| HS Code | 995677 |
| Product Name | Lithium tert-Butoxide |
| Iupac Name | Lithium 2-methylpropan-2-olate |
| Synonyms | LiOtBu; tert-Butoxylithium; Lithium tert-butanolate |
| Cas Number | 1907-33-1 |
| Ec Number | 217-586-0 |
| Molecular Formula | C4H9LiO |
| Molecular Weight | 80.06 g/mol |
| Appearance | White to off-white powder or crystalline solid |
| Physical State At 20c | Solid |
| Melting Point | 280 °C (decomposes) |
| Boiling Point | Decomposes before boiling |
| Density | 0.885 g/mL at 25 °C (1.0 M solution in THF) |
| Solubility | Soluble in tetrahydrofuran, ethers, and hydrocarbons; reacts with water and alcohols |
| Acidity | Strong base; conjugate acid is tert-butanol |
| Reactivity | Reacts with water, acids, alcohols, and oxidizing agents |
| Incompatibilities | Water, acids, alcohols, oxidizers |
| Storage Conditions | Store dry under inert gas; protect from moisture and air |
| Hazard Classification | Corrosive; moisture-sensitive; may be flammable as solution |
As an accredited Lithium Tert-Butoxide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 g of Lithium Tert-Butoxide powder in a sealed, nitrogen-purged amber glass bottle with a PTFE-lined cap. |
| Container Loading (20′ FCL) | 20′ FCL loading: Lithium tert-butoxide in sealed drums on pallets, dry container, secured, labeled, compliant with hazardous materials regulations. |
| Shipping | Solid lithium tert-butoxide ships as UN 3263, Corrosive solid, basic, organic, n.o.s. (Lithium tert-butoxide), Class 8, Packing Group II. Solution forms may ship as UN 2924, Flammable liquid, corrosive, n.o.s., Class 3(8). Use UN-approved, airtight, moisture-proof packaging with appropriate hazard labels. |
| Storage | Store Lithium tert-Butoxide in a cool, dry, well-ventilated, fire-resistant area away from water, acids, oxidizers, and ignition sources. Keep containers tightly closed under inert gas (argon or nitrogen) because it is moisture- and air-sensitive. Avoid dust formation; ground containers. Use flammable-solids storage, segregate incompatible materials, protect from static electricity and physical damage, and consult the SDS. |
| Shelf Life | Lithium tert-butoxide shelf life: about two years when stored dry, sealed, under inert gas; moisture and air degrade it. |
Lithium tert-butoxide functions as a sterically hindered, non-nucleophilic base in anhydrous aprotic media, selected where potassium tert-butoxide produces unacceptable dehydrohalogenation selectivity or where sodium hydride heterogeneity slows reaction progress. In registered intermediate synthesis, the reagent is charged at 0.95–1.40 molar equivalents relative to the most acidic proton; most processes converge at 1.05–1.20 equivalents to maintain conversion above 90% while limiting residual alkoxide and lithium carryover into subsequent phase splits. The addition is conducted in glass-lined or Hastelloy C22 vessels under nitrogen protection, with jacket temperature spanning -20 °C to 25 °C and an addition half-life not shorter than 30 min for batch sizes above 1000 L. Production-scale equipment data indicate that local overshoot beyond 35 °C during THF or 2-methyltetrahydrofuran bulk additions triggers solvent reflux and raises the impurity profile before quench. After age-out, the reaction mass is transferred into an aqueous ammonium chloride or orthophosphate buffer at 0–10 °C for reverse quench; the organic layer is washed to conductivity below 50 µS/cm, concentrated, and crystallized from heptane or ethyl acetate. Terminal products are late-stage registered intermediates, crystalline free bases, and final small-molecule APIs. Compliance obligations include ICH Q7 for GMP manufacture from the point of registered intermediate introduction, USP <467> for residual solvent control, ICH Q3D for elemental impurities, and pharmacopoeial monographs for final API release. Published data for LiOtBu-specific residual lithium thresholds in final API are limited; method validation using ICP-MS and a lithium-specific limit in the release specification must be justified under ICH Q3D risk assessment. Incompatibilities include acid-sensitive protecting groups, nitroarenes, and chlorinated solvents capable of participating in elimination.
