2-Butoxyethanol

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 [3] and can be acutely toxic but animal studies did not find it to be mutagenic, and no studies suggest it is a human carcinogen.[4] A study of 13 classroom air contaminants conducted in Portugal reported a statistically significant association with increased rates of nasal obstruction, the study also reported a positive association below the level of statistical significance with a higher risk of obese asthma and increased child BMI.[5]

2-Butoxyethanol

Names
Preferred IUPAC name 2-Butoxyethan-1-ol
Other names 2-Butoxyethanol Butyl cellosolve Butyl glycol Butyl monoether glycol EGBE (ethylene glycol monobutyl ether) Dowanol EB Bane-Clene Eastman EB solvent BH-33 industrial cleaner Solvaset 2-BE EGMBE Butyl oxitol Ektasolve Jeffersol EB
Identifiers
CAS Number	111-76-2^Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:63921^N
ChEMBL	ChEMBL284588
ChemSpider	13836399^N
ECHA InfoCard	100.003.550
EC Number	203-905-0
PubChem CID	8133
RTECS number	KJ8575000
UNII	I0P9XEZ9WV^Y
UN number	1993, 2810, 2369
CompTox Dashboard (EPA)	DTXSID1024097
InChI 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
SMILES OCCOCCCC
Properties
Chemical formula	C6H14O2
Molar mass	118.176 g·mol^−1
Appearance	Clear, colorless liquid
Density	0.90 g/cm^3, liquid
Melting point	−77 °C (−107 °F; 196 K)
Boiling point	171 °C (340 °F; 444 K)
Solubility in water	Miscible (and in most organic solvents)
Vapor pressure	0.8 mmHg[1]
Acidity (pKa)	high pKa for -OH group
Viscosity	2.9 cP at 25 °C (77 °F)
Hazards
Safety data sheet	MSDS by Mallinckrodt Baker
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H227, H302, H311, H315, H319, H330, H336, H361, H370, H372
GHS precautionary statements	P201, P202, P210, P260, P261, P264, P270, P271, P280, P281, P284, P301+312, P302+352, P304+340, P305+351+338, P307+311, P308+313, P310, P312, P314, P320, P321, P322, P330, P332+313
NFPA 704 (fire diamond)	2 2 0
Flash point	67 °C (153 °F; 340 K)
Autoignition temperature	245 °C (473 °F; 518 K)
Explosive limits	1.1–12.7%[1]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	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)[2]
LC50 (median concentration)	450 ppm (rat, 4 hr) 700 ppm (mouse, 7 hr)[2]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 50 ppm (240 mg/m^3) [skin][1]
REL (Recommended)	TWA 5 ppm (24 mg/m^3) [skin][1]
IDLH (Immediate danger)	700 ppm[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 ^YN ?)
Infobox references

Production

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.[6] 2-butoxyethanol can be obtained in the laboratory by performing a ring opening of 2-propyl-1,3-dioxolane with boron trichloride.[7] It is often produced industrially by combining ethylene glycol and butyraldehyde in a Parr reactor with palladium on carbon.[8]

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[9] and 18% for metal cleaners and household cleaners.[10] In the US, it is considered a High Production Volume Chemical because greater than 100 million pounds of this chemical is produced per year.[10]

Uses

2-Butoxyethanol is a glycol ether with modest surfactant properties (and it can be used as a mutual solvent). In use since the 1930s, glycol ethers are solvents that dissolve both water-soluble and hydrophobic substances. Glycol ethers consist of two components, an alcohol and ether. According to the nature of alcohol, molecules of this class can be divided into two groups: E series and P series which correspond to ethylene and propylene respectively. Glycol ethers are selected for specific purposes, such as solubility, inflammability, and volatility.[11]

Commercial uses

2-Butoxyethanol is a solvent for paints and surface coatings, as well as cleaning products and inks.[9][12] 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 cleaners, liquid soaps, cosmetics, dry cleaning solutions, lacquers, varnishes, herbicides, latex paints, enamels, printing paste, and 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 non-polar and polar ends, 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.[13]

In the petroleum industry

2-Butoxyethanol is commonly produced for the oil industry because of its surfactant properties.[14]

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[10] 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.[10] As a surfactant, 2-butoxyethanol adsorbs at the oil-water interface of the fracture.[15] The compound is also used to facilitate the release of the gas by preventing congealing.[10] It is also used as a crude oil-water coupling solvent for more general oil well workovers.[10] Because of its surfactant properties, it is a major constituent (30–60% w/w) in the oil spill dispersant Corexit 9527,[16] which was widely used in the aftermath of the 2010 Deepwater Horizon oil spill.[13]

