Chemistry:Sodium perborate

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Sodium perborate
Perborate unit in the "monohydrate"
Names
Other names
Sodium peroxoborate,[1] PBS-1 ("monohydrate"), PBS-4 ("tetrahydrate")
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
EC Number
  • 231-556-4
RTECS number
  • SC7350000
UNII
UN number 1479
Properties
NaBO
3 · nH
2O
Molar mass 99.815 g/mol ("monohydrate");
153.86 g/mol ("tetrahydrate")
Appearance White powder
Odor Odorless
Melting point 63 °C (145 °F; 336 K) ("tetrahydrate")
Boiling point 130 to 150 °C (266 to 302 °F; 403 to 423 K) ("tetrahydrate", decomposes)
2.15 g/(100 mL) ("tetrahydrate", 18 °C)
Pharmacology
1=ATC code }} A01AB19 (WHO)
Hazards
Safety data sheet ICSC 1046
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
1
1
0
Flash point Non-flammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☑Y verify (what is ☑Y☒N ?)
Infobox references
Tracking categories (test):
In the following text, hydration states in quotation marks indicate incorrect common names.

Sodium perborate is chemical compound whose chemical formula may be written NaH
2BO
4, Na
2H
4B
2O
8, or, more properly, [Na+
]
2[B
2O
4(OH)
4]2−. Its name is sometimes abbreviated as PBS (not to be confused with phosphate-buffered saline).

The compound is commonly encountered in anhydrous form or as a hexahydrate (commonly called "monohydrate" or PBS-1 and "tetrahydrate" or PBS-4, after the early assumption that NaBO
3 would be the anhydrous form).[2] They are both white, odorless, water-soluble solids.[3]

This salt is widely used in laundry detergents, as one of the peroxide-based bleaches.

Structure

Unlike sodium percarbonate and sodium perphosphate, the compound is not simply an adduct with hydrogen peroxide – known only since 1961.[4][1] Rather, it contains a perborate anion [(B(OH)
2OO)
2]2− consisting of a cyclic –B–O–O–B–O–O– core with two hydroxy groups attached to each boron atom. The ring adopts a chair conformation.[5]

Hydrates

The compound also crystallizes from water as the hexahydrate, Na
2H
4B
2O
8 · 6H2O, that is, Na
2H
16B
2O
14 or NaH
8BO
7.[citation needed]

The anhydrous compound is commonly but incorrectly called a "monohydrate" after the historical formulation NaBO
3 · H2O instead of the correct Na
2H
4B
2O
8. Likewise, the hexahydrate is usually called "tetrahydrate" and formulated as NaBO
3 · 4H2O.[2] Both forms are white, odorless, water-soluble solids.[3] The "monohydrate" and the "tetrahydrate" are the commercially important forms.[3]

There does exist a true tetrahydrate Na
2H
4B
2O
8 · 4H2O, traditionally known as the "trihydrate", with no industrial significance. There is a CAS number for each of the three traditional "hydrates", the three "peroxyborate" versions of each (interpreted as a hydrogen peroxide adduct) and the poorly-defined "anhydrate" NaBO
3, totalling seven.[1]

Chemistry

Sodium perborate undergoes hydrolysis in contact with water, producing hydrogen peroxide and borate.[3]

More precisely, in solution the cyclic anion hydrolizes into two anions [B(OH)
3(OOH)]−
, which then enter in equilibrium with boric acid B(OH)
3, hydrogen peroxide H
2O
2, the hydroperoxyl anion −
OOH, and the tetrahydroxyborate anion [B(OH)
4]−
:[2]

[(B(OH)
2OO)
2]2− + 2 H
2O ⇌ 2 [B(OH)
3(OOH)]−
[B(OH)
3(OOH)]−
 ⇌ B(OH)
3 + −
OOH
B(OH)
3 + −
OOH + H
2O ⇌ [B(OH)
4]−
 + H
2O
2

As the concentration of the solution increases, other peroxoborate species become significant. With excess H
2O
2, the anions [B(OH)
2(OOH)
2]−
, [B(OH)(OOH)
3]−
, and eventually [B(OOH)
4]−
 appear. At high borate concentrations, the sodium perborate with dimeric anion crystallizes out, due to its relatively low solubility.[2]

The "monohydrate" form dissolves faster than the "tetrahydrate" and has higher heat stability; it is prepared by heating the "tetrahydrate".[1] The commercial "anhydrate", or Oxoborate, is prepared by further heating of "monohydrate" and actually consists of sodium borate and boron–oxygen radical.[1]

Preparation

Sodium perborate is manufactured by reaction of borax Na
2B
4O
7 and sodium hydroxide NaOH to give sodium metaborate NaBO
2, which is then reacted with hydrogen peroxide to give hydrated sodium perborate:[3][6]

Na
2B
4O
7 + 2 NaOH → 4 NaBO
2 + H
2O
2 NaBO
2 + 2 H
2O
2 → Na
2B
2O
4(OH)
4

A surfactant may be added to control crystal size.[7][8]

