Hubbry Logo
2-Butoxyethanol2-ButoxyethanolMain
Open search
2-Butoxyethanol
Community hub
2-Butoxyethanol
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
2-Butoxyethanol
2-Butoxyethanol
2-Butoxyethanol
View on Wikipedia
from Wikipedia
2-Butoxyethanol
2-Butoxyethanol
2-Butoxyethanol
2-Butoxyethanol molecule
Names
Preferred IUPAC name
2-Butoxyethanol
Other names
2-Butoxyethanol
Butyl cellosolve
Butyl glycol
Butyl monoether glycol
EGBE (ethylene glycol monobutyl ether)
Dowanol EB
Eastman EB solvent
2-BE
EGMBE
Butyl oxitol
Ektasolve EB
Jeffersol EB
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.550 Edit this at Wikidata
EC Number
  • 203-905-0
RTECS number
  • KJ8575000
UNII
UN number 1993, 2810, 2369
  • InChI=1S/C6H14O2/c1-2-3-5-8-6-4-7/h7H,2-6H2,1H3 ☒N
    Key: POAOYUHQDCAZBD-UHFFFAOYSA-N ☒N
  • InChI=1/C6H14O2/c1-2-3-5-8-6-4-7/h7H,2-6H2,1H3
    Key: POAOYUHQDCAZBD-UHFFFAOYAB
  • OCCOCCCC
Properties
C6H14O2
Molar mass 118.176 g·mol−1
Appearance Clear, colorless liquid
Density 0.90 g/cm3, liquid
Melting point −77 °C (−107 °F; 196 K)
Boiling point 171 °C (340 °F; 444 K)
Miscible (and in most organic solvents)
Vapor pressure 0.8 mmHg[1]
Acidity (pKa) High pKa for −OH group
1.4198 (20 °C)[2]
Viscosity 2.9 cP at 25 °C (77 °F)
2.08 D[2]
Hazards
GHS labelling:
GHS06: ToxicGHS07: Exclamation markGHS08: Health hazard
Danger
H227, H302, H311, H315, H319, H330, H336, H361, H370, H372
P201, P202, P210, P260, P261, P264, P270, P271, P280, P281, P284, P301+P312, P302+P352, P304+P340, P305+P351+P338, P307+P311, P308+P313, P310, P312, P314, P320, P321, P322, P330, P332+P313, P337+P313, P361, P362, P363, P370+P378, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
2
0
Flash point 67 °C (153 °F; 340 K)
245 °C (473 °F; 518 K)
Explosive limits 1.1–12.7%[1]
Lethal dose or concentration (LD, LC):
1230 mg/kg (mouse, oral)
470 mg/kg (rat, oral)
300 mg/kg (rabbit, oral)
1200 mg/kg (guinea pig, oral)
1480 mg/kg (rat, oral)[3]
450 ppm (rat, 4 h)
700 ppm (mouse, 7 h)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 50 ppm (240 mg/m3) [skin][1]
REL (Recommended)
 TWA 5 ppm (24 mg/m3) [skin][1]
IDLH (Immediate danger)
 700 ppm[1]
Safety data sheet (SDS) [1]
Related compounds
Related ethers
 2-Methoxyethanol
2-Ethoxyethanol
Related compounds
 Ethylene glycol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

2-Butoxyethanol is an organic compound with the chemical formula BuOC2H4OH (Bu = CH3CH2CH2CH2). This colorless liquid has a sweet, ether-like odor, as it derives from the family of glycol ethers, and is a butyl ether of ethylene glycol. As a relatively nonvolatile, inexpensive solvent, it is used in many domestic and industrial products because of its properties as a surfactant. It is a known respiratory irritant[4] and can be acutely toxic, but animal studies did not find it to be mutagenic, and no studies suggest it is a human carcinogen.[5] A study of 13 classroom air contaminants conducted in Portugal reported a statistically significant association with increased rates of nasal obstruction and a positive association below the level of statistical significance with a higher risk of obese asthma and increased body mass index.[6]

Properties

[edit]

Miscibility with water

[edit]

Miscibility of 2-butoxyethanol with water depends on temperature. Depending on the composition of the mixture, the two liquids are partially miscible. This mixture shows both a lower and an upper critical solution temperature: below around 49 °C (lower critical solution temperature), the liquids are completely miscible. The same is true for temperatures above around 130 °C (upper critical solution temperature). Between these temperatures, however, the liquids do not mix in all proportions and two phases might appear, each of which is formed by various ratios of the two liquids.[7][8]

Production

[edit]

2-Butoxyethanol is commonly obtained through two processes; the ethoxylation reaction of butanol and ethylene oxide in the presence of a catalyst:

C2H4O + C4H9OH → C4H9OC2H4OH

or the etherification of butanol with 2-chloroethanol.[9] 2-Butoxyethanol can be obtained in the laboratory by performing a ring opening of 2-propyl-1,3-dioxolane with boron trichloride.[10] It is often produced industrially by combining ethylene glycol and butyraldehyde in a Parr reactor with palladium on carbon.[11]

In 2006, the European production of butyl glycol ethers amounted to 181 kilotons, of which approximately 50% (90 kt/a) was 2-butoxyethanol. World production is estimated to be 200 to 500 kt/a, of which 75% is for paints and coatings[12] and 18% for metal cleaners and household cleaners.[13] In the US, it is considered a high production volume chemical because more than 100 million pounds of this chemical are produced per year.[13]

Uses

[edit]

2-Butoxyethanol is a glycol ether with modest surfactant properties, which can also be used as a mutual solvent (soluble in both water and oil).