Safety

2-Butoxyethanol has a low acute toxicity, with LD₅₀ of 2.5 g/kg in rats.[9] 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.[17] American Conference of Governmental Industrial Hygienists (ACGIH) reports that 2-butoxyethanol is carcinogenic in rodents.[18] These rodent tests may not directly translate to carcinogenicity in humans, as the observed mechanism of cancer involves the rodents' forestomach, which humans lack.[19] OSHA does not regulate 2-butoxyethanol as a carcinogen.[20] 2-butoxyethanol has not been shown to penetrate shale rock in a study conducted by Manz.[21]

Disposal and degradation

2-Butoxyethanol can be disposed of by incineration. It was shown that disposal occurs faster in the presence of semiconductor particles.[6] 2-Butoxyethanol usually decomposes in the presence of air within a few days by reacting with oxygen radicals.[22] It has not been identified as a major environmental contaminant, nor is it known to bio-accumulate.[23] 2-Butoxyethanol biodegrades in soils and water, with a half life of 1–4 weeks in aquatic environments.[13]

Human exposure

2-butoxyethanol most commonly enters the human body system through dermal absorption, inhalation, or oral consumption of the chemical.[6] 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.[24][25] 2-Butoxyethanol and its metabolites fall to undetectable levels in urine after about 30 hours in human males.[26]

Animal studies

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.[27] 2-Butoxyethanol is metabolized in mammals by the enzyme alcohol dehydrogenase.[26]

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.[28]

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.[27]

Regulation in Canada

Environment and Health Canada recommended that 2-butoxyethanol be added to Schedule 1 of the Canadian Environmental Protection Act, 1999 (CEPA).[29] 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.[30]

Regulation in the US

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,[31] and in California employers are required to inform employees when they are working with it.[32]

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",[13] 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".[33] After it was deleted 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.[34][35] The safety of products containing 2-butoxyethanol as normally used is defended by the industry trade groups the American Chemistry Council[35] and the Soap and Detergent Association.

