Chlorine-releasing compounds

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Chlorine-releasing compounds
Clorox Bleach products.jpg
One brand of chlorine based bleach
Clinical data
Other namesChlorine-releasing disinfectants, [1] chlorine base compounds, chlorine-releasing bleach, chlorine based bleach
Drug class Disinfectant
ATC code

Chlorine-releasing compounds, also known as chlorine base compounds, is jargon to describe certain chlorine-containing substances that are used as disinfectants and bleaches. They include the following chemicals: sodium hypochlorite (active agent in bleach), chloramine, halazone, and sodium dichloroisocyanurate. [2] They are widely used to disinfect water and medical equipment, and surface areas as well as bleaching materials such as cloth. The presence of organic matter can make them less effective as disinfectants. [3] They come as a liquid solution, or as a powder that is mixed with water before use. [2]

Contents

Side effects if contact occurs may include skin irritation and chemical burns to the eye. [2] They may also cause corrosion and therefore may require being rinsed off. [3] Specific compounds in this family include sodium hypochlorite, monochloramine, halazone, chlorine dioxide, and sodium dichloroisocyanurate. [2] [4] They are effective against a wide variety of microorganisms including bacterial spores. [4] [3]

Chlorine-releasing compounds first came into use as bleaching agents around 1785, [5] and as disinfectants in 1915. [6] They are on the World Health Organization's List of Essential Medicines. [7] They are used extensively in both the medical and the food industry. [4]

Uses

Chlorine-based compounds are usually handled in water solutions, powders, or tablets, that are mixed with water before use. [2] They may have to be rinsed off after application to avoid corrosion of metals and degradation of organic materials. [3]

Disinfectants

Chlorine-based compounds are effective against a wide variety of microorganisms including bacterial spores. [4] [3] They are listed by the World Health Organization as essential medicines in any health system.

The presence of other organic matter in the place of application can make these disinfectants less effective, by consuming some of the released chlorine. [3]

Whitening agents

Chlorine-based bleaches have been used since the late 18th century to whiten cotton and linen clothes, removing either the natural fiber color or stains of sweat or other organic residues. They are still used in households for laundry and to remove organic stains (such as mildew) on surfaces.

Colors of natural materials typically arise from organic pigments, such as beta carotene. Chlorine-based compounds work by breaking the chemical bonds that make up the pigment's chromophore. This changes the molecule into a different substance that either does not contain a chromophore, or contains a chromophore that does not absorb visible light.

Industrially, chlorine-based bleaches are used in a wide variety of processes, including bleaching of wood pulp.

Safety

Chlorine-releasing products present significant risks. It is estimated that, in 2002, there were about 3300 accidents needing hospital treatment caused by liquid bleach in British homes, and about 160 due to bleaching powder. [8]

Chemical burns

Chlorine releasing solutions, such as liquid bleach and solutions of bleaching powder, can burn the skin and cause eye damage, [2] especially when used in concentrated forms. As recognized by the NFPA, however, only solutions containing more than 40% sodium hypochlorite by weight are considered hazardous oxidizers. Solutions less than 40% are classified as a moderate oxidizing hazard (NFPA 430, 2000).

Release of chlorine gas

Mixing a hypochlorite bleach with an acid can liberate chlorine gas.

Chlorine is a respiratory irritant that attacks mucous membranes and burns the skin. As little as 3.53 ppm can be detected as an odor, and 1000 ppm is likely to be fatal after a few deep breaths. Exposure to chlorine has been limited to 0.5 ppm (8-hour time-weighted average—38-hour week) by the U.S. OSHA. [9] Due to transport and handling safety concerns, the use of sodium hypochlorite is preferred over chlorine gas in water treatment. [10]

Reaction with other products

Chlorine releasing compounds can react with other common household chemicals like vinegar or ammonia to produce toxic gases.

Mixing an acid cleaner with a hypochlorite bleach can cause toxic chlorine gas to be released. The hypochlorite anion and chlorine are in equilibrium in water; the position of the equilibrium is pH dependent and low pH (acidic) favors chlorine, [11]

Cl2 + H2O ⇌ 2H+ + Cl− + ClO−

A hypochlorite bleach can react violently with hydrogen peroxide and produce oxygen gas:

H2O2(aq) + NaOCl (aq) → NaCl (aq) + H2O(l) + O2(g)