Commercial uses

[edit]

2-Butoxyethanol is a solvent for paints and surface coatings, as well as cleaning products and inks.[12][14] Products that contain 2-butoxyethanol include acrylic resin formulations, asphalt release agents, firefighting foam, leather protectors, oil spill dispersants, degreaser applications, photographic strip solutions, whiteboard and glass cleaners, liquid soaps, cosmetics, dry cleaning solutions, lacquers, varnishes, herbicides, latex paints, enamels, printing paste, varnish removers, and silicone caulk. Products containing this compound are commonly found at construction sites, automobile repair shops, print shops, and facilities that produce sterilizing and cleaning products. It is the main ingredient of many home, commercial and industrial cleaning solutions. Since the molecule has both polar and non-polar ends, 2-butoxyethanol is useful for removing both polar and non-polar substances, like grease and oils. It is also approved by the U.S. FDA to be used as direct and indirect food additives, which include antimicrobial agents, defoamers, stabilizers, and adhesives.[15]

In the petroleum industry

[edit]

2-Butoxyethanol is commonly produced for the oil industry because of its surfactant properties.[16]

In the petroleum industry, 2-butoxyethanol is a component of fracturing fluids, drilling stabilizers, and oil slick dispersants for both water-based and oil-based hydraulic fracturing.[13][clarification needed] When liquid is pumped into the well, the fracturing fluids are pumped under extreme pressure, so 2-butoxyethanol is used to stabilize them by lowering the surface tension.[13] As a surfactant, 2-butoxyethanol absorbs at the oil-water interface of the fracture.[17] The compound is also used to facilitate the release of the gas by preventing congealing.[13] It is also used as a crude oil–water coupling solvent for more general oil well workovers.[13] Because of its surfactant properties, it is a major constituent (30–60% w/w) in the oil spill dispersant Corexit 9527,[18] which was widely used in the aftermath of the 2010 Deepwater Horizon oil spill.[15]

Safety

[edit]

2-Butoxyethanol has a low acute toxicity, with LD50 of 2.5 g/kg in rats.[12] Laboratory tests by the U.S. National Toxicology Program have shown that only sustained exposure to high concentrations (100–500 ppm) of 2-butoxyethanol can cause adrenal tumors in animals.[19] American Conference of Governmental Industrial Hygienists (ACGIH) reports that 2-butoxyethanol is carcinogenic in rodents.[20] These rodent tests may not directly translate to carcinogenicity in humans, as the observed mechanism of cancer involves the rodents' forestomach, which humans lack.[21] OSHA does not regulate 2-butoxyethanol as a carcinogen.[22] 2-Butoxyethanol has not been shown to penetrate shale rock in a study conducted by Manz.[23]

Disposal and degradation

[edit]

2-Butoxyethanol can be disposed of by incineration. It was shown that disposal occurs faster in the presence of semiconductor particles.[9] 2-Butoxyethanol usually decomposes in the presence of air within a few days by reacting with oxygen radicals.[24] It has not been identified as a major environmental contaminant, nor is it known to bio-accumulate.[25] 2-Butoxyethanol biodegrades in soils and water, with a half life of 1–4 weeks in aquatic environments.[15]

Human exposure

[edit]

2-Butoxyethanol most commonly enters the human body system through dermal absorption, inhalation, or oral consumption of the chemical.[9] The ACGIH threshold limit value (TLV) for worker exposure is 20 ppm, which is well above the odor detection threshold of 0.4 ppm. Blood or urine concentrations of 2-butoxyethanol or the metabolite 2-butoxyacetic acid may be measured using chromatographic techniques. A biological exposure index of 200 mg 2-butoxyacetic acid per g creatinine has been established in an end-of-shift urine specimen for U.S. employees.[26][27] 2-Butoxyethanol and its metabolites fall to undetectable levels in urine after about 30 hours in men.[28]

Animal studies

[edit]

Harmful effects have been observed in nonhuman mammals exposed to high levels of 2-butoxyethanol. Developmental effects were seen in a study that exposed pregnant Fischer 344 rats, a type of laboratory rat, and New Zealand white rabbits to varying doses of 2-butoxyethanol. At 100 ppm (483 mg/m3) and 200 ppm (966 mg/m3) exposure, statistically significant increases were observed in the number of litters with skeletal defects. Additionally, 2-butoxyethanol was associated with a significant decrease in maternal body weight, uterine weight, and number of total implants.[29] 2-Butoxyethanol is metabolized in mammals by the enzyme alcohol dehydrogenase.[28]