In anionic ring-opening polymerization of ethylene oxide and propylene oxide, lithium tert-butoxide serves as an alkali metal alkoxide initiator whose lithium counterion suppresses chain transfer to protic impurities, provided reactor water content remains below 10 ppm and monomer water below 20 ppm. The molar ratio of epoxide monomer to initiator is set between 20:1 and 500:1 to control number-average molecular weight within 350–5000 g/mol for pharmaceutical-grade monomethoxy polyethylene glycol and 400–2000 g/mol for urethane-grade polyether diols. Polymerization is carried out in jacketed stainless steel or glass-lined loop reactors at 80–120 °C under 0.3–0.6 MPa nitrogen; ethylene oxide is metered through mass flow-controlled valves because the exotherm demands removal of approximately 94 kJ/mol of ethylene oxide ring strain and addition heat. Vessels are equipped with rupture disks and dedicated quench headers; the lithium alkoxide is charged as a solution in tetrahydrofuran or as a preformed alkoxide salt to avoid localized autoacceleration. After monomer feed-out and digestion, residual alkoxide is neutralized with acetic acid or carbon dioxide, and the crude polyether is stripped under vacuum at 90–110 °C. Terminal product types include monomethoxy PEGs for peptide PEGylation, polyether diols for thermoplastic polyurethanes, and PEG-based hydrogels. Compliance standards include ASTM D4274-21 for hydroxyl number, USP Polyethylene Glycol monograph for pharmaceutical grades, ICH Q3D for lithium and heavy metal control, and ISO 10993-1:2018 when the polyether is intended for medical device contact. Published propagation rate coefficient data for LiOtBu-specific systems remain scarcer than for potassium tert-butoxide; therefore, pilot-scale molecular weight calibration should precede fixed recipe transfer.
Sulfonylation and carbamoylation of heterocyclic amines in crop protection intermediate synthesis require a non-nucleophilic base that does not accelerate ring-opening of five-membered heterocycles. Lithium tert-butoxide is employed for this purpose at 1.0–1.3 molar equivalents relative to the nucleophile; below 1.0 equivalent conversion stalls, while above 1.3 equivalents ring-opening or sulfone elimination side products increase. Production batches are run in glass-lined or PTFE-lined equipment under nitrogen, with solvent choices limited to THF, 2-methyltetrahydrofuran, or dimethylacetamide; the reaction temperature is controlled between -10 °C and 30 °C because exothermic sulfonylation can otherwise exceed 45 °C and degrade thermally labile intermediates. After reaction completion, the batch is quenched into dilute hydrochloric acid or acetate buffer, extracted, and the crude oil is crystallized or distilled. Terminal product types are technical-grade intermediates for azole and pyrazole crop protection active ingredients. Compliance requirements include Regulation (EC) No 1107/2009 for active substance approval in the EU, REACH registration for lithium tert-butoxide, EPA 40 CFR Part 158 data requirements for registration in the United States, and FAO specifications where end-use concentrates enter public health or export channels. Published data for LiOtBu-specific impurity kinetics in proprietary agrochemical routes are limited; before scale-up, intermediate purity must be characterized by HPLC or UPLC with mass confirmation against a reference impurity bank. Avoid combination with chlorinated process solvents due to competitive dehydrohalogenation.