A 2008 study indicated that sodium hypochlorite and organic chemicals (e.g., surfactants, fragrances) contained in several household cleaning products can react to generate chlorinated volatile organic compounds (VOCs). [12] These chlorinated compounds are emitted during cleaning applications, some of which are toxic and probable human carcinogens. The study showed that indoor air concentrations significantly increase (8–52 times for chloroform and 1–1170 times for carbon tetrachloride, respectively, above baseline quantities in the household) during the use of bleach containing products. The increase in chlorinated volatile organic compound concentrations was the lowest for plain bleach and the highest for the products in the form of "thick liquid and gel." The significant increases observed in indoor air concentrations of several chlorinated VOCs (especially carbon tetrachloride and chloroform) indicate that the bleach use may be a source that could be important in terms of inhalation exposure to these compounds. The authors suggested that using these cleaning products may significantly increase the cancer risk. [12]

The hypochlorites in liquid bleach and bleaching powder can react with ammonia to form a number of products, including monochloramine (NH
2Cl), then dichloramine (NHCl
2) and finally nitrogen trichloride (NCl
3). Similar reactions may occur with amines or related compounds and biological materials (such as urine). The result depends on the temperature, concentration, and how they are mixed. [13] [14] These compounds are very irritating to the eyes and lungs and are toxic above certain concentrations. Chronic exposure, for example, from the air at swimming pools where chlorine is used as the disinfectant, can lead to the development of atopic asthma. [15] Nitrogen trichloride is also a very sensitive explosive.

Corrosion

Chlorine releasing products may also cause corrosion of many materials and unintended bleaching of colored products. [3]

Neutralization

Sodium thiosulfate is an effective chlorine neutralizer. Rinsing with a 5 mg/L solution, followed by washing with soap and water, will remove chlorine odor from the hands. [16]

Main compounds

Specific compounds in this family include: [2] [4]

Mechanism of action

The activity and applications of chlorine-releasing compounds are diverse. Some have strong oxidizing character. Chlorine readily inserts itself into double bonds, including those of aromatic rings, creating chlorinated organic compounds. This accounts for its bleaching action, since many colored organic substances owe their color to compounds with such bonds.[ citation needed ]

The extensive reactivity of chlorine is also responsible for its broad antimicrobial effect, since it can destroy or denature many proteins and other chemicals that are essential for microbes' metabolism.

Free chlorine

The strength of chlorine-releasing solutions, as well as their dosage in uses like water chlorination and pool sanitization, is usually expressed as mass concentration of "free chlorine" or "available chlorine". It is the mass of chlorine gas (Cl2) that would yield the same oxidizing power as the product contained in (or applied to) a specific mass or volume of the liquid in question. The concentration can be expressed, for example, as grams per liter (g/L), milligrams per liter (mg/L), or parts per million (ppm). Thus, for example, "15 mg/L of available chlorine" means that the amount of product contained in one liter of the liquid has the same oxidizing power as 15 mg of chlorine. [24] [25]

The strength of commercial chlorine-releasing products may be instead specified as the concentration of the active ingredient, as mass or weight percent or grams per liter. In order to determine the free chlorine content of the product, one must take into account the oxidizing reactions that the ingredient may undergo in the application. For example, the label of a household bleach product may specify "5% sodium hypochlorite by weight." That would mean that 1 kilogram of the product contains 0.05 × 1000 g = 50 g of NaClO.

A typical oxidation reaction is the conversion of iodide I−
 to elemental iodine I
2. The relevant reactions are

NaClO + 2 H+
 + 2 I−
 → NaCl + H
2O + I
2
Cl
2 + 2 H+
 + 2 I−
 → 2 Cl−
 + H
2O + I
2

That is, one "molecule" of NaClO has the same oxidizing power as one molecule of Cl
2. Their molar masses are 74.44 g and 70.90 g, respectively. Therefore, 1 kilogram of the solution has 1000 × 0.05 × 70.90/74.44 = 47.62 g of "free chlorine".

In order to convert between mass ratios and mass per volume, one must take into account the density of the liquid in question. For chlorinated water, one can assume the density is the same as of pure water, about 1000 g/L (more precisely, about 997 g/L at 25 °C). For more concentrated solutions like liquid bleach, the density depends on the ingredients and their concentrations, and is usually obtained from tables. [24] When diluting a product, one must be aware that the volume of the diluted solution may not be the sum of the volumes of product and water. For example, one ml of 5.25 wt% NaClO bleach added to ten liters of water, will yield a NaClO concentration of about 5.76 mg/L, and 5.48 mg/L of free chlorine. [24]

History

Swedish chemist Scheele discovered chlorine in 1774, [26] and in 1785 French scientist Claude Louis Berthollet recognized that it could be used to bleach fabrics. [26] Berthollet also discovered potassium hypochlorite, which became the first commercial bleaching product, named Eau de Javel ("Javel water") after the borough in Paris where it was produced.