Neurological effects have also been observed in animals exposed to 2-butoxyethanol. Fischer 344 rats exposed to 2-butoxyethanol at concentrations of 523 ppm and 867 ppm experienced decreased coordination. Male rabbits showed a loss of coordination and equilibrium after exposure to 400 ppm of 2-butoxyethanol for two days.[30]

When exposed to 2-butoxyethanol in drinking water, both F344/N rats and B63F1 mice showed negative effects. The range of exposure for the two species was between 70 mg/kg body weight per day to 1300 mg/kg body weight per day. Decreased body weight and water consumption were seen for both species. Rats had reduced red blood cell counts and thymus weights, as well as lesions in the liver, spleen, and bone marrow.[29]

Regulation in Canada

[edit]

Environment and Health Canada recommended that 2-butoxyethanol be added to Schedule 1 of the Canadian Environmental Protection Act, 1999 (CEPA).[31] Under these regulations, products containing 2-butoxyethanol are to be diluted below a certain concentration. Only those in which the user performs the required dilution are required to include it on labelling information.[32]

Regulation in the US

[edit]

2-Butoxyethanol is listed in California as a hazardous substance and the state sets an 8 hour average airborne concentration exposure limit at 25 ppm,[33] and in California employers are required to inform employees when they are working with it.[34]

2-Butoxyethanol is prohibited from use as a chemical additive in hydraulic fracturing fluids (Rule 437, Table 437-1[35]) in Colorado where all chemicals used in downhole operations are required to be disclosed (§34-60-132 C.R.S.[36]) to the Energy and Carbon Management Commission.

It is approved by the Food and Drug Administration as "an indirect and direct food additive for use as an antimicrobial agent, defoamer, stabilizer and component of adhesives",[15] and also "may be used to wash or assist in the peeling of fruits and vegetables" and "may be safely used as components of articles intended for use in packaging, transporting & holding food".[37] After its deletion from a UN list of substances requiring special toxicity labeling in 1994, and a subsequent petition by the American Chemistry Council, 2-butoxyethanol was removed from the U.S. Environmental Protection Agency's list of hazardous air pollutants in 2004.[38][39] The safety of products containing 2-butoxyethanol as normally used is defended by the industry trade groups the American Chemistry Council[39] and the Soap and Detergent Association.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

2-Butoxyethanol

View on Grokipedia
from Grokipedia

is a colorless, high-boiling liquid with the molecular formula C₆H₁₄O₂ and a mild -like , classified as a glycol that functions as a where one methyl of is substituted by a butoxy group. Its physical properties include a of 171 °C, a of -70 °C, and miscibility with and many organic , enabling its role in dissolving both hydrophilic and hydrophobic substances. Industrially produced via the reaction of with n-butanol, it serves primarily as a versatile in applications such as water-based paints, varnishes, household cleaners, inks, and , where it enhances product stability and efficacy by coupling with oil-dissolving power. However, empirical data from toxicological studies indicate moderate , with inhalation or dermal exposure at high levels causing , reduced , irritation to eyes and , and potential liver and damage, though it lacks evidence of carcinogenicity or mutagenicity in humans. Regulatory bodies have established exposure limits, such as OSHA's permissible exposure level of 50 ppm, to mitigate occupational risks while preserving its industrial utility.

History

Discovery and Early Development

2-Butoxyethanol emerged from early 20th-century advancements in glycol ether synthesis, pioneered by Carbide and Carbon Chemicals Corporation (predecessor to ) as part of efforts to develop superior industrial . The compound, synthesized via the reaction of with n-butanol, followed the 1920s patenting of analogous ethyl cellosolve by Dr. Charles O. Young, which established the foundational process for monoalkyl ether derivatives of . These developments addressed limitations of conventional alcohols, providing a solvent with enhanced solvency for resins, oils, and in lacquers and coatings. Commercialization accelerated in and as demand grew for versatile, high-boiling-point solvents in paints, inks, and cleaning formulations, where 2-butoxyethanol demonstrated superior coupling and penetration properties over or derivatives. By the mid-20th century, industrial production had scaled, reflecting its integration into expanding sectors. U.S. output reached 130 million pounds annually by 1972, underscoring its role in broadening applications beyond traditional options. This growth paralleled the petrochemical boom, with 2-butoxyethanol becoming a key E-series glycol by the .

