Peracetic acid

Peracetic acid
Peroxyacetic acid	Peroxyacetic acid
Names
	IUPAC name Ethaneperoxoic acid
	Other names Peroxyacetic acid; Acetic peroxide; Acetyl hydroperoxide; Proxitane
Identifiers
CAS Number	79-21-0 ;
3D model (JSmol)	Interactive image;
Abbreviations	PAA
ChEMBL	ChEMBL444965 ;
ChemSpider	6336 ;
ECHA InfoCard	100.001.079
KEGG	D03467 ;
PubChem CID	6585;
RTECS number	SD8750000;
UNII	I6KPI2E1HD ;
CompTox Dashboard (EPA)	DTXSID1025853 ;
	InChI InChI=1S/C2H4O3/c1-2(3)5-4/h4H,1H3 Key: KFSLWBXXFJQRDL-UHFFFAOYSA-N ; InChI=1/C2H4O3/c1-2(3)5-4/h4H,1H3 Key: KFSLWBXXFJQRDL-UHFFFAOYAD;
	SMILES CC(=O)OO;
Properties
Chemical formula	C2H4O3
Molar mass	76.05
Appearance	Colorless liquid
Density	1.0375 g/mL
Melting point	0 °C
Boiling point	25 °C (1.6 kPa)
Acidity (pKa)	8.2
Refractive index (nD)	1.3974 (589 nm, 20 °C)
Viscosity	3.280 cP
Hazards
NFPA 704 (fire diamond)	3 2 2 OX
Flash point	40.5 °C
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) 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 much weaker acid than the parent acetic acid, with a pK_a of 8.2.

Production

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

H₂O₂ + CH₃CO₂H ⇌ CH₃CO₃H + H₂O

As an alternative, acetyl chloride and acetic anhydride can be used to generate products with lower water content.

Peracetic acid is produced by continuously feeding acetic acid and hydrogen peroxide into an aqueous reaction medium containing a sulfuric acid catalyst. The reaction is allowed to continue for up to ten days in order to achieve high yields of product according to the following equation.^[2]

Peracetic acid is always sold in solution with acetic acid and hydrogen peroxide to maintain the stability of the chemical. The concentration of the acid as the active ingredient can vary, and usually depends on its application. Additional methods of preparation involve the oxidation of acetaldehyde or, as an alternative, as an end-product of the reaction of acetic anhydride, hydrogen peroxide, and sulfuric acid. Another method involves the reaction of tetraacetylethylenediamine (TAED) in the presence of an alkaline hydrogen peroxide solution.^[2] PAA is also formed naturally in the environment through a series of photochemical reactions involving formaldehyde and photo-oxidant radicals.^[3]

Uses

Synthesis of other compounds

The main use of peracetic acid is for the industrial synthesis of epoxides. It transfers an oxygen atom to double bonds, e.g. in ethene and propene, to form epoxides and alcohols. It can also be used in producing synthetic glycerol from propene, and is used in nylon manufacturing.^[4]

Antimicrobial agent

Peracetic acid is an ideal antimicrobial agent due to its high oxidizing potential. It is broadly effective against microorganisms and is not deactivated by catalase and peroxidase, the enzymes that break down hydrogen peroxide. It also breaks down in food to safe and environmentally friendly residues (acetic acid and hydrogen peroxide), and therefore can be used in non-rinse applications. It can be used over a wide temperature range (0–40 °C), over a wide pH range (3.0–7.5), in clean-in-place (CIP) processes, in hard water conditions, and is not affected by protein residues.

Mechanism of action

Peracetic acid kills microorganisms by oxidation and subsequent disruption of their cell membrane, via the hydroxyl radical (HO·). As diffusion is slower than the half-life of the radical, it will react with any oxidizable compound in its vicinity. It can damage virtually all types of macromolecules associated with a microorganism: carbohydrates, nucleic acids (mutations), lipids (lipid peroxidation), and amino acids (e.g., conversion of Phe to m-Tyr and o-Tyr). This ultimately leads to cell lysis and true microbial death.

Application

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.^[5] 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.

Bleaching agent

Peracetic acid can be used as a bleaching agent especially for Kraft pulp. It is used at weakly acidic pH and relatively low temperature. It is a relative efficient and selective bleaching agent, and it is often used as an alternative to chlorine dioxide and elemental chlorine in totally chlorine-free bleaching sequences (TCF). It is, however, relatively expensive, and is difficult to store due to its high reactivity. This has limited its use.

Fowl sanitizer

Peracetic acid is extremely effective for sanitizing fowl carcasses without affecting the skin or the flesh of the bird carcass by applying direct to the meat. In particular, peracetic acid is applied to a fowl that has been killed, plucked, and eviscerated by contacting the fowl with an aqueous peracetic acid solution and maintaining that contact to a time sufficient to sanitize the fowl.

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.

References

^ ^a ^b ^c ^d ^e Elvers, B. et al. (ed.) Ullmann's Encyclopedia of Industrial Chemistry, 5th ed. Vol. A19, Wiley, p. 206
^ ^a ^b United States Department of Agriculture. Agriculture Marketing Service Peracetic acid. (PDF document). URL accessed on 11 November 2006.
^ U.S. National Library of Medicine. Hazardous Substances Data Bank. URL accessed on 11 November 2006.
^ KEMI – Information on Substances. Peracetic Acid. URL accessed on 11 November 2006.
^ U.S. Environmental Protection Agency. Hydrogen Peroxide and Peroxyacetic Acid. URL accessed on 11 November 2006.
^ 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.
^ E.C. Marquand; et al. (2007). "Asthma Caused by Peracetic Acid-Hydrogen Peroxide Mixture". J. Occup. Health. 49 (2): 155–158. {{cite journal}}: Explicit use of et al. in: |author= (help)
^ 29 CFR 1910.1000 Table Z-1
^ US – Occupational Safety and Health Act (1970), sec. 5

[u1-1] Elvers, B. et al. (ed.) Ullmann's Encyclopedia of Industrial Chemistry, 5th ed. Vol. A19, Wiley, p. 206

[AMS-2] United States Department of Agriculture. Agriculture Marketing Service Peracetic acid. (PDF document). URL accessed on 11 November 2006.

[USLib-3] U.S. National Library of Medicine. Hazardous Substances Data Bank. URL accessed on 11 November 2006.

[KEMI-4] KEMI – Information on Substances. Peracetic Acid. URL accessed on 11 November 2006.

[USEPA-5] U.S. Environmental Protection Agency. Hydrogen Peroxide and Peroxyacetic Acid. URL accessed on 11 November 2006.

[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. {{cite journal}}: Explicit use of et al. in: |author= (help)

[8] 29 CFR 1910.1000 Table Z-1

[9] US – Occupational Safety and Health Act (1970), sec. 5

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