1,2-EPOXYBUTANE

1,2-Epoxybutane is a reactive epoxide used as a versatile intermediate in organic synthesis.
1,2-Epoxybutane readily undergoes ring-opening reactions with alcohols, amines and other nucleophiles.
Polyethers, specialty chemicals and functional additives can be produced using 1,2-Epoxybutane.

CAS Number: 106-88-7
EC Number: 203-438-2
Molecular Formula: C₄H₈O
Molecular Weight: 72.11 g/mol

Synonyms: 2-Ethyloxirane, 1,2-Butylene oxide, Ethyloxirane, 1,2-Butene oxide, 1,2-Epoxy-butane, Butylene oxide, Ethyl ethylene oxide, Ethyleneoxide homolog, 1-Butene oxide, n-Butylene oxide, RTECS EK3675000, UNII FR67H5388O, ChemSpider 7546, PubChem CID 7834, EINECS 203-438-2, CAS 106-88-7

1,2-Epoxybutane has the molecular formula C₄H₈O and a molar mass of approximately 72.11 g/mol.
The structure of 1,2-Epoxybutane contains a three-membered epoxide ring attached to an ethyl group.

Also known as 1,2-butylene oxide, 1,2-Epoxybutane belongs to the family of cyclic ethers.
The strained ring structure gives 1,2-Epoxybutane its characteristic chemical reactivity.

1,2-Epoxybutane normally appears as a clear and colorless liquid.
The relatively low boiling point of 1,2-Epoxybutane causes it to evaporate readily.

The boiling point of 1,2-Epoxybutane lies near 63°C.
With a density lower than water, 1,2-Epoxybutane forms an upper layer in many aqueous mixtures.

Water dissolves a limited amount of 1,2-Epoxybutane under ordinary conditions.
Alcohols, ethers and many organic solvents mix more readily with 1,2-Epoxybutane.

1,2-Epoxybutane contains a stereogenic carbon and can occur in different optical forms.
Commercial 1,2-Epoxybutane commonly contains a mixture of the two enantiomers.

Alcohols can open the epoxide ring of 1,2-Epoxybutane to produce ether alcohols.
Amines react with 1,2-Epoxybutane to form functional amino alcohol derivatives.

Water can convert 1,2-Epoxybutane into butanediol under suitable reaction conditions.
Acids and bases can accelerate many ring-opening reactions involving 1,2-Epoxybutane.

1,2-Epoxybutane functions as a building block for specialty organic compounds.
Chemical manufacturers use 1,2-Epoxybutane to introduce hydroxybutyl functionality into molecular structures.

Polymerization can convert 1,2-Epoxybutane into polyether materials.
Copolymers containing 1,2-Epoxybutane can provide adjustable flexibility and hydrophobicity.

Polyol manufacturers may use 1,2-Epoxybutane to modify the properties of polyether chains.
The ethyl substituent of 1,2-Epoxybutane can increase the hydrophobic character of resulting products.

Surfactant intermediates can be prepared through controlled reactions involving 1,2-Epoxybutane.
1,2-Epoxybutane helps manufacturers adjust solubility and surface activity in selected derivatives.

Specialty lubricant additives may contain components derived from 1,2-Epoxybutane.
Functional derivatives of 1,2-Epoxybutane can support lubrication and formulation performance.

Organic synthesis uses 1,2-Epoxybutane in reactions requiring a reactive four-carbon building block.
Temperature, catalyst and reactant selection determine the products obtained from 1,2-Epoxybutane.

Industrial production of 1,2-Epoxybutane can involve the epoxidation of suitable butene feedstocks.
Purification by distillation provides 1,2-Epoxybutane with controlled chemical purity.

Gas chromatography can determine the purity and residual component profile of 1,2-Epoxybutane.
Water content, acidity and color represent important quality parameters for 1,2-Epoxybutane.