Properties

Physical Characteristics

2-Butoxyethanol is a colorless with a mild, ether-like . Its molecular is C₆H₁₄O₂. The compound has a of 171 °C at standard . Its density is 0.90 g/cm³ at 20 °C, making it less dense than . The is approximately 0.8 mmHg at 20 °C, which corresponds to moderate volatility suitable for applications. 2-Butoxyethanol is fully miscible with and most organic solvents due to its amphiphilic featuring both hydrophobic butyl and hydrophilic ethoxyhydroxy groups.
Physical PropertyValueReference Conditions
Melting Point-75 °CLiterature value
67 °CClosed cup

Chemical Behavior and Solubility

2-Butoxyethanol demonstrates infinite with , forming homogeneous solutions in all proportions due to its polar hydroxyl group facilitating hydrogen bonding. This property distinguishes it from many non-polar ethers, which exhibit limited solubility, and enables its role in aqueous-based formulations. It is also fully miscible with organic solvents such as , , and acetone, enhancing its versatility as a co-solvent. The amphiphilic structure of 2-butoxyethanol, featuring a hydrophobic butyl chain and a hydrophilic hydroxyethoxy moiety, imparts surfactant-like properties that lower interfacial tension between immiscible phases. This dual nature allows it to bridge hydrophilic and hydrophobic substances, promoting stability in mixed solvent systems without forming traditional micelles at low concentrations. Under standard ambient conditions, 2-butoxyethanol remains chemically stable with minimal reactivity, showing no tendency for hazardous decomposition or polymerization. In biological environments, however, it is metabolized primarily through oxidation of the terminal alcohol group to form 2-butoxyacetic acid, reflecting its susceptibility to enzymatic .

Production

Industrial Synthesis Methods

The primary industrial method for synthesizing 2-butoxyethanol is the of anhydrous n-butanol with in the presence of a catalyst. This reaction proceeds via nucleophilic attack of the ion derived from n-butanol on the ring of , yielding the desired monoether product under controlled conditions of temperature (typically 120–180°C) and pressure (1–5 ) to ensure high conversion rates exceeding 90%. The process is highly efficient for large-scale operations, with raw material inputs dominated by petrochemical-derived and n-butanol, enabling cost-effective production due to the simplicity and scalability of the reactor systems employed. To optimize selectivity and minimize byproducts, the to n-butanol molar ratio is strictly controlled near 1:1, preventing excessive oligomerization that would form diethylene glycol monobutyl ether (up to 0.2% impurity) or higher analogs. Post-reaction purification involves under vacuum to separate the target compound ( 171.2°C), achieving technical-grade purity >99% while rejecting unreacted alcohols, , and trace glycols. This purification step is critical for downstream applications, as residual byproducts can affect performance, and modern processes incorporate of excess n-butanol to enhance overall yield and reduce waste. Less commonly, 2-butoxyethanol can be produced via the variant, alkylating or ethylene chlorohydrin with dibutyl sulfate under basic conditions using , though this route generates more inorganic salts and is disadvantaged by lower compared to the dominant . By 1983, U.S. production volumes exceeded 230 million pounds annually, reflecting the method's entrenched role in high-volume glycol .

Applications

Solvents in Coatings and Paints

2-Butoxyethanol functions as a key in protective surface coatings, including spray lacquers, quick-dry lacquers, enamels, varnishes, and paints, where it dissolves resins such as and synthetic polymers to achieve uniform formulations. Typical concentrations range from 1% to 30% by volume in these coatings, depending on the system, with 2–5% common in aqueous formulations to maintain stability and performance. Its high solvency power stems from a balance of hydrophilic and hydrophobic groups, allowing effective dissolution of both water-soluble and organic components while providing complete in and many organic solvents at . This enables superior control compared to some alternatives, reducing solution thickness for smoother application and improved flow during brushing or spraying. In quick-dry lacquers and enamels, 2-butoxyethanol's moderate evaporation rate supports enhanced drying characteristics and film leveling, promoting even surface formation without defects like orange peel or sagging. These properties contribute to its preference in industrial coatings for wood finishes and metal surfaces, where empirical testing shows better resin compatibility and application efficiency than faster-evaporating solvents alone.

Cleaning and Household Products

2-Butoxyethanol serves as a key in household and industrial formulations, enabling the dissolution of organic residues such as oils, greases, and dirt that are not readily water-soluble. Its amphiphilic properties allow it to couple hydrophobic soils with aqueous solutions, facilitating emulsification and removal during rinsing. This makes it particularly effective in products like cleaners, all-purpose spray cleaners, liquid soaps, floor strippers, and degreasers, where it enhances against stubborn contaminants. The compound's utility in these applications stems from its ability to dissolve greases and oils at low concentrations, typically sufficient for performance without requiring high dosages that could compromise formulation stability or cost. For instance, it improves the emulsifying action of soaps when incorporated as a mutual for mineral oils, allowing cleaners to handle both water-based and oil-based soils effectively. Historical data indicate its presence in over 430 cleaning products in as of , including general surface cleaners and spot removers, underscoring its widespread adoption in systems. , surveys from reported it in more than 740 products overall, with nearly half designated for household use, reflecting its role in enabling versatile, high-performance cleaners.

Petroleum Industry Uses

In the , 2-butoxyethanol serves primarily as a in fluids and hydraulic fracturing operations, where it reduces to enhance wettability and improve the dispersion of additives, thereby facilitating better penetration into formations. This property contributes to by minimizing loss to the formation and stabilizing emulsions in water-based systems. The compound also plays a role in (EOR) techniques, particularly in shale-rich reservoirs, acting as a mutual when combined with diluted to alter rock wettability and mobilize residual oil, with laboratory studies demonstrating increased recovery yields through processes. In pipeline and wellbore , 2-butoxyethanol is incorporated into cleaning compositions to dissolve scales and organic deposits, enabling effective removal without excessive mechanical intervention, as evidenced in formulations targeting FeS accumulation. These applications persist due to demonstrated benefits in yield optimization and , outweighing concerns in controlled industrial settings.