References

1. NIOSH Pocket Guide to Chemical Hazards. "#0070". National Institute for Occupational Safety and Health (NIOSH).
2. "2-Butoxyethanol". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
3. "TOXNET HAS MOVED". www.nlm.nih.gov. Retrieved 2020-01-24.
4. "Public Health Statement for 2-Butoxyethanol and 2-Butoxyethanol Acetate". Agency for Toxic Substances and Disease Registry, Center for Disease Control. August 1998. Retrieved 16 February 2020.
5. Paciência, Inês; Cavaleiro Rufo, João; Silva, Diana; Martins, Carla; Mendes, Francisca; Farraia, Mariana; Delgado, Luís; De Oliveira Fernandes, Eduardo; Padrão, Patrícia; Moreira, Pedro; Severo, Milton; Barros, Henrique; Moreira, André (2019). "Exposure to indoor endocrine-disrupting chemicals and childhood asthma and obesity". Allergy. 74 (7): 1277–1291. doi:10.1111/all.13740. PMID 30740706.
6. Harris O.; et al. (August 1998). Toxicological Profile for 2-Butoxyethanol and 2-butoxyethanol acetate. U.S. Dept of Health and Human Services.
7. Bonner, Trevor (1981). "Opening of cyclic acetals by trichloro-, dichloro-, and tribromo-borane". Journal of the Chemical Society, Perkin Transactions 1: 1807–1810. doi:10.1039/p19810001807.
8. Tulchinsky, Michael (2014). "Poly ethers and process for making them". Cite journal requires |journal= (help)
9. Siegfried Rebsdat, Dieter Mayer "Ethylene Glycol" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000.doi:10.1002/14356007.a10_101.
10. "Ethylene Glycol Mono-N-Butyl Ether". National Library of Medicine. Retrieved 2014-03-26.
11. Elskamp, Carl J. "2-Butoxyethanol (Butyl Cellosolve) & 2-Butoxyethyl Acetate (Butyl Cellosolve Acetate)". United States Department of Labor.
12. "Sharpie Frequently Asked Questions". sharpie.com. Archived from the original on 26 May 2015. Retrieved 30 June 2015.
13. Dickey, Robert; W. Dickhoff. "Assessment of the potential impact of COREXIT® oil dispersants on seafood safety" (PDF). Dispersants and Seafood Safety. Retrieved 2014-03-26.
14. Rogers, J (2015). "A Framework for Identifying Organic Compounds of Concern in Hydraulic Fracturing Fluids Based on Their Mobility and Persistence in Groundwater". Environmental Science and Technology Letters. 2 (6): 158–164. doi:10.1021/acs.estlett.5b00090.
15. Barati, Reza (2014). "A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells". Journal of Applied Polymer Science. 131 (16): n/a. doi:10.1002/app.40735.
16. "SAFETY DATA SHEET - PRODUCT: COREXIT® EC9527A" (PDF). Nalco Environmental Solutions LLC. 1 March 2012. Retrieved 30 April 2014.
17. "Toxicology and Carcinogenesis Studies 2-Butoxyethanol (CAS NO. 111-76-2) in F344/N Rats and B6C3F1 Mice (Inhalation Studies)". National Toxicology Program: Department of Health and Human Services. USA.gov. Archived from the original on 2010-05-28. Retrieved 4 June 2010.
18. Air Foam HD Material Data Safety Sheet. Product Safety. AquaClear, Inc. Retrieved 4 June 2010.
19. Gift, J. S. (2005). "U.S. EPA's IRIS assessment of 2-Butoxyethanol: the relationship of noncancer to cancer effects". Toxicol. Lett. 156 (1): 163–178. doi:10.1016/j.toxlet.2003.08.014. PMID 15705494.
20. "Chemical Sampling Information | 2-Butoxyethanol". Occupational Safety & Health Administration.
21. Manz, K (2016). "Adsorption of hydraulic fracturing fluid components 2-butoxyethanol and furfural onto granular activated carbon and shale rock". Chemosphere. 164: 585–592. Bibcode:2016Chmsp.164..585M. doi:10.1016/j.chemosphere.2016.09.010. PMID 27632795.
22. Hullar, T.; Anastasio, C. Yields of hydrogen peroxide from the reaction of hydroxyl radical with organic compounds in solution and ice. Atmospheric Chemistry and Physics, 11, 7209.
23. "ATSDR - ToxFAQs™: 2-Butoxyethanol and 2-Butoxyethanol Acetate". cdc.gov. Retrieved 30 June 2015.
24. 2009 TLVs and BEIs, American Conference of Industrial Hygienists, Cincinnati, Ohio, 2009, p.101.
25. R. Baselt (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, CA: Biomedical Publications. pp. 208–210.
26. Franks, S. J.; Spendiff, M. K.; Cocker, J.; Loizou, G. D. (2006). "Physiologically based pharmacokinetic modelling of human exposure to 2-butoxyethanol". Toxicol. Lett. 162 (2–3): 164–173. doi:10.1016/j.toxlet.2005.09.012. PMID 16246510.
27. Wess, Ms. J., Dr. H. Ahlers, and Dr. S Dobson. "Concise International Chemical Assessment Document 10: 2-Butoxyethanol." World Health Organization, n.d. Web. <http://www.who.int/ipcs/publications/cicad/cicad_10_revised.pdf>
28. United States of America. Agency for Toxic Substances and Disease Registry. Department of Health and Human Services. Toxicological Profile for 2-Butoxyethanol and 2-Butoxyethanol Acetate. By Olivia Harris, Sharon Wilbur, Julia George, and Carol Eisenmann. Atlanta: n.p., 1998. Agency for Toxic Substances and Disease Registry. Web. <http://www.atsdr.cdc.gov/toxprofiles/tp118.pdf>
29. "Current Use Patterns in Canada, Toxicology Profiles of Alternatives, and the Feasibility of Performing an Exposure Assessment Survey". Environment Canada. 2017-03-12. Retrieved 15 February 2011.
30. "Regulations Amending the 2-Butoxyethanol Regulations". Canada Gazette. Canadian Department of Public Works and Government Services. 23 April 2014. Retrieved 30 April 2014.
31. "California Code of Regulations, Title 8, Section 339. The Hazardous Substances List". State of California Department of Labor Relations. Archived from the original on 5 May 2008. Retrieved 2008-04-21.
32. "Glycol Ethers Fact Sheet". California Hazard Evaluation and Information Service. Archived from the original on 18 August 2007. Retrieved 29 October 2007.
33. CFR Title 21 - Food and Drugs - URL: http://www.fda.gov (2004). CFR Title: 21 CFR Part Section: 173.315
34. "List of Hazardous Air Pollutants, Petition Process, Lesser Quantity Designations, Source Category List; Petition To Delist of Ethylene Glycol Monobutyl Ether". U.S. Environmental Protection Agency. 2004-11-29. Retrieved 23 February 2008.
35. "EGBE: A World of Solutions 2000" (PDF). July 2000. Archived from the original (PDF) on 3 October 2006. Retrieved 30 April 2014.

External links

• International Chemical Safety Card 0059
• NIOSH Pocket Guide to Chemical Hazards
• Inchem SIDS dossier
• Eastman EB solvent info
• ToxFAQs™ for 2-Butoxyethanol and 2-Butoxyethanol Acetate from the Centers for Disease Control