General · EdgepediaSeptember 17, 20267 min read

1,4-Butanediol

1,4-Butanediol (also called 1,4-BDO, 1,4-BD, or tetramethylene glycol) is a four-carbon diol with the formula HO(CH₂)₄OH, a colorless, viscous, odorless liquid that is miscible with water and serves as a bulk intermediate for tetrahydrofuran, γ-butyrolactone, and engineering plastics. It is one of four stable structural isomers of butanediol, the others being the 1,2-, 1,3-, and 2,3-isomers.¹^•² The compound was first described in 1890 and has since become a large-volume commodity chemical, with annual production in the range of one million metric tons and world capacity around 2.1 million tons per year as of 2011.³^•⁴^•⁵

Key fact	Detail
Identity	CAS 110-63-4; molecular formula C₄H₁₀O₂; molar mass 90.12 g/mol; synonyms include 1,4-butylene glycol and 1,4-tetramethylene glycol¹^•⁶
Physical properties	Boiling point 230 °C; melting point about 20 °C (16 °C by one source); density 1.017 g/mL at 25 °C; miscible with water; log Kow −0.83¹^•⁶^•²
Main production route	Reppe process: acetylene and formaldehyde form 2-butyne-1,4-diol, which is hydrogenated over modified nickel catalysts at 80–160 °C and 300 bar²^•⁷
Largest use	Roughly 45–52% of consumption goes to tetrahydrofuran; about 25% to polybutylene terephthalate; γ-butyrolactone is the next-largest derivative⁷^•⁸
Human metabolism	After ingestion it is converted to γ-hydroxybutyrate (GHB) by alcohol dehydrogenase and aldehyde dehydrogenase; ethanol and fomepizole competitively block this conversion³
GHS classification	H302 (harmful if swallowed) and H336 (may cause drowsiness or dizziness); rat oral LD50 1,525 mg/kg⁹
Bio-based production	Novamont opened the first commercial-scale bio-based BDO plant (30,000 tons per year) in Italy in 2016; the QIRA process ferments plant-based sugars and, according to BASF, can save up to 86% of greenhouse gas emissions versus fossil BDO¹⁰^•¹¹

Physical and chemical properties

1,4-Butanediol is a colorless, viscous liquid with a high boiling point of 230 °C and a melting point near room temperature, about 20 °C, so it can solidify in a cool room; one supplier lists 16 °C.¹^•⁶ Its density is 1.017 g/mL at 25 °C, slightly greater than that of water, and its vapor density relative to air is 3.1.⁶^•¹ The two terminal hydroxyl groups make it a difunctional building block: each end reacts with dicarboxylic acids to form polyesters, with diisocyanates to form polyurethanes, and with phosgene to form polycarbonates.¹² The compound is combustible, with a flash point of 121 °C (open cup) and an auto-ignition temperature of 350 °C, and it reacts with strong oxidants.¹

Industrial production

The Reppe route. The first commercial route, and still the most embedded in the industry, starts from acetylene and formaldehyde, which react under pressure to form 2-butyne-1,4-diol; a second stage hydrogenates the butynediol to 1,4-butanediol.⁷^•² On a large industrial scale this hydrogenation runs continuously over modified nickel catalysts at 80–160 °C and 300 bar.²

Non-acetylenic routes. In 1979 Mitsubishi Chemical developed a route based on the oxidative acetoxylation of butadiene with acetic acid, followed by hydrogenation and hydrolysis; in 1990 Arco Chemical introduced a route from propylene oxide via isomerization to allyl alcohol and hydroformylation; and in the mid-1990s Davy Technology developed a route in which maleic anhydride is esterified and the ester hydrogenated.⁷ By 2011 the world capacity split by feedstock was 39% butadiene, 28% acetylene, 23% butane, and 10% propylene.⁵

Uses and derivatives

The dominant use is conversion to tetrahydrofuran (THF), a cyclic ether used mainly to make polytetramethylene ether glycol (PTMEG), the precursor of spandex elastic fibers, and also used as a solvent.⁵^•⁷ A 1983 US end-use profile put THF at 60% of consumption, γ-butyrolactone and derivatives at 17%, polybutylene terephthalate at 14%, polyurethane elastomers at 6%, and other uses at 3%; more recent estimates place THF near half of global consumption and PBT near a quarter.²^•⁷