Toxicology

Acute Exposure Effects

Acute inhalation exposure to 2-butoxyethanol vapors primarily causes irritation to the mucous membranes of the eyes, nose, and upper respiratory tract, often accompanied by symptoms such as headache, nausea, dizziness, and a metallic taste in the mouth. Human studies indicate that mild ocular and nasal irritation may occur at concentrations around 25 ppm for short durations (10-120 minutes), while more pronounced effects, including throat irritation and belching, have been reported at levels up to 50 ppm. The odor threshold is detectable at 0.1-0.4 ppm, but sensory irritation thresholds are higher, with a no-observed-adverse-effect level (NOAEL) for discomfort and respiratory irritation established at 20 ppm in controlled human exposures. Recovery from these effects is typically rapid and complete upon cessation of exposure and removal to fresh air. Dermal contact with undiluted 2-butoxyethanol or concentrated solutions results in moderate , characterized by redness, dryness, and potential defatting of the , though it is not a severe sensitizer. Direct ocular exposure causes immediate severe , including , redness, and possible corneal damage, as evidenced by animal data corroborated by case reports. In a documented incident involving seven clerical workers, acute exposure led to severe immediate eye and upper respiratory , presyncope, and , resolving without long-term sequelae after prompt intervention. Hemolytic effects, a hallmark of acute high-dose exposure in rodents (observed at oral doses >100 mg/kg due to the metabolite butoxyacetic acid), are far less pronounced in humans owing to differences in red blood cell sensitivity and faster metabolic clearance of the metabolite. In vitro assessments confirm that human erythrocytes exhibit sub-hemolytic responses to butoxyacetic acid at concentrations that lyse rat cells, and clinical hemolysis remains rare in human acute exposures, even at levels causing systemic symptoms. Erythrocyte osmotic fragility does not significantly alter in humans following controlled inhalation exposures up to 87 ppm for 4 hours.

Chronic and Long-Term Risks

Chronic exposure to 2-butoxyethanol via or dermal routes in occupational settings has not demonstrated conclusive evidence of carcinogenicity in humans, with epidemiological studies showing no increased cancer incidence among exposed workers. , including National Toxicology Program (NTP) experiments at doses up to 250 ppm for two years, reported hemangiosarcomas in male mice and forestomach squamous cell carcinomas, but equivocal hepatocellular adenomas in female rats; however, these findings exhibit limited relevance to humans due to species-specific metabolic differences, such as greater susceptibility to in and absence of a forestomach in humans. The International Agency for Research on Cancer (IARC) classifies 2-butoxyethanol as Group 3 (not classifiable as to carcinogenicity to humans), citing inadequate human data and limited mechanistic concordance with rodent outcomes. High-dose animal models reveal potential liver and effects from repeated exposure, with intermediate-duration studies in s showing increased weights and histopathological changes at airborne concentrations exceeding 100 ppm, often secondary to and metabolite accumulation like butoxyacetic acid. In contrast, human occupational data from controlled environments with ventilation indicate minimal incidence of such organ toxicity; for instance, Agency for Toxic Substances and Disease Registry (ATSDR) reviews of worker cohorts exposed below 25 ppm report no consistent liver elevations or renal dysfunction, attributing lower risk to humans' reduced hemolytic sensitivity—human erythrocytes require over threefold higher concentrations for compared to cells. Dose-response analyses confirm a threshold below occupational exposure limits (e.g., ACGIH TLV of 20 ppm), where no-observed-adverse-effect levels (NOAELs) in translate to margins of exceeding 10-fold for humans after pharmacokinetic adjustments. The Cosmetic Ingredient Review (CIR) Expert Panel's 2025 amended assessment reaffirms the safety of butoxyethanol in at typical low concentrations (up to 5% in nail products, lower elsewhere), finding insufficient evidence to warrant revised restrictions despite re-examination of animal carcinogenicity data, as human dermal absorption and systemic exposure remain negligible under diluted use conditions. This counters claims of inherent long-term hazard by emphasizing empirical dose-response gaps between exaggerated animal models and real-world dilute applications, with no substantiated reproductive or developmental chronic risks beyond acute thresholds in either species.