Scottish chemist and industrialist Charles Tennant proposed in 1798 a solution of calcium hypochlorite as an alternative for Javel water, and patented bleaching powder (a solid product containing calcium hypochlorite) in 1799. [26]

Around 1820, French chemist Labarraque discovered the disinfecting ability of hypochlorites, and popularized the use of the cheaper sodium hypochlorite solution (known as Eau de Labarraque, "Labarraque's water") throughout the world for that purpose. [27] His work greatly improved medical practice, public health, the sanitary conditions in hospitals, slaughterhouses, and all industries dealing with animal products—decades before Pasteur and others established the germ theory of disease. [28] In particular, it led to the nearly universal practice of chlorination of tap water to prevent the spread of diseases like typhoid fever and cholera. [29] [6]

In 1915, British chemist Henry Dakin, working at a field hospital in France during World War I, did an extensive study of compounds that could be used to disinfect wounds and prevent sepsis. He found that chloramine was optimal, but settled for a dilute sodium hypochlorite solution—still used today with the name of "Dakin's solution"—for reasons of cost and availability. [19] [17]

See also

Related Research Articles

<span class="mw-page-title-main">Chlorine</span> Chemical element, symbol Cl and atomic number 17

Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Pauling scale, behind only oxygen and fluorine.

<span class="mw-page-title-main">Sodium hypochlorite</span> Chemical compound (known in solution as bleach)

Sodium hypochlorite, commonly known in a dilute solution as (chlorine) bleach, is an alkaline inorganic chemical compound with the formula NaOCl, consisting of a sodium cation and a hypochlorite anion. It may also be viewed as the sodium salt of hypochlorous acid. The anhydrous compound is unstable and may decompose explosively. It can be crystallized as a pentahydrate NaOCl·5H
2O, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated.

<span class="mw-page-title-main">Water purification</span> Process of removing impurities from water

Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption, but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.

<span class="mw-page-title-main">Chlorine dioxide</span> Chemical compound

Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is usually handled as an aqueous solution. It is commonly used as a bleach. More recent developments have extended its applications in food processing and as a disinfectant.

<span class="mw-page-title-main">Disinfectant</span> Antimicrobial agent that inactivates or destroys microbes

A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life. Disinfectants are generally distinguished from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides—the latter are intended to destroy all forms of life, not just microorganisms. Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. It is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface.

<span class="mw-page-title-main">Hypochlorous acid</span> Chemical compound

Hypochlorous acid is an acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite, ClO−. HClO and ClO− are oxidizers, and the primary disinfection agents of chlorine solutions. HClO cannot be isolated from these solutions due to rapid equilibration with its precursor, chlorine.

<span class="mw-page-title-main">Hypochlorite</span> Ion

In chemistry, hypochlorite, or chloroxide is an anion with the chemical formula ClO−. It combines with a number of cations to form hypochlorite salts. Common examples include sodium hypochlorite and calcium hypochlorite. The Cl-O distance in ClO− is 1.69 Å.

Shock chlorination is a process used in many swimming pools, water wells, springs, and other water sources to reduce the bacterial and algal residue in the water. Shock chlorination is performed by mixing a large amount of sodium hypochlorite, which can be in the form of a powder or a liquid such as chlorine bleach, into the water. The common advice is that the amount added must raise the level of chlorine to 10X the level of chloramines present in the pool water; this is "shocking". A lesser ratio is termed superchlorinating. Water that is being shock chlorinated should not be swum in or drunk until the sodium hypochlorite count in the water goes down to three ppm or less. Commercial sodium hypochlorite should not be mixed with commercial calcium hypochlorite, as there is a risk of explosion. Although a verb for superchlorination, "shock" is often misunderstood to be a unique type of product.

Calcium hypochlorite is an inorganic compound with formula Ca(ClO)2. It is a white solid, although commercial samples appear yellow. It strongly smells of chlorine, owing to its slow decomposition in moist air. This compound is relatively stable as a solid and solution and has greater available chlorine than sodium hypochlorite. "Pure" samples have 99.2% active chlorine. Given common industrial purity, an active chlorine content of 65-70% is typical. It is the main active ingredient of commercial products called bleaching powder, used for water treatment and as a bleaching agent.

Salt water chlorination is a process that uses dissolved salt for the chlorination of swimming pools and hot tubs. The chlorine generator uses electrolysis in the presence of dissolved salt to produce chlorine gas or its dissolved forms, hypochlorous acid and sodium hypochlorite, which are already commonly used as sanitizing agents in pools. Hydrogen is produced as byproduct too.