Uses of 1,2-Epoxybutane:
1,2-Epoxybutane is used as a stabiliser in chlorinated hydrocarbon solvents — including trichloroethylene, perchloroethylene, methylene chloride, and 1,1,1-trichloroethane — where it scavenges acidic HCl generated by thermal or photolytic decomposition of the chlorinated solvent, preventing corrosion of metal equipment and degradation of the solvent; it is among the most commonly used epoxide stabilisers in this application alongside butylene oxide isomers and propylene oxide.
1,2-Epoxybutane is used as an industrial monomer in ring-opening polymerisation (ROP) to produce poly(1,2-butylene oxide) (PBO), block copolymers with ethylene oxide or propylene oxide, and as an initiator for the synthesis of complex macromolecular architectures including grafted polyamides and segmented copolymers with controlled molecular weight and narrow dispersity; it offers high polymerisability and low susceptibility to chain-transfer reactions relative to other epoxide monomers.
1,2-Epoxybutane is used to functionalise polyethyleneimine (PEI) via ring-opening of the epoxide by the amine groups, introducing hydroxybutyl substituents on the polymer backbone to produce oxidation-stable adsorbents for post-combustion CO₂ capture from power plant flue gas — the hydroxylated PEI shows significantly improved stability under oxidative conditions compared with unmodified PEI while maintaining high CO₂ adsorption capacity.
1,2-Epoxybutane is used as a chiral building block in asymmetric synthesis; the (R)- and (S)-enantiomers (CAS 3760-95-0 and 30608-62-9 respectively) are used in the preparation of enantiomerically enriched intermediates for pharmaceuticals, agrochemicals, and specialty fine chemicals requiring a chiral 1,2-diol, amino alcohol, or epoxide-derived stereocentre.
1,2-Epoxybutane undergoes characteristic ring-opening reactions with a wide range of nucleophiles to give useful 2-substituted 1-butanol derivatives: with HCl → 1-chloro-2-butanol (chlorohydrin); with water (acid or base catalysis) → 1,2-butanediol; with amines → amino alcohols; with alcohols → 2-alkoxy-1-butanols; with carboxylic acids → 2-acyloxy-1-butanols; with H₂S → mercaptobutanols; with CO₂ → cyclic carbonate (butylene carbonate); all useful industrial intermediates.
1,2-Epoxybutane is used as an intermediate in the synthesis of speciality surfactants, polyurethane prepolymers, and hydraulic fluids, and as a reactive diluent or chain extender in epoxy resin systems where its lower viscosity compared with longer-chain epoxides improves processability; it is also used in the preparation of glycol ethers, emulsifiers, and corrosion inhibitors.

Benefits and Advantages of 1,2-Epoxybutane:
The strained three-membered oxirane ring of 1,2-epoxybutane provides exceptional electrophilic reactivity, enabling ring-opening with a wide variety of nucleophiles (amines, alcohols, thiols, carboxylates, halides, water) under mild conditions (0–80°C, acid or base catalysis, or without catalyst) — a breadth of reactivity not achievable with analogous non-strained electrophiles, making it an exceptionally versatile monomer and bifunctional intermediate.
The ethyl substituent of 1,2-epoxybutane imparts higher lipophilicity (logP 0.68 vs 0 for propylene oxide) and lower water miscibility than propylene oxide or ethylene oxide, while maintaining sufficient water solubility (86.8 g/L) for aqueous-phase reactions — a property balance that makes PBO and its ring-opening products useful as amphiphilic building blocks in surfactant and block copolymer design.
1,2-Epoxybutane is commercially available as the racemate and as enantiopure (R)- and (S)-enantiomers, enabling both industrial-scale bulk chemistry (racemate) and precision asymmetric synthesis (enantiomers) from the same compound class; the stereochemical integrity of the epoxide is retained in SN2-type ring-opening, providing predictable stereocontrol in downstream synthesis.
The high polymerisability of 1,2-epoxybutane combined with its low susceptibility to chain-transfer reactions (relative to propylene oxide) makes it particularly valuable in controlled/living ROP — producing well-defined PBO polymers with narrow molecular weight distributions — important for the design of precision block copolymer materials for drug delivery, nanofiltration membranes, and solid electrolytes.