Vapour delivery of lithium tert-butoxide in atomic layer deposition chambers remains sensitive to source temperature and carrier gas balance because the precursor is solid at room temperature and has a narrow evaporation window before thermal decomposition becomes measurable. The source vessel is held at 130–160 °C; argon carrier flow is set at 10–50 sccm through heated lines maintained at 160–180 °C. The deposition chamber operates at 225–350 °C substrate temperature and 1–3 Torr base pressure. Typical pulse parameters are: lithium tert-butoxide 0.2–2.0 s, inert purge 5–20 s, oxygen plasma or ozone oxidant 0.5–3.0 s, with cycle counts of 500–3000 depending on target film thickness. The downstream production process includes precursor loading under nitrogen in ISO 14644-1:2015 Class 5 cleanroom conditions, in-situ quartz crystal microbalance calibration, and post-deposition annealing at 300–600 °C for crystalline phase stabilization. Terminal product types include lithium niobate thin films for electro-optic waveguides, lithium lanthanum titanium oxide solid-electrolyte interlayers, and lithium phosphate/oxide cathode coatings. Compliance standards include SEMI F21-1302 for contamination control, ISO 14644-1:2015 for cleanroom particulate classification, and IEC 62133-2:2017 for final cell safety if the films enter commercial lithium batteries. Table 1 below lists delivery window boundaries observed in cross-flow ALD equipment. Published data for long-term source stability above 180 °C are limited; film-level SIMS lithium profiling is required to confirm thickness uniformity before device qualification.
| Parameter | Lower limit | Upper limit |
|---|---|---|
| Source vessel temperature (°C) | 130 | 160 |
| Heated line temperature (°C) | 160 | 180 |
| Substrate temperature (°C) | 225 | 350 |
| Base pressure (Torr) | 1 | 3 |
| LiOtBu pulse time (s) | 0.2 | 2.0 |
| Purge time (s) | 5 | 20 |
| Oxidant pulse time (s) | 0.5 | 3.0 |
Hydrolytically sensitive lithium alkoxide precursors are required in sol-gel synthesis of garnet-type lithium lanthanum zirconium oxide where acetate or nitrate salts leave undesirable counterion residues. Lithium tert-butoxide is added at 10–20 mol% excess lithium relative to the nominal Li7La3Zr2O12 stoichiometry to offset lithium oxide volatility during calcination; the precise excess is adjusted by thermogravimetric analysis of the dried gel and confirmed by inductively coupled plasma optical emission spectrometry after sintering. Downstream production involves dissolving lithium tert-butoxide in anhydrous isopropanol or 2-methoxyethanol, mixing with lanthanum and zirconium alkoxides under argon, controlled hydrolysis with water at 0.5–1.5 equivalents, drying at 120–180 °C, calcination in closed alumina crucibles at 700–900 °C with ramp rates not exceeding 2 °C/min, planetary ball milling in yttria-stabilized zirconia media at 300–500 rpm for 4–12 h, and final sintering at 1100–1200 °C in mother powder. Terminal products are sintered LLZO ceramic pellets, free-standing tape-cast electrolyte sheets, and composite cathode electrolyte slurries for solid-state battery fabrication. Compliance standards include IEC 62619:2022 for industrial lithium battery safety, ISO 9001 for process controls, REACH for lithium alkoxide handling, and ISO 14644-1:2015 if powder processing occurs in dry rooms with dew point below -40 °C. Published data for LiOtBu-specific hydrolysis rates in lanthanum-zirconium alcoholic systems are limited; batch-to-batch variance in gel microstructure must be tracked with nitrogen physisorption and particle size analysis before sintering.
Ring-opening polymerization of ε-caprolactone, lactide, and glycolide under lithium counterion control yields resorbable polyesters when high end-group fidelity is required. The monomer-to-initiator ratio is set between 100:1 and 1000:1, producing number-average molecular weights from 10 000 g/mol to 120 000 g/mol; lower ratios increase lithium-alkoxide end group concentration and reduce thermal stability during melt processing. Bulk polymerization is carried out in glass-lined or stainless steel reactors at 120–160 °C under vacuum 0.01–0.1 MPa; for lactide-rich copolymers, solution polymerization in toluene at 80–110 °C is preferred to limit transesterification broadening. After conversion exceeds 95%, the lithium residue is quenched with acetic acid and the polymer is precipitated into cold methanol or heptane, filtered, and vacuum-dried at 40–60 °C. Terminal product types include polycaprolactone microparticles for long-acting injectables, PLGA copolymers for absorbable sutures, and surgical tissue scaffold filaments. Compliance standards include ISO 10993-1:2018 for biological evaluation, ICH Q3C for residual solvent classes, ICH Q3D for lithium and heavy metal control, and ISO 11607-1:2019 for terminally sterilized medical device packaging. Published data for LiOtBu-initiated ε-caprolactone propagation kinetics in bulk are available, but transesterification rate constants vary significantly with reactor surface-to-volume ratio; trial runs in the intended vessel geometry are required.