Comparative Human and Animal Data

2-Butoxyethanol (2-BE) demonstrates marked differences in , largely attributable to variations in the and handling of its primary , butoxyacetic acid (BAA). In rats and mice, BAA accumulates systemically and exerts direct hemolytic effects on erythrocytes by altering integrity and osmotic fragility, leading to at relatively low doses. Humans, however, exhibit faster conjugation and of BAA via pathways producing and , which substantially attenuates erythrocyte damage and systemic . In vitro assessments of hemolytic potential confirm this disparity: , , and red blood cells undergo rapid when exposed to BAA concentrations as low as 1-2 mM, whereas human erythrocytes require concentrations exceeding 5 mM for comparable effects, with and cells displaying intermediate sensitivity. These findings align with in vivo observations where develop pronounced following oral or inhalation exposures, while non-human like rhesus monkeys tolerate chronic inhalation of 100-210 ppm for 30-90 days without hemolytic changes or respiratory distress. Acute toxicity metrics further illustrate these differences; the oral LD50 in rats is approximately 470-700 mg/kg, eliciting and secondary organ effects, compared to higher thresholds in less sensitive species. No human LD50 data exist due to ethical constraints, but controlled human exposures and pharmacokinetic modeling predict minimal hemolytic risk at occupational levels below 25 ppm, supported by the absence of blood dyscrasias in analogs. Epidemiological data from occupational cohorts exposed dermally or via to 2-BE in industrial settings (e.g., painting, cleaning) show no consistent evidence of or chronic hematological abnormalities, even at airborne concentrations up to 10-20 ppm over years, contrasting sharply with precautionary extrapolations from models that overestimate vulnerability. This underscores the necessity of prioritizing and higher data over rodent-derived endpoints for causal risk evaluation, as metabolic and physiological divergences render direct interspecies scaling unreliable without adjustment.

Environmental Impact

Fate and Degradation

2-Butoxyethanol undergoes primary degradation through aerobic microbial processes in environmental compartments such as and . Under aerobic conditions, it is readily biodegradable, with studies demonstrating substantial breakdown by adapted microbial populations within standard testing periods. The estimated half-life for follows kinetics, ranging from 1 to 4 weeks in aquatic and environments. In specifically, the biodegradation extends from 14 days to 8 weeks, reflecting variations in microbial activity and substrate availability. Bioaccumulation potential remains low due to its high water (miscible with water) and low (log Kow ≈ 0.83), which limit partitioning into lipid tissues and favor rapid in organisms. This compound does not meet criteria for under regulatory frameworks like those from the . Volatilization contributes minimally to attenuation, as indicated by its low Henry's law constant (≈ 2.4 × 10^{-8} atm-m³/mol), resulting in negligible from moist or dry soils and limited transfer from water to air. occurs slowly or not at all under environmental pH conditions, with no significant direct hydrolytic breakdown reported. Overall, aerobic dominates natural removal, supporting its classification as environmentally attenuating without persistent accumulation.

Ecological Toxicity

2-Butoxyethanol exhibits moderate acute toxicity to aquatic organisms, with 96-hour LC50 values for species such as (Oncorhynchus mykiss) ranging from 560 mg/L to 1,474 mg/L under static test conditions following Test Guideline 203. Similar results have been observed for and , indicating low to moderate sensitivity across primary trophic levels, with no pronounced chronic effects at sublethal concentrations in standard ecotoxicity assays. Environmental monitoring data reveal typical surface and concentrations of 2-butoxyethanol in the per liter (µg/L) range or below, often orders of magnitude lower than thresholds; for instance, effluents from industrial sources have measured approximately 0.03 mg/L, while predicted environmental concentrations from modeled releases remain far below LC50 values. This disparity underscores minimal risk to ecosystems under diffuse release scenarios, as rapid dilution and — with half-lives of 1–4 weeks in and —limit persistence. 2-Butoxyethanol demonstrates low potential, with a low (log Kow ≈ 0.83) and no evidence of through food chains, as partitioning favors aqueous phases over lipid tissues in biota. Ecotoxicological impacts are thus primarily associated with acute high-concentration events, such as spills, rather than chronic accumulation or trophic transfer, rendering widespread ecological disruption unlikely absent containment failures.

Regulations

United States Standards

The Occupational Safety and Health Administration (OSHA) establishes a permissible exposure limit (PEL) for 2-butoxyethanol in workplace air of 50 parts per million (ppm) as an 8-hour time-weighted average (TWA), with a skin notation indicating potential significant absorption through the skin, intact or abraded, which must be considered in exposure assessments. This limit, derived from earlier evaluations of acute toxicity data including hemolysis risks at higher concentrations, prioritizes controlling inhalation and dermal routes based on empirical evidence from animal and limited human studies showing reversible effects below this threshold. The National Institute for Occupational Safety and Health (NIOSH) recommends a more stringent REL of 5 ppm TWA (skin), reflecting cautious interpretation of data on respiratory irritation and potential systemic effects, though OSHA's PEL remains enforceable. Under the Toxic Substances Control Act (TSCA), 2-butoxyethanol is listed on the TSCA Chemical Substance Inventory as an active substance, subjecting it to reporting and recordkeeping requirements for manufacturers and importers exceeding certain thresholds, but without prohibitions on production, import, or use, indicating regulatory determination of manageable risks through existing exposure controls rather than outright restriction. The Environmental Protection Agency (EPA) previously included 2-butoxyethanol (as monobutyl ether) on the Clean Air Act's list of hazardous air pollutants but removed it in November 2004 following review of toxicological data, including low carcinogenic potential and adequate margins of safety from environmental exposures, emphasizing evidence-based delisting over precautionary persistence on the list. In hydraulic fracturing operations, federal and state disclosure requirements—such as those under the Bureau of Land Management's rules for and various state registries—mandate reporting of 2-butoxyethanol when used as a reducer or in fracturing fluids, without imposing a nationwide ban, as empirical monitoring has not demonstrated widespread uncontrollable releases necessitating prohibition. This approach aligns with TSCA and Clean Air Act frameworks, focusing on transparency and site-specific informed by degradation data and low potential rather than uniform curtailment.