Features of 1,2-Epoxybutane:
1,2-Epoxybutane is a clear, colourless, volatile liquid with a pungent, unpleasant odour; it is highly flammable (flash point −15°C); it forms explosive mixtures with air at ambient temperature (1.7–19.0% V/V); vapours are heavier than air (vapour density 2.49) and may accumulate along floors and in low-lying spaces; boiling point 63°C; melting point −129.5°C (−150°C lit.); density 0.829 g/cm³ at 25°C; pH 7 at 50 g/L at 20°C.
1,2-Epoxybutane is soluble in water (86.8 g/L at 25°C; readily biodegradable 80–90% in 28 days, ISO 14593); miscible with ethanol, ether, acetone, chloroform, and most organic solvents; logP (o/w) 0.68 at 25°C (bioaccumulation not expected, ECHA); it is not a PBT or vPvB substance; aquatic toxicity: LC50 >100 mg/L (fish, 96 h); EC50 70 mg/L (Daphnia, 48 h); EC50 >500 mg/L (algae, 72 h); EC50 ~900 mg/L (activated sludge, 30 min).
Key reactivity features: the epoxide undergoes acid-catalysed ring-opening (electrophilic activation at the more substituted carbon) and base-catalysed ring-opening (SN2 attack at the less hindered CH₂); it may polymerise violently if contaminated with acids, alkali hydroxides, or metallic chlorides (AlCl₃); may polymerise exothermically with heat evolution if contaminated, potentially rupturing containers — stabilisation is required for storage and transport (UN 3022 proper shipping name: 1,2-BUTYLENE OXIDE, STABILIZED).
1,2-Epoxybutane is incompatible with copper and copper alloys (forms explosive acetylide-type complexes at elevated temperature), strong oxidising agents, alkali hydroxides, ammonia, chlorine, acids, bases, alcohols, metallic salts, and metallic chlorides (AlCl₃ as polymerisation catalyst); it reacts violently with water under acidic or basic conditions at elevated temperature.

Chemical Properties of 1,2-Epoxybutane:
1,2-Epoxybutane has IUPAC name 2-ethyloxirane, molecular formula C₄H₈O, molecular weight 72.11 g/mol, SMILES CCC1CO1, InChI=1S/C4H8O/c1-2-4-3-5-4/h4H,2-3H2,1H3, InChIKey RBACIKXCRWGCBB-UHFFFAOYSA-N; PubChem CID 7834; ChemSpider 7546; ECHA InfoCard 100.003.127; DTXSID6020569; RTECS EK3675000; UNII FR67H5388O; EC 203-438-2; CB number CB5263486.
1,2-Epoxybutane is an aliphatic epoxide (oxirane); ring-opening chemistry: (1) acid-catalysed ring-opening with nucleophiles (HCl, H₂O, ROH, RCO₂H) gives 2-substituted 1-butanols via Markovnikov-selectivity; (2) base-catalysed / SN2 ring-opening with amines, thiols, carboxylates at CH₂ gives 1-substituted 2-butanols; (3) ring-opening polymerisation (ROP) — cationic, anionic, or coordination-insertion — gives poly(1,2-butylene oxide) homopolymers and block copolymers; (4) reaction with CO₂ → 1,2-butylene carbonate (cyclic carbonate); (5) isomerisation over Lewis acid → methyl ethyl ketone (MEK) / n-butyraldehyde.
1,2-Epoxybutane is produced by the oxidation of 1-butene: (a) epoxidation with peroxyacids (mCPBA, peracetic acid) — laboratory/specialty scale; (b) transition-metal catalysed asymmetric epoxidation (Sharpless epoxidation with Ti-tartrate catalyst) for enantiopure production; (c) chlorohydrin process — 1-butene + HOCl → 1-chloro-2-butanol, then dehydrochlorination with NaOH → 1,2-epoxybutane; (d) industrial direct oxidation of 1-butene using titanium silicalite (TS-1) catalyst with H₂O₂, analogous to the Sumitomo propylene oxide process.
Toxicological summary: Rat oral LD50 = 900 mg/kg (ECHA); rabbit dermal LD50 = 1,743 mg/kg (RTECS); inhalation ATE 4h = 11.1 mg/L; mutagenic in Ames test (positive with/without metabolic activation, S. typhimurium, OECD TG 471); IARC Group 2B (possibly carcinogenic to humans) — NTP rat study: nasal cavity and alveolar/bronchial tumours; chronic inhalation causes degenerative lesions of nasal cavity in rats and mice; material is destructive to mucous membranes, upper respiratory tract, eyes, and skin.