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Lithium tert-butoxide, CAS 1907-33-1, formula LiOC(CH3)3, molecular weight 80.05 g mol⁻¹, is supplied as a white to off-white free-flowing powder, as a granular solid for controlled solids dosing, and as a 1.0 M solution in tetrahydrofuran. The compound is an oxygen-centred base comprising a sterically hindered tert-butoxy anion and a small lithium cation. The lithium counterion produces a tighter Li–O ion pair than sodium or potassium analogues, and this electronic structure governs solubility, aggregation state, and deprotonation kinetics. The solid reacts exothermically with water to generate lithium hydroxide and tert-butanol, and it must be handled under dry nitrogen or argon. Ambient moisture above 60% relative humidity produces surface caking, localised heat generation, and assay drift toward lithium hydroxide and lithium carbonate; the resulting insoluble haze appears when the material is subsequently dissolved in anhydrous tetrahydrofuran.
Commercial control ranges are commonly reported as assay by non-aqueous acid-base titration, expressed as LiOC(CH3)3, between 97.0% and 99.5%. The mass balance outside the assay is dominated by lithium hydroxide, lithium carbonate, and residual tert-butanol. The lithium hydroxide equivalent is normally limited to ≤1.5% for the 97% grade and is not interchangeable with free water because water is consumed chemically by the alkoxide. In moisture-sensitive downstream chemistry, even 0.5–1.0% assay drift changes the effective base charge and increases the concentration of poorly soluble lithium hydroxide fines, which can blind filters and alter reaction stoichiometry. The REACH-registered safety data sheet requires storage at 2–8 °C under dry nitrogen or argon. Bulk packaging is normally glass or HDPE with fluoropolymer-lined closures, and repeated sampling without inert-gas overpressure is a common source of batch-to-batch hydrolysis in pilot plants. For continuous solids discharge, the transfer line dew point is maintained at or below -40 °C to prevent hydrate formation and crusting at rotary valve seals.
| Parameter | Typical commercial specification | Control basis |
|---|---|---|
| Appearance | White to off-white free-flowing powder or granular solid | Visual inspection |
| Assay as LiOC(CH3)3 | 97.0–99.5% | Non-aqueous acid-base titration |
| Lithium hydroxide equivalent | ≤1.5% depending on grade | Acid-base titration after hydrolysis |
| Residual tert-butanol | Not stated on standard certificates; controlled by vacuum drying | Headspace gas chromatography |
| Storage condition | 2–8 °C under dry nitrogen or argon | Supplier SDS / REACH registration |
Analytical infrared spectra of partially hydrolysed lithium tert-butoxide show a carbonate band near 1450 cm⁻¹ that is distinguishable from the broad lithium hydroxide hydroxyl envelope. Quantification by FTIR is not a substitute for acid-base titration but is used as a rapid incoming-material check in production suites. Karl Fischer titration for water is unsuitable for the neat solid because the alkoxide consumes the titrant; instead, water is inferred from total hydroxide and carbonate after controlled hydrolysis.
The lithium cation radius is approximately 76 pm; sodium and potassium cations are 102 pm and 138 pm, respectively. The smaller radius gives lithium the highest charge density among the three common alkali-metal alkoxides. In ethereal solvents this leads to solvated oligomers rather than a uniform solution of free tert-butoxy ions. A 1.0 M solution in tetrahydrofuran is best described as an equilibrium mixture of contact ion pairs and higher aggregates whose average nuclearity changes with temperature and concentration. When chelating additives such as N,N,N′,N′-tetramethylethylenediamine are present, the aggregate structure is disrupted and the effective basicity increases. In hydrocarbon solvents the aggregation is so extensive that the lithium salt has low practical solubility unless a polar co-solvent or crown ether is introduced.