Canadian and International Frameworks

In Canada, the 2-Butoxyethanol Regulations (SOR/2006-347), which established concentration limits for 2-butoxyethanol in products such as automobile cleaners (up to 10% w/w) and rug or carpet cleaners (up to 6% w/w), were repealed in 2025 and integrated into the broader Certain Products Containing Toxic Substances Regulations (SOR/2025-36). This consolidation, effective following publication in the Canada Gazette on March 12, 2025, streamlines oversight of toxic substances under the Canadian Environmental Protection Act, 1999, by maintaining product-specific concentration caps—such as limits below 6% w/w in general cleaning products—to mitigate health risks from dermal and inhalation exposure while permitting industrial applications with proper controls. The approach emphasizes risk-based exposure management over outright prohibition, aligning with assessments that tolerable concentrations (e.g., 11 mg/m³ in air) can safeguard public health when adhered to. Internationally, 2-butoxyethanol is regulated under the European Union's REACH framework (Regulation (EC) No 1907/2006), which classifies it as an irritant to and eyes (H315, H319) and acutely toxic via oral, dermal, and routes (Acute Tox. 3/4 categories), requiring registration, assessments, and exposure controls for manufacturers and importers without authorizing unrestricted high-volume use in products like (limited to 4% in certain hair dyes). Harmonized classification under the (EU) No 1272/2008, updated in 2022 to include specific hazard entries for 2-butoxyethanol, supports global consistency via the Globally Harmonized System (GHS) for labeling and safety data sheets, focusing on protective measures like ventilation and rather than substance bans. The International Agency for Research on Cancer (IARC) classifies 2-butoxyethanol as Group 3 (not classifiable as to its carcinogenicity to humans), based on limited evidence in animals and inadequate data in humans, reinforcing regulatory emphasis on acute and irritancy hazards over oncogenic s.

Industrial Significance

Economic Role and Benefits

The global market for 2-butoxyethanol was valued at approximately $1.2 billion in 2024, with projections estimating growth to $1.85 billion by 2033, reflecting its role in solvent-dependent industries such as coatings, products, and inks. This expansion is driven by demand for versatile solvents that enhance stability and performance, supporting downstream manufacturing sectors with reliable supply chains for chemical intermediates derived from and n-butanol. In industrial applications, 2-butoxyethanol provides superior for both water-soluble and oil-based systems, enabling the creation of concentrated formulations that require lower overall volumes compared to less efficient alternatives, thereby reducing and transportation costs. Its compatibility with diverse resins and improves product efficacy, such as faster drying times in lacquers and enhanced grease removal in cleaners, which translates to higher productivity in and operations without necessitating higher concentrations that could elevate expenses. These attributes position it as a cost-effective option over traditional solvents, which often demand greater quantities or additional additives to achieve equivalent dissolution power. The chemical's high production scale underpins in petrochemical synthesis and facilities, with its widespread adoption in household and industrial products sustaining ancillary jobs in distribution and across global supply networks. At regulated exposure levels, these gains from optimized outweigh potential handling costs, affirming its economic viability in compliant industrial practices.