Production of 1,2-Epoxybutane:
1,2-Epoxybutane is produced industrially by (1) the chlorohydrin process: 1-butene reacts with aqueous hypochlorous acid (HOCl, from Cl₂ + H₂O) to give a mixture of 1-chloro-2-butanol and 2-chloro-1-butanol chlorohydrins, which are then dehydrochlorinated with NaOH to give 1,2-epoxybutane; (2) direct catalytic epoxidation of 1-butene using titanium silicalite (TS-1) with hydrogen peroxide (H₂O₂) — a cleaner route; (3) peroxyacid epoxidation (peracetic acid or mCPBA) for laboratory and specialty grades; and (4) asymmetric epoxidation with Sharpless catalyst for enantiopure (R)- or (S)-enantiomers.
Commercial 1,2-epoxybutane is available as stabilised racemate (≥97%, ≥99% GC) and as enantiopure (R)- and (S)-enantiomers (≥97–99% ee); supplied stabilised to prevent polymerisation during transport (UN 3022 proper shipping name: 1,2-BUTYLENE OXIDE, STABILIZED); packaging: sealed, nitrogen-blanketed glass or steel containers; storage: 2–8°C or at/below ambient in a cool, dry, well-ventilated flammable-liquid storage facility; explosive mixture formation with air is possible at ambient temperature — intrinsically safe (Ex-rated) equipment required.

1,2-Epoxybutane Material Safety Data Sheet (MSDS):

Handling of 1,2-Epoxybutane:
1,2-Epoxybutane is a highly flammable liquid (flash point −15°C) that forms explosive vapour-air mixtures at ambient temperature (LEL 1.7%); handle only under a fume hood; keep away from all ignition sources (flames, sparks, hot surfaces, static discharge); use bonded and earthed equipment; no smoking; avoid generating and inhaling vapours — use filter type AX respirator or SCBA.
1,2-Epoxybutane is suspected of causing cancer (H351, IARC Group 2B) and shows mutagenic effects — minimise all exposure; use impervious gloves (fluorinated rubber, min. 0.7 mm, breakthrough >37 min, EN 374); wear flame-retardant antistatic protective clothing; chemicals that may cause violent polymerisation (acids, bases, AlCl₃) must be kept strictly separate during storage and handling.

1,2-Epoxybutane SDS:

Stability and Reactivity of 1,2-Epoxybutane:

Chemical stability:
1,2-Epoxybutane is chemically stable under standard ambient conditions in tightly closed, cool, dry containers away from heat and ignition sources.
1,2-Epoxybutane may polymerise violently if contaminated with acids, alkali hydroxides, or metallic chlorides (AlCl₃), with heat evolution and possible container rupture — stabilisation required for storage and transport.

Reactivity:
Vapours form explosive mixtures with air at ambient temperature (LEL 1.7%, UEL 19.0%); violent reactions are possible with strong oxidising agents, alkali hydroxides, ammonia, chlorine, acids, bases, alcohols, metallic salts, and metallic chlorides.
Violent polymerisation may be initiated by acids, alkali hydroxides, and metallic chlorides (AlCl₃).

Conditions to avoid:
All sources of ignition (flame, spark, hot surface, static discharge).
Warming above ambient (increases vapour pressure and explosion risk).
Contamination with acids, bases, AlCl₃, or other polymerisation initiators.
Contact with copper or copper alloys (incompatible — corrosion and complex formation).

Incompatible materials:
Copper and copper alloys (incompatible — do not use copper fittings or equipment).
Strong oxidising agents.
Alkali hydroxides (NaOH, KOH) — violent polymerisation.
Ammonia, chlorine, acids, bases, alcohols, metallic salts.
Aluminium chloride, metallic chlorides — violent polymerisation.

Hazardous decomposition products:
Carbon monoxide (CO) and carbon dioxide (CO₂) upon combustion.
Hazardous combustion gases and vapours in the event of fire; see Section 5.

Handling and Storage of 1,2-Epoxybutane:

Handling:
Work under fume hood; avoid inhaling substance/mixture; avoid generation of vapours/aerosols.
Keep away from open flames, hot surfaces, and sources of ignition; take precautionary measures against static discharge.
Immediately change contaminated clothing; apply preventive skin protection; wash hands and face after working.
Wear impervious gloves (fluorinated rubber ≥0.7 mm, EN 374), safety glasses, and flame-retardant antistatic protective clothing.
Filter type: AX (organic vapour with low boiling point); SCBA required when vapour concentrations cannot be controlled.