The consequence for deprotonation is that lithium tert-butoxide is kinetically less aggressive than potassium tert-butoxide in tetrahydrofuran and substantially less aggressive in toluene or hexane. The difference arises not from a weaker alkoxide anion but from the dissociation energy required to release a reactive free or solvent-separated ion pair. In polar aprotic solvents the solvent can separate the ions more effectively, and the conjugate base strength of the hindered alkoxide is more fully expressed. Any reported basicity value that omits solvent and aggregation state is therefore incomplete. This is a central distinction between lithium tert-butoxide and stronger lithium amide bases such as lithium diisopropylamide: the amide base is a stronger carbon acid deprotonator in tetrahydrofuran, but it can add to substrates or require lower temperatures to control side reactions.
For a reactor engineer, the aggregation difference appears as heat evolution on dilution. The dissolution of lithium tert-butoxide in tetrahydrofuran is more exothermic than the dissolution of the sodium salt, and charging the solid into unstirred solvent can create local hot spots that degrade the alkoxide or the solvent. Cooling jackets and controlled addition are specified for solution preparation at scale; the feed must be added to pre-cooled THF at 0–5 °C and stirred under nitrogen until the solution clears.
In a process environment where the base is used as a stoichiometric deprotonating agent, the lithium salt is charged as a THF solution through a mass-flow-controlled metering pump into a jacketed stainless steel reactor with a nitrogen overlay of 0.5 bar gauge. The pump head and feed line are flushed with anhydrous THF after each transfer because stagnant alkoxide solution forms a crust at mechanical seals and check valves. When the solid is delivered from drums, a split-valve transfer system into a nitrogen-purged glovebox or loss-in-weight feeder is used. Open handling without inert atmosphere produces a visible surface crust within minutes; the resulting lumps do not meter uniformly and can blind 10 µm cartridge filters downstream.
The steric bulk of the tert-butoxy ligand suppresses nucleophilic attack at carbonyl, epoxide, and primary alkyl halide centres while retaining base strength to abstract weakly acidic protons from ketones, esters, amides, and sulfones. Lithium tert-butoxide is therefore selected in enolate formation when hydroxide, methoxide, or primary alkoxides would give unacceptable hydrolysis or nucleophilic addition. In Claisen condensations and related ester enolate processes, the lithium counterion influences the geometry and aggregation of the enolate. A change from lithium to sodium or potassium cannot be considered a neutral solvent substitution because the counterion changes both the rate of enolate formation and the diastereoselectivity of subsequent carbon–carbon bond formation.
In anionic ring-opening polymerisation of ethylene oxide or propylene oxide, lithium tert-butoxide acts as an initiator and produces polyether chains with a tert-butyl ether head group. The lithium counterion slows propagation relative to potassium or caesium because the lithium alkoxide chain end remains associated, which can narrow the molar mass distribution when the reactor is operated at 40–60 °C in anhydrous THF. Monomer and solvent must be dried to below 5 ppm water because residual water terminates initiator and generates lithium hydroxide, which broadens the molar mass distribution and accelerates chain transfer to solvent. Published data for this specific lithium alkoxide configuration is limited, so lab-scale initiator efficiency studies are required before scaling to a 100 L stainless steel reactor.
The lithium salt can be evaluated in base-mediated cross-coupling protocols, although sodium and potassium tert-butoxide are more commonly reported for palladium-catalysed C–N and C–O bond-forming reactions. When the substrate contains a sensitive ester or nitrile group that is vulnerable to alkoxide exchange, lithium tert-butoxide may be assessed because the tighter lithium counterion reduces free alkoxide activity. Published data for this specific configuration is limited, and the selection must be validated against the standard potassium tert-butoxide protocol rather than assumed to be equivalent.
Residual solvent control in pharmaceutical applications is governed by ICH Q3C for tetrahydrofuran and tert-butanol, and the use of lithium tert-butoxide in active pharmaceutical ingredient synthesis requires demonstration that lithium is removed to the permitted concentration limits in subsequent crystallisation and aqueous workup.
