Hastelloy C-22 equipment with PTFE gaskets is used to avoid static discharge and corrosion. Sodium tert-butoxide is classified as a flammable solid and skin corrosive under CLP; no water-based fire suppression should be used because water reacts exothermically.
Multi-step pharmaceutical intermediate synthesis frequently specifies sodium tert-butoxide for the deprotonation of ketones, phosphonates, and weakly acidic heterocycles. In a 100–500 L glass-lined reactor, the solid is charged through a nitrogen-purged lance while the substrate is held at 0–5°C in THF; the base is added at a rate that limits the exotherm to 5–10°C per 15 min. The resulting enolate is then aged at −20°C to −10°C for 30–60 min before addition of the electrophile. If free sodium hydroxide exceeds 0.5%, hydrolysis of moisture-sensitive electrophiles can raise the related-substance profile above 0.10%; low-moisture grade is therefore written into the bill of materials for these stages. Process analytical technology using in-situ FTIR or Raman probes tracks the disappearance of the carbonyl stretch at approximately 1710 cm−1 and the growth of enolate absorption, allowing the base charge to be stopped at 1.02–1.05 equivalents rather than using a large excess. Published data for specific impurity outcomes vary with substrate concentration and water content, so laboratory verification under the intended solvent ratio is performed before scale-up.
Residual sodium removal can be performed by aqueous citric acid quench at 10–20°C, followed by phase separation. The aqueous phase is extracted twice with THF or methyl tert-butyl ether; combined organic layers are washed with 15–20 wt% sodium chloride solution to reduce water carryover. The product solution is then filtered through a cartridge filter with 0.45 µm retention to remove insoluble sodium salts before distillation.
When phosphonium salts are deprotonated to ylides in THF or toluene, sodium tert-butoxide is added at 1.0–1.2 equivalents relative to the salt. The reaction is usually conducted between −20°C and 25°C for stabilized ylides; semi-stabilized ylides may require warming to 40°C for complete conversion. The hindered alkoxide minimizes nucleophilic attack at the phosphonium center, which is a common side reaction with less hindered bases. For E2 dehydrohalogenation of secondary or tertiary alkyl halides, the anti-periplanar requirement and steric bulk favor the less substituted alkene, often with selectivity above 80:20 when the substrate has accessible β-hydrogens. Buchwald-Hartwig amination employs sodium tert-butoxide to deprotonate the amine and activate the palladium catalyst; catalyst loadings of 0.5–2.0 mol% Pd with 1.0–1.5 equivalents of base are typical. In toluene, the sodium alkoxide may remain partly heterogeneous, so THF or 1,4-dioxane is often used to maintain a homogeneous reaction mixture.
With palladium catalysts such as Pd₂(dba)₃/XPhos, the base is added after the catalyst and ligand have been stirred under inert atmosphere; the sequence avoids catalyst deactivation by excess amine and prevents formation of inactive palladium hydroxide species. For substrates with acidic α-protons, base strength and temperature must be balanced to avoid aldol condensation. Addition of the ketone to the base at −30°C rather than inverse addition usually improves enolate selectivity and reduces the homoketone by-product below 1% area by GC-FID. When sodium tert-butoxide is compared with sodium hydride in the same deprotonation, sodium tert-butoxide does not generate hydrogen gas and therefore simplifies vent sizing and electrical area classification. Conversion is monitored by gas chromatography with flame ionization detection after quench with saturated ammonium chloride; the alkene ratio is calculated by area normalization and confirmed by GC-MS for branched and linear isomers.
At temperatures above 150°C, sodium tert-butoxide begins to decompose by β-hydride elimination from the alkoxide ligand, yielding isobutylene, sodium hydroxide, and sodium carbonate or sodium oxide depending on atmosphere. The decomposition onset is shifted lower when the powder has absorbed moisture; therefore drying and storage below 25°C and 30% RH are specified for long-term stability. Thermogravimetric analysis under nitrogen at a heating rate of 10 K min−1 typically shows principal decomposition between 180°C and 300°C; published data for this specific configuration is limited and varies with heating rate and sample morphology. Differential scanning calorimetry of the dry powder usually shows no sharp melting endotherm before decomposition; the material is an amorphous or microcrystalline solid. These thermal limits require that solvent removal from reaction mixtures be conducted under vacuum at jacket temperatures no higher than 45–55°C when sodium tert-butoxide-derived salts are still present.
Solubility in THF is limited; at 25°C, saturated solutions are typically below 2.0 M, and the powder can form a thick paste if solids loading exceeds 15 wt%. High-torque overhead agitation with an anchor or helical ribbon impeller is used to maintain suspension in large vessels. The reaction mass often thickens after enolate formation; a variable-frequency drive motor with torque overload protection prevents stall in 100 L and larger reactors. Incompatibility with chlorinated solvents is a critical boundary: contact with chloroform or dichloromethane under basic conditions may generate dichlorocarbene and produce an exotherm, so these solvents are avoided unless deliberately controlled for cyclopropanation or carbene addition.
Open exposure to air at 50% RH increases the moisture content of an anhydrous powder sample from 0.4 wt% to 0.8 wt% within 30 min, as determined by Karl Fischer titration. This sensitivity is the primary reason that production-scale handling uses pressure-rated nitrogen purges, rapid-transfer ports, and resealable split-valve containers. For waste quench, the alkoxide is slowly added to cooled aqueous ammonium chloride or dilute acetic acid under agitation; direct addition of water to solid sodium tert-butoxide should be avoided because the heat of hydrolysis can cause localized boiling. Quench temperature is maintained below 25°C to limit volatile organic release and foam formation. Aqueous quench tanks are vented through knock-out pots to prevent carryover of tert-butanol and isobutylene into facility drains. The powder is incompatible with strong acids, oxidizing agents, and concentrated peroxides; separate storage from these materials is required under the segregation logic of the site’s chemical warehouse.