References

  1. https://pubchem.ncbi.nlm.nih.gov/compound/2-Butoxyethanol
  2. http://www.osha.gov/chemicaldata/130
  3. https://www.ncbi.nlm.nih.gov/books/NBK594627/table/ch3.tab3/?report=objectonly
  4. https://www.atsdr.cdc.gov/toxprofiles/tp118.pdf
  5. https://www.ncbi.nlm.nih.gov/books/n/tp2but2butoxacetate/ch4/
  6. https://www.inchem.org/documents/cicads/cicads/cicad10.htm
  7. https://wwwn.cdc.gov/TSP/PHS/PHS.aspx?phsid=345&toxid=61
  8. https://www.atsdr.cdc.gov/toxprofiles/tp118-c4.pdf
  9. https://www.cdc.gov/niosh/idlh/111762.html
  10. https://www.sigmaaldrich.com/US/en/sds/sigald/537551
  11. https://www.sigmaaldrich.com/US/en/product/sigald/537551
  12. https://publications.iarc.who.int/_publications/media/download/4768/f66e32085783e69ddca49487aee594e857c4cd2f.pdf
  13. https://www.sciencedirect.com/topics/chemistry/2-butoxyethanol
  14. https://centro-chem.com/raw-material/butylglycol-bg/
  15. https://www.sigmaaldrich.com/TW/en/sds/mm/bx1715
  16. https://www.ncbi.nlm.nih.gov/books/NBK594625/
  17. https://www.ncbi.nlm.nih.gov/books/NBK594632/
  18. https://patents.google.com/patent/RU2758851C1/en
  19. https://www.industrialchemicals.gov.au/sites/default/files/PEC6-2-Butoxyethanol-in-cleaning-products.pdf
  20. https://taylorandfrancis.com/knowledge/Engineering_and_technology/Chemical_engineering/2-butoxyethanol/
  21. https://www.chemicalsafetyfacts.org/chemicals/butoxyethanol-2-butoxyethanol/
  22. https://www.specialchem.com/coatings/product/basf-butyl-glycol
  23. http://www.chemicalsafetyfacts.org/chemicals/butoxyethanol-2-butoxyethanol/
  24. https://consolidated-chemical.com/product/butyl-cellosolve-2-butoxyethanol/
  25. https://www.dir.ca.gov/dosh/DoshReg/5155-Meetings/2-butoxyethanol-and-2-butoxyethyl-acetate.pdf
  26. https://www.sciencedirect.com/science/article/pii/S2214181216300192
  27. https://pubs.acs.org/doi/10.1021/acsomega.1c01779
  28. https://onepetro.org/books/book/4/chapter/10893229/Cleaning-of-Pipelines-and-Facilities
  29. https://data.epo.org/publication-server/rest/v1.0/publication-dates/20180822/patents/EP3363876NWA1/document.pdf
  30. https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1006B54.TXT
  31. https://www.tceq.texas.gov/downloads/toxicology/dsd/final/butoxyethanol-2.pdf
  32. https://nj.gov/health/eoh/rtkweb/documents/fs/0275.pdf
  33. https://pubmed.ncbi.nlm.nih.gov/8104009/
  34. https://ntp.niehs.nih.gov/sites/default/files/ntp/htdocs/lt_rpts/tr484.pdf
  35. https://publications.iarc.who.int/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Formaldehyde-2-Butoxyethanol-And-1--Em-Tert-Em--Butoxypropan-2-ol-2006
  36. https://www.cir-safety.org/sites/default/files/Butoxyethanol.pdf
  37. https://www.sciencedirect.com/science/article/abs/pii/S0041008X84712294
  38. https://pubmed.ncbi.nlm.nih.gov/7974497/
  39. https://www.atsdr.cdc.gov/toxprofiles/tp118-c5.pdf
  40. https://hpvchemicals.oecd.org/ui/handler.axd?id=0fbae729-1207-4829-b0e8-f1f1b1f7a8d4
  41. https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/psl2-lsp2/2_butoxyethanol/2_butoxyethanol-eng.pdf
  42. https://www.ncbi.nlm.nih.gov/books/n/tp2but2butoxacetate/ch5/
  43. https://jmnspecialties.com/downloads/sds/3147-2-butoxyethanol-sds-docx/file
  44. https://www.osha.gov/chemicaldata/130
  45. https://www.cdc.gov/niosh/npg/npgd0070.html
  46. https://cdxapps.epa.gov/oms-substance-registry-services/substance-details/27847
  47. https://www.federalregister.gov/documents/2004/11/29/04-26071/list-of-hazardous-air-pollutants-petition-process-lesser-quantity-designations-source-category-list
  48. https://wwwapps.emnrd.nm.gov/OCD/OCDPermitting/Report/Fracking/FrackingFluidDisclosure.aspx?PermitID=202%2C146%2C237%2C81%2C254%2C201%2C80%2C223
  49. https://www.epa.gov/sites/default/files/2016-12/documents/hfdwa_executive_summary.pdf
  50. https://laws-lois.justice.gc.ca/eng/regulations/SOR-2006-347/page-2.html
  51. https://laws-lois.justice.gc.ca/eng/regulations/SOR-2025-36/FullText.html
  52. https://gazette.gc.ca/rp-pr/p2/2025/2025-03-12/html/sor-dors36-eng.html
  53. https://pollution-waste.canada.ca/environmental-protection-registry/regulations/view?Id=2184
  54. https://publications.gc.ca/collections/collection_2016/eccc/En84-136-2005-eng.pdf
  55. https://www.tga.gov.au/resources/publication/scheduling-decisions-interim/publication-interim-decisions-proposing-amend-or-not-amend-current-poisons-standard-september-2018/21-2-butoxyethanol
  56. https://www.cirs-group.com/en/chemicals/the-european-union-added-39-entries-into-the-annex-vi-to-the-clp-regulation
  57. https://marketintelo.com/report/2-butoxyethanol-market
  58. https://www.cognitivemarketresearch.com/2-butoxyethanol-market-report
  59. https://elsapainternational.com/en/news/28/Benefits-of-Butyl-Glycol
  60. https://www.linkedin.com/pulse/glycol-ethers-vs-traditional-solvents-comparative-analysis-lucy-liu-d8izc
  61. https://www.globalinforesearch.com/reports/2834914/2-butoxyethanol
Add your contribution
Related Hubs
User Avatar
No comments yet.