Dehydration to THF. THF is produced by acid-catalyzed dehydrative cyclization of 1,4-butanediol. The reaction is inhibited by the water it generates, so processes use reactive distillation, which removes water as it forms; Mitsubishi Chemical's process, running a 60,000 ton-per-year plant in Japan, uses a homogeneous liquid-phase reaction with reactive distillation and an inexpensive catalyst.¹³^•⁵ Laboratory and alternative catalysts include the ion-exchange resin Amberlyst-15, zirconium sulfate, and supported heteropolyacids.¹³

Polymers. As a monomer, 1,4-butanediol enters polybutylene terephthalate (PBT) resins, polybutylene succinate (PBS), and polybutylene adipate-co-terephthalate (PBAT), and serves as a chain extender and cross-linking agent in polyurethane elastomers; it is also used as a solvent, a humectant, and an intermediate for plasticizers.²^•¹²

Bio-based production

Until 2011, 1,4-butanediol was produced solely from petrochemical feedstocks.⁴ Metabolic engineering then established fermentative routes in engineered Escherichia coli from sugars such as dextrose and sucrose.¹⁴ In 2016 Novamont opened the world's first commercial-scale bio-based BDO facility at Bottrighe, Italy, producing 30,000 tons per year using Genomatica's process.¹⁰ BASF has produced commercial volumes of renewable BDO under license from Genomatica and, through an agreement with Qore LLC, a joint venture of Cargill and HELM AG, gains long-term access to QIRA bio-based BDO made by fermenting plant-based sugars from field corn; the first commercial quantities were expected in the first quarter of 2025, and the company states the product can save up to 86% of greenhouse gas emissions compared with fossil-derived BDO.¹¹

Pharmacology and misuse

When ingested, 1,4-butanediol is a prodrug of γ-hydroxybutyrate (GHB), a central nervous system depressant. The conversion proceeds in two enzymatic steps: alcohol dehydrogenase oxidizes the diol to γ-hydroxybutyraldehyde, and aldehyde dehydrogenase converts the aldehyde to GHB.³ In a controlled study of eight healthy volunteers given 25 mg/kg orally, 1,4-butanediol was absorbed quickly, reaching peak plasma concentration at 24 ± 12 minutes with an elimination half-life of 39.3 ± 11 minutes; GHB appeared in plasma within 5 minutes and peaked at 45.6 ± 19.7 mg/L about 39 minutes after ingestion.¹⁵ Some subjects cleared the compound much more slowly, a difference that correlated with a variant haplotype of the alcohol dehydrogenase gene ADH-IB.¹⁵ Ethanol competes for alcohol dehydrogenase and delays the conversion, which can postpone the onset of GHB effects and complicate overdose presentation.³^•¹⁶

Because of this metabolism, 1,4-butanediol has been abused for its euphoric and sedative effects and has been marketed illicitly as a GHB substitute. A 2001 New England Journal of Medicine case series documented toxic episodes with vomiting, incontinence, confusion, ataxia, respiratory depression, and death among users.¹⁷ Reviews describe high addiction potential and potentially severe withdrawal, which can be a medical emergency.³ In the United States, distributing 1,4-butanediol as an illegal analog of GHB has been prosecuted criminally; in 2016 a former police officer was convicted on four counts of distributing and possessing with intent to distribute the compound.¹⁸

Safety

Under occupational classification, 1,4-butanediol carries the GHS hazard statements H302, harmful if swallowed, and H336, may cause drowsiness or dizziness, with the central nervous system as the target organ; the rat oral LD50 is 1,525 mg/kg.⁹^•⁶ The International Chemical Safety Card notes that short-term exposure may affect the central nervous system and cause narcosis, that the liquid is combustible, and that it should be stored separated from strong oxidants.¹ The US National Toxicology Program reviewed the compound's metabolism, disposition, and toxicity, finding that rapid and extensive conversion to GHB makes the toxicological profile of 1,4-butanediol reflect that of GHB itself.¹⁹

References

Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Alcohols, ethers, and organooxygen groups › Alcohols and polyols › Diols and polyols › Glycols and alkane polyols › Butanediols (1,2-, 1,3-, 1,4-, 2,3-)

Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026

Notice something wrong?