Monochloramine, often called chloramine, is the chemical compound with the formula NH2Cl. Together with dichloramine (NHCl2) and nitrogen trichloride (NCl3), it is one of the three chloramines of ammonia. It is a colorless liquid at its melting point of −66 °C (−87 °F), but it is usually handled as a dilute aqueous solution, in which form it is sometimes used as a disinfectant. Chloramine is too unstable to have its boiling point measured.

Chloramines refer to derivatives of ammonia and organic amines wherein one or more N−H bonds have been replaced by N−Cl bonds. Two classes of compounds are considered: inorganic chloramines and organic chloramines. Chloramines are the most widely used members of the halamines.

Dakin's solution is a dilute solution of sodium hypochlorite and other stabilizing ingredients, traditionally used as an antiseptic, e.g. to cleanse wounds in order to prevent infection. The preparation was for a time called also Carrel–Dakin solution or Carrel–Dakin fluid.

<span class="mw-page-title-main">Bleach</span> Chemicals used to whiten or disinfect

Bleach is the generic name for any chemical product that is used industrially or domestically to remove colour (whitening) from fabric or fiber or to disinfect after cleaning. It often refers specifically to a dilute solution of sodium hypochlorite, also called "liquid bleach".

<span class="mw-page-title-main">Halazone</span> Chemical compound

Halazone is a chemical compound whose formula can be written as either C
7H
5Cl
2NO
4S or (HOOC)(C
6H
4)(SO
2)(NCl
2). It has been widely used to disinfect drinking water.

<span class="mw-page-title-main">Antoine Germain Labarraque</span> French chemist and pharmacist

Antoine Germain Labarraque was a French chemist and pharmacist, notable for formulating and finding important uses for "Eau de Labarraque" or "Labarraque's solution", a solution of sodium hypochlorite widely used as a disinfectant and deodoriser.

<span class="mw-page-title-main">Water chlorination</span> Chorination of water

Water chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water. This method is used to kill bacteria, viruses and other microbes in water. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid.

Potassium hypochlorite is the potassium salt of hypochlorous acid. It is used in variable concentrations, often diluted in water solution. It has a light grey color and a strong chlorine smell. It can be used as a disinfectant.

A mixed oxidant solution (MOS) is a type of disinfectant that has many uses including disinfecting, sterilizing, and eliminating pathogenic microorganisms in water. An MOS may have advantages such as a higher disinfecting power, stable residual chlorine in water, elimination of biofilm, and safety. The main components of an MOS are chlorine and its derivatives, which are produced by electrolysis of sodium chloride. It may also contain high amounts of hydroxy radicals, chlorine dioxide, dissolved ozone, hydrogen peroxide and oxygen from which the name "mixed oxidant" is derived.

<span class="mw-page-title-main">Liquid bleach</span>

Liquid bleach, often called just bleach, is a common chemical household product that consists of a dilute solution of sodium hypochlorite and other secondary ingredients. It is a chlorine releasing bleaching agent widely used to whiten clothes and remove stains, as a disinfectant to kill germs, and for several other uses.