Storage:
Keep container tightly closed in a cool, dry, well-ventilated, flammable-liquid store.
Storage class (TRGS 510): Class 3 — Flammable liquids.
Keep away from heat, sources of ignition, copper/copper alloys, acids, bases, and polymerisation initiators.
Supplied stabilised for transport (UN 3022: 1,2-BUTYLENE OXIDE, STABILIZED).
Transport: ADR/RID/IMDG/IATA: UN 3022; Hazard Class 3; PG II; no marine pollutant.
Seveso III: Flammable liquids category.

First Aid Measures for 1,2-Epoxybutane:

Inhalation:
Immediately remove the affected person to fresh air; call a physician immediately.
If breathing has stopped: immediately apply artificial respiration; administer oxygen if necessary.
Symptoms: irritation of mucous membranes, cough, shortness of breath, headache, nausea; material is destructive to mucous membranes and upper respiratory tract.

Skin contact:
Take off immediately all contaminated clothing; rinse skin with water/shower.
Consult a physician; prolonged contact may cause delayed burns.

Eye contact:
After eye contact: rinse out with plenty of water; remove contact lenses; call an ophthalmologist immediately.

Ingestion:
Caution if victim vomits — risk of aspiration; keep airways free; pulmonary failure possible after aspiration of vomit.
Call a physician immediately; show the MSDS to the attending physician.

Firefighting Measures for 1,2-Epoxybutane:

Suitable extinguishing media:
Carbon dioxide (CO₂), foam, dry powder; not: water jet (risk of frothing and spread).

Specific hazards:
1,2-Epoxybutane is a highly flammable liquid forming explosive vapour-air mixtures at ambient temperature; vapours are heavier than air and may spread along floors to distant ignition sources and flash back; combustion produces toxic carbon oxides; pay attention to flashback; development of hazardous combustion gases or vapours in fire.
NFPA 704: Health 3 / Fire 3 / Reactivity 2 / W.

Protective equipment for firefighters:
SCBA must be worn in all fire situations; prevent skin contact; prevent fire extinguishing water from contaminating surface water or ground water; remove containers from danger zone and cool with water.

Accidental Release Measures for 1,2-Epoxybutane:

Personal precautions:
Do not breathe vapours or aerosols; avoid substance contact; ensure adequate ventilation; keep away from heat and sources of ignition; evacuate the danger area; do NOT let product enter drains — risk of explosion.

Environmental precautions:
Do not let product enter drains or water courses — risk of explosion in sewer systems; vapours heavier than air may accumulate in low-lying confined areas.

Clean-up methods:
Cover drains; collect, bind, and pump off spills; use liquid-absorbent material (e.g. Chemizorb®); take up carefully with absorbent material; dispose of properly; clean up affected area; use intrinsically safe (Ex-rated) equipment.

Exposure Controls / Personal Protective Equipment for 1,2-Epoxybutane:

Engineering controls:
Work exclusively under a fume hood or with full local exhaust ventilation; use closed-system transfer equipment; eliminate all ignition sources; use intrinsically safe (Ex-rated) electrical equipment throughout the work area.

Eye protection:
Safety glasses or chemical splash goggles tested to EN 166 (EU) or NIOSH (US).

Hand protection:
Impervious fluorinated rubber gloves (min. 0.7 mm layer thickness; breakthrough time >37 min; Vitoject® KCL 890 or equivalent, tested to EN 374); inspect before use; dispose of contaminated gloves.

Body protection:
Flame-retardant antistatic protective clothing; antistatic footwear.

Respiratory protection:
Filter type AX (organic vapour, low boiling point compounds) when vapours may be generated; SCBA for high concentrations, fire, or spill response.

