Peracetic acid

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Peracetic acid
IUPAC name

Ethaneperoxoic acid

Other names

Peroxyacetic acid
Acetic peroxide
Acetyl hydroperoxide
Proxitane

Identifiers
Abbreviations PAA
CAS number 79-21-0 YesY
PubChem 6585
ChemSpider 6336 YesY
UNII I6KPI2E1HD YesY
KEGG D03467 YesY
ChEMBL CHEMBL444965 YesY
RTECS number SD8750000
ATCvet code QG51AD03
Jmol-3D images Image 1
Properties
Molecular formula C2H4O3
Molar mass 76.05
Appearance Colorless liquid
Density 1.0375 g/mL
Melting point 0 °C[1]
Boiling point 25 °C (1.6 kPa)[1]
Acidity (pKa) 8.2
Refractive index (nD) 1.3974 (589 nm, 20 °C)[1]
Viscosity 3.280 cP
Hazards
EU classification Oxidant (O)
Corrosive (C)
Dangerous for the environment (N)
R-phrases R8 R5 R11 R25 R34
S-phrases (S1/2) S3/7 S14 S36/37/39 S45 S61
NFPA 704
2
3
2
OX
Flash point 40.5 °C; 104.9 °F; 313.6 K
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Peracetic acid (also known as peroxyacetic acid, or PAA), is an organic compound with the formula CH3CO3H. This organic peroxide is a colorless liquid with a characteristic acrid odor reminiscent of acetic acid. It can be highly corrosive.

Peracetic acid is a weaker acid than the parent acetic acid, with a pKa of 8.2.[1]

Production

Peracetic acid is produced industrially by the autoxidation of acetaldehyde:[1]

O2 + CH3CHO → CH3CO3H

It forms upon treatment of acetic acid with hydrogen peroxide, the equilibrium constant being 0.37 at room temperature:

H2O2 + CH3CO2H is in equilibrium with CH3CO3H + H2O

As an alternative, acetyl chloride and acetic anhydride can be used to generate a solution of the acid with lower water content.

Peracetic acid is generated in situ by some laundry detergents. This route involves the reaction of tetraacetylethylenediamine (TAED) in the presence of an alkaline hydrogen peroxide solution. The peracetic acid is a more effective bleaching agent than hydrogen peroxide itself.[1][2] PAA is also formed naturally in the environment through a series of photochemical reactions involving formaldehyde and photo-oxidant radicals.[3]

Peracetic acid is always sold in solution with acetic acid and hydrogen peroxide to maintain the stability of the peracid. The concentration of the acid as the active ingredient can vary.

Uses

The United States Environmental Protection Agency first registered peracetic acid as an antimicrobial in 1985 for indoor use on hard surfaces. Use sites include agricultural premises, food establishments, medical facilities, and home bathrooms. Peracetic acid is also registered for use in dairy/cheese processing plants, on food processing equipment, and in pasteurizers in breweries, wineries, and beverage plants.[4] It is also applied for the disinfection of medical supplies, to prevent bio film formation in pulp industries, and as a water purifier and disinfectant. Peracetic acid can be used as a cooling tower water disinfect, where it prevents bio film formation and effectively controls Legionella bacteria. A trade name for peracetic acid as an antimicrobial is Nu-Cidex.[5]

Epoxidation

Although less active than more acidic peracids (e.g., MCPBA), peracetic acid in various forms is used for the epoxidation of various alkenes. Useful application are for unsaturated fats, synthetic and natural rubbers, and some natural products such as pinene. A variety of factors affect the amount of free acid or sulfuric acid (used to prepare the peracid in the first place).[1]

Niche uses

Peracetic acid will oxidize many metals, and is used for cleaning or creating a patina for artistic or protective purposes.

Safety

Peracetic acid is a strong oxidizing agent (E = 1.762 V vs Ag/AgCl)[6] and a primary irritant. Exposure to peracetic acid can cause irritation to the skin, eyes and respiratory system and higher or long-term exposure can cause permanent lung damage. In addition, there have been cases of occupational asthma caused by peracetic acid.[7] There is no US-OSHA permissible exposure limit for peracetic acid, but this does not mean the compound is harmless. In 2010, the US-EPA published Acute Exposure Guidelines (AEGL) for peracetic acid.

eight-hour TWA AEGL Definition mg/m3 ppm
1 The concentration at which the general population will experience transient and reversible problems, such as notable discomfort, irritation, or certain asymptomatic non-sensory effects. 0.52 0.17
2 The concentration that results in irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape. 1.6 0.52
3 The concentration that results in life-threatening health effects or death 4.1 1.3

In comparison, the OSHA PEL for hydrogen peroxide (8 hour TWA) is 1.0 ppm.[8] Peracetic acid has found widespread use in healthcare, food processing, and water treatment because of its broad antimicrobial properties. In order for employers to comply with the General Duty Clause[9] to provide a safe work environment, it is recommended that facilities using peracetic acid solution employ continuous monitors to provide an alert to employees if the concentration exceeds safe levels. This monitor is designed and installed so that it can automatically turn on additional ventilation as needed.

Concentrated peroxyacetic acid, an organic peroxide, explodes at 110 °C.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Herbert Klenk, Peter H. Götz, Rainer Siegmeier, Wilfried Mayr (2005), "Peroxy Compounds, Organic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a19_199 
  2. ↑ United States Department of Agriculture. Agriculture Marketing Service Peracetic acid. (PDF document). URL accessed on 11 November 2006.
  3. ↑ U.S. National Library of Medicine. Hazardous Substances Data Bank. URL accessed on 11 November 2006.
  4. ↑ U.S. Environmental Protection Agency. Hydrogen Peroxide and Peroxyacetic Acid. URL accessed on 11 November 2006.
  5. ↑ Lynam, P. A.; Babb, J. R.; Fraise, A. P. (1995). "Comparison of the mycobactericidal activity of 2% alkaline glutaraldehyde and 'Nu-Cidex' (0.35% peracetic acid)". The Journal of hospital infection 30 (3): 237–240. PMID 8522783. 
  6. ↑ Awad, Mohamed Ismail; Denggerile, Ao; Ohsaka, Takeo (2004). "Electroreduction of Peroxyacetic Acid at Gold Electrode in Aqueous Media". Journal of the Electrochemical Society 151: E358. doi:10.1149/1.1812733. 
  7. ↑ E.C. Marquand et al (2007). "Asthma Caused by Peracetic Acid-Hydrogen Peroxide Mixture". J. Occup. Health 49 (2): 155–158. 
  8. ↑ 29 CFR 1910.1000 Table Z-1
  9. ↑ US – Occupational Safety and Health Act (1970), sec. 5
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