References

  1. ↑ Cheesbrough M (2005). District Laboratory Practice in Tropical Countries. Cambridge University Press. p. 68. ISBN   9781139445290.
  2. 1 2 3 4 5 6 7 8 9 10 11 World Health Organization (2009). Stuart MC, Kouimtzi M, Hill SR (eds.). WHO Model Formulary 2008. World Health Organization. pp. 323–324. hdl:10665/44053. ISBN   9789241547659.
  3. 1 2 3 4 5 6 7 Hayes R (2013). Food Microbiology and Hygiene (2nd ed.). Springer Science & Business Media. p. 361. ISBN   9781461535461.
  4. 1 2 3 4 5 Block SS (2001). Disinfection, Sterilization, and Preservation. Lippincott Williams & Wilkins. p. 1082. ISBN   9780683307405.
  5. ↑ Bartels V (2011). Handbook of Medical Textiles. Elsevier. p. 370. ISBN   9780857093691.
  6. 1 2 Sondossi M (2000). "Biocides". In Alexander M, Bloom BR, Hopwood DA, Hull R, Iglewski B, Laskin AI, Oliver SG, Schaechter M, Summers WC (eds.). Encyclopedia of Microbiology, Four-Volume Set (2 ed.). Academic Press. p. 447. ISBN   9780080548487.
  7. ↑ World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl: 10665/325771 . WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  8. ↑ Royal Society for the Prevention of Accidents (2002): 24th Report of the Home and Leisure Accident Surveillance System (HASS)., page 150. Accessed on 2018-06-18.
  9. ↑ OSHA (2018): "Table Z-1". Appendix to Permissible Exposure Limits – Annotated Tables. Published by U. S. Occupational Safety and Health Administration. Accessed on 2018-06-18.
  10. ↑ Sodium Hypochlorite Chemical Production. by Intratec. 2012-09-27. ISBN   978-0615702179.
  11. ↑ Cotton FA, Wilkinson G (1972). Advanced Inorganic Chemistry. John Wiley and Sons Inc. ISBN   0-471-17560-9.
  12. 1 2 Odabasi M (March 2008). "Halogenated volatile organic compounds from the use of chlorine-bleach-containing household products". Environmental Science & Technology. 42 (5): 1445–1451. Bibcode:2008EnST...42.1445O. doi:10.1021/es702355u. PMID   18441786.
  13. ↑ Rizk-Ouaini R, Ferriol M, Gazet J, Saugier-Cohen A, Therese M (1986). "Oxidation reaction of ammonia with sodium hypochlorite. Production and degradation reactions of chloramines". Bulletin de la Société Chimique de France. 4: 512–521.
  14. ↑ Krieger GR, Sullivan Jr JB (2001). Clinical environmental health and toxic exposures (2nd ed.). Philadelphia, PA: Lippincott Williams & Wilkins. p. 968. ISBN   9780683080278.
  15. ↑ Nickmilder M, Carbonnelle S, Bernard A (February 2007). "House cleaning with chlorine bleach and the risks of allergic and respiratory diseases in children". Pediatric Allergy and Immunology. 18 (1): 27–35. doi:10.1111/j.1399-3038.2006.00487.x. PMID   17295796. S2CID   24606118.
  16. ↑ Eaton AD, Greenberg AE, Rice EW, Clesceri LS, Franson MA, eds. (2005). Standard Methods For the Examination of Water and Wastewater (21 ed.). American Public Health Association. ISBN   978-0-87553-047-5. Method 9060a. Also available on CD-ROM and online by subscription.
  17. 1 2 3 Daufresne M (1916). Mode de préparation de l'hypochlorite de soude chirurgical - Differénce entre la soulution de Dakin et celle de Labarraqu. Vol. xxiv. Presse médicale. p. 474.
  18. ↑ >Dakin HD (August 1915). "On the use of certain antiseptic substances in the treatment of infected wounds". British Medical Journal. 2 (2852): 318–20. doi:10.1136/bmj.2.2852.318. PMC   2303023 . PMID   20767784.
  19. 1 2 Dakin HD, Kunham EK (1918). A Handbook of Antiseptics. New York: Macmillan.
  20. ↑ Hugo W (2012). Inhibition and Destruction of the Microbial Cell. Elsevier. p. 383. ISBN   9780323142304.
  21. ↑ Vogt H, Balej J, Bennett JE, Wintzer P, Sheikh SA, Gallone P (2010). "Chlorine Oxides and Chlorine Oxygen Acids". Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. doi:10.1002/14356007.a06_483.pub2. ISBN   9783527303854. S2CID   96905077.
  22. ↑ "Calcium Hypochlorite: Different forms of calcium hypochlorite" (PDF). World Health Organization . Retrieved 27 May 2012.
  23. ↑ Quinn PJ, Markey BK, Leonard FC, Hartigan P, Fanning S, Fitzpatrick ES (2011). Veterinary Microbiology and Microbial Disease. John Wiley & Sons. p. 866. ISBN   9781118251164.
  24. 1 2 3 "OxyChem Sodium Hypochlorite Handbook" (PDF). oxy.com. OxyChem. Archived from the original (PDF) on 2018-04-18. Retrieved 2018-06-13.
  25. ↑ "Pamphlet 96, The Sodium Hypochorite Manual". www.chlorineinstitute.org. The Chlorine Institute.
  26. 1 2 3 Chisholm H, ed. (1911). "Bleaching"  . Encyclopædia Britannica (11th ed.). Cambridge University Press.
  27. ↑ Labarraque AM (1828). On the disinfecting properties of Labarraque's preparations of chlorine. Translated by Scott J. S. Highley.
  28. ↑ "Labarraque AG". Nouvelle Biographie Générale . 28: 323–324. 1859.
  29. ↑ Reece RJ (1907). Report on the Epidemic of Enteric Fever in the City of Lincoln, 1904-5. Thirty-Fifth Annual Report of the Local Government Board, 1905-6: Supplement Containing the Report of the Medical Officer for 1905-6. (Report). London: Local Government Board.
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