1,2-Epoxybutane Identifiers:
CAS Number (racemate): 106-88-7
CAS Number (R): 3760-95-0
CAS Number (S): 30608-62-9
EC Number: 203-438-2
ECHA InfoCard: 100.003.127
RTECS: EK3675000
UNII: FR67H5388O
DTXSID: DTXSID6020569
PubChem CID (racemate): 7834
PubChem CID (R): 11147670
PubChem CID (S): 10898629
ChemSpider (racemate): 7546
ChemSpider (R): 9322778
ChemSpider (S): 9073889
CBNumber: CB5263486
IUPAC Name: 2-Ethyloxirane
Molecular Formula: C₄H₈O
Molecular Weight: 72.11 g/mol
SMILES: CCC1CO1
InChI: InChI=1S/C4H8O/c1-2-4-3-5-4/h4H,2-3H2,1H3
InChIKey: RBACIKXCRWGCBB-UHFFFAOYSA-N
LogP (o/w): 0.68 (25°C)
GHS Signal Word: Danger
GHS Hazard Statements: H225, H315, H319, H335, H351
GHS Precautionary Statements: P210, P280, P301+P312, P303+P361+P353, P308+P313
NFPA 704: Health 3 / Fire 3 / Reactivity 2 / W
UN Number: 3022
UN Proper Shipping Name: 1,2-BUTYLENE OXIDE, STABILIZED
Hazard Class: 3 (Flammable liquid)
Packing Group: II
IARC Classification: Group 2B (possibly carcinogenic to humans)
Ames Test: Positive (with and without metabolic activation, S. typhimurium, OECD TG 471)
Rat oral LD50: 900 mg/kg
Rabbit dermal LD50: 1,743 mg/kg
Inhalation ATE 4h: 11.1 mg/L
Aquatic: LC50 (fish, 96h) >100 mg/L; EC50 (Daphnia, 48h) 70 mg/L; not PBT/vPvB
Biodegradability: 80–90% in 28 d (readily biodegradable, ISO 14593)
Storage Class (TRGS 510): 3 — Flammable liquids
Seveso III: Flammable liquids

Properties of 1,2-Epoxybutane:
Physical state: Liquid
Appearance: Clear, colourless liquid
Odour: Pungent, unpleasant, ethereal
Molecular formula: C₄H₈O
Molecular weight: 72.11 g/mol
Melting point: −129.5°C (ECHA); −150°C (lit.)
Boiling point: 63°C (lit.); 65°C (lit.)
Flash point: −15°C (closed cup)
Autoignition temperature: 370°C (DIN 51794)
Explosive limits: 1.7–19.0% (V/V)
Density: 0.829 g/cm³ at 25°C
Vapour density: 2.49 (air = 1)
Vapour pressure: 187 hPa (20°C)
Kinematic viscosity: 0.51 mm²/s (20°C); 0.42 mm²/s (40°C)
Dynamic viscosity: 0.421 mPa·s (20°C); 0.34 mPa·s (40°C)
Water solubility: 86.8 g/L (25°C)
LogP (o/w): 0.68 (25°C)
pH: 7 at 50 g/L, 20°C
GHS Classification: Danger — H225, H315, H319, H335, H351
IARC: Group 2B
Storage: Cool, dry, tightly closed; away from ignition sources; intrinsically safe equipment

1,2-Epoxybutane Properties — Specifications:
Product name: 1,2-Epoxybutane (1,2-Butylene oxide, stabilised)
CAS Number: 106-88-7
EC Number: 203-438-2
Molecular Formula: C₄H₈O
Molecular Weight: 72.11 g/mol
Purity (GC): ≥97%; ≥99% (high purity); enantiopure (R) and (S) ≥97% ee
Appearance: Clear, colourless liquid
Boiling point: 63°C
Flash point: −15°C (closed cup)
Density: 0.829 g/cm³ (25°C)
Water solubility: 86.8 g/L (25°C)
Supplied: Stabilised for transport (UN 3022)
Storage: 2–8°C or cool/ambient; tightly closed; away from ignition sources; flammable-liquid store; no copper fittings
Packaging: Sealed nitrogen-blanketed glass or steel containers
Documents: CoA (Certificate of Analysis), MSDS/SDS available

Names of 1,2-Epoxybutane:
1,2-Epoxybutane
2-Ethyloxirane
Ethyloxirane
1,2-Butylene oxide
1,2-Butene oxide
Butylene oxide
1-Butene oxide
n-Butylene oxide
Ethyl ethylene oxide
1,2-Epoxy-butane
RTECS EK3675000
UNII FR67H5388O
PubChem CID 7834
ChemSpider 7546
CB5263486
CAS 106-88-7
EINECS 203-438-2
UN 3022