Lithium tert-butoxide is not a direct substitute for n-butyllithium or lithium diisopropylamide. n-Butyllithium is a carbon-centred nucleophile and a much stronger base, capable of deprotonating terminal alkynes, weakly acidic hydrocarbons, and many aromatic protons. It also adds rapidly to carbonyl groups and can be pyrophoric in concentrated solution. Lithium tert-butoxide abstracts only more acidic protons and typically does not add to unactivated carbonyl groups at the same rate; this non-nucleophilic character is useful when the substrate contains an electrophilic centre that would be consumed by an organolithium reagent. The operational boundary is defined by the pKa of the substrate in the selected solvent: substrates deprotonated by lithium diisopropylamide at low temperature may require higher temperature or a stronger base if lithium tert-butoxide is used.
Lithium diisopropylamide and lithium hexamethyldisilazide are nitrogen-centred lithium amide bases with greater kinetic basicity in ethereal solvents. Lithium tert-butoxide is an oxygen-centred base and is generally weaker in carbon acid deprotonation. It is selected when the stronger amide base would cause over-alkylation, amide addition, or decomposition of a sensitive functional group. The difference is also reflected in byproduct removal: lithium amide reactions release dialkylamine or hexamethyldisilazane, whereas lithium tert-butoxide hydrolyses to tert-butanol and lithium hydroxide.
Sodium tert-butoxide, CAS 865-48-5, and potassium tert-butoxide, CAS 865-47-4, share the same tert-butoxy anion but differ in counterion radius, ion-pair tightness, and aggregate structure. Potassium tert-butoxide is the most aggressive kinetic base of the three in common ethereal solvents because the large potassium cation interacts weakly with oxygen and leaves the alkoxide anion more available for proton abstraction. Sodium tert-butoxide is intermediate. Lithium tert-butoxide is the least kinetically aggressive in tetrahydrofuran and is more sensitive to moisture and carbon dioxide, which convert surface material to lithium hydroxide and lithium carbonate. Its role is not to maximise base strength but to provide a harder, more chelating counterion for enolate geometry control, slower anionic propagation, or a different salt-removal profile.
| Property | Lithium tert-butoxide | Sodium tert-butoxide | Potassium tert-butoxide |
|---|---|---|---|
| CAS | 1907-33-1 | 865-48-5 | 865-47-4 |
| Cation radius | 76 pm | 102 pm | 138 pm |
| Common commercial form | 1.0 M in THF; solid | 1.0 M in THF; solid | 1.0 M in THF; solid |
| Relative kinetic basicity in THF | Lowest | Intermediate | Highest |
| Aggregation tendency | Strong | Moderate | Weak |
| Moisture sensitivity | High | Moderate | High |
| Typical selection driver | Enolate geometry control; epoxide initiation | General alkoxide base | Elimination and cross-coupling |
Direct substitution of lithium tert-butoxide for potassium tert-butoxide in a process optimised for the potassium salt is rarely equivalent. A reaction specifying 1.1 equivalents of potassium tert-butoxide may show incomplete conversion with lithium tert-butoxide in toluene or tert-butanol because of aggregation and slower proton transfer. Conversely, the lithium salt can improve selectivity when the potassium enolate is too nucleophilic or when potassium-containing byproducts are difficult to remove by extraction. The downstream filtration train must also be reviewed because lithium hydroxide and lithium carbonate fines settle and blind filters differently from the corresponding potassium solids.
For electronic-grade or moisture-sensitive applications, incoming lithium tert-butoxide is subjected to an acid-base assay, FTIR for carbonate, and an inductively coupled plasma mass spectrometry screen for transition-metal impurities. The lithium impurity profile is specific to the production route and must be established for each supplier; a change in supplier without re-qualification can introduce silicon, iron, or aluminium residues that are not visible in the assay but are detectable in subsequent thin-film or catalytic applications. The material is not suitable for environments where free water is unavoidable, and any process that requires an aqueous quench must be engineered for controlled hydrolysis and heat removal.