It may also be produced in the electrolysis of an aqueous solution of a solution containing borax, sodium carbonate and sodium bicarbonate (potassium dichromate is added to improve yield along with sodium silicate). A copper pipe is used as a cathode and platinum for the anode, the current being 6 amperes at 7 to 8 volts, and the temperature 10 °C.[9]

Uses

Sodium perborate serves as a stable source of active oxygen in many detergents, laundry detergents, cleaning products, and laundry bleaches.[3] It is a less aggressive bleach than sodium hypochlorite and other chlorine-based bleaches, causing less degradation to dyes and textiles. Borates also have some non-oxidative bleaching properties.[citation needed] Sodium perborate releases oxygen rapidly at temperatures over 60 °C. To make it active at lower temperatures (40–60 °C), one must mix it with a suitable activator, typically tetraacetylethylenediamine (TAED).

The compound has antiseptic properties and can act as a disinfectant. It is also used as a "disappearing" preservative in some brands of eye drops.[citation needed]

Sodium perborate is also used as an oxidizing reagent in organic synthesis. For example, it converts thioethers into sulfoxides and sulfones.[10]

Dental use

Sodium perborate monohydrate is quickly hydrolyzed into hydrogen peroxide and borate on contact with water.[3] A 1979 double-blind crossover study[11] suggests that hydrogen peroxide, which is released during the use of this product, may prevent or retard colonization and multiplication of anaerobic bacteria, such as those that inhabit oral wounds.

Sodium perborate is also present in some tooth bleaching formulas for non vital root treated teeth. The compound is inserted in the root canal and left in place for an extended period of time to allow it to diffuse into the tooth and bleach stains from the inside out. However, this use has been banned in the European Union.[12]

Safety

In the European Union, sodium perborate, like most borates, was classified as "carcinogenic, mutagenic, or toxic for reproduction" (CMR), category 1B of Regulation (EC) 790/2009, as a result of being included in Part 3 of Annex VI of the regulation 1272/2008 on Classification, Labelling and Packaging (CLP) of substances and mixtures. As a result, their use has been automatically banned in cosmetic products in the EU, in any concentration, starting 1 December 2010. That extends to the use of perborates for tooth whitening.[12]

Brands

Bocasan

Bocasan was an oral wound cleanser manufactured in the United Kingdom by Knox Laboratories Ltd of London from 1960–1975,[13] before being rebranded as an Oral-B product [14]

Bocasan dental rinse front
Bocasan dental rinse back

Production of Bocasan appears to have ceased by 2003. A similar product, Amosan was available for a period before also ceasing production in 2010. As of 2013, a Dutch pharmacy offers the same formulation under the name Bikosan[15]

It was used to aid treatment, in adults or children over 5 years old, of periodontal conditions such as canker sores, denture irritation, orthodontic irritation, or after dental procedures.

Bocasan was packaged in a 1.7 gram envelope, and contained 69.72% sodium perborate monohydrate and 29.68% sodium hydrogen tartrate anhydrous. To use, the contents were dissolved in 30 cubic centimetres of warm water. Half the amount was swilled around the mouth for two minutes and discarded, and the procedure repeated with the remainder. Treatment was recommended three times a day after meals.

A 1979 double-blind crossover study[16] suggests that hydrogen peroxide, which is released during the use of this product, may prevent or retard colonization and multiplication of anaerobic bacteria, such as those that inhabit oral wounds. A small (n=12) 1998 RCT shows that Bocasan combined with chlorhexidine mouthwash is better than chlorhexidine alone in preventing plaque.[17] A further study (n=28) shows that Bocasan reduces the staining associated with chlorhexidine.[18]

Drug facts

  • Active ingredient: Sodium perborate monohydrate
  • Inactive ingredients: Sodium hydrogen tartrate
  • Purpose: Oral cleanser
  • Normal use: Use up to three times daily, after meals or as directed by a dentist

Amosan

Amosan Oral Antiseptic Rinse, 2014

Amosan[19] is an oral antiseptic rinse. It contains 68.635% sodium perborate monohydrate by weight. Sold as a powder customarily packaged in 1.7g envelopes, it reconstitution with warm water, after which it is used as a mouth rinse. It is used to aid in the prevention of, as well as speed the recovery from canker sores, denture irritation, orthodontic irritation, and oral injuries or after dental procedures.

History

Amosan was originally made by Oral-B; a mention of the powder appeared in the February 6, 1970 Federal Register.[20] Between 2005 and 2010, Amosan was manufactured in Belgium and sold under the Oral-B brand, belonging to Procter & Gamble after its 2005 acquisition of Gillette. In December 2010, its use was banned in the EU, as the product is based on borate, which the union considers "carcinogenic, mutagenic, or toxic for reproduction".[12]

Vintage Brands Limited began manufacturing and selling Amosan Oral Antiseptic Rinse in 2014 because many consumers were disappointed that it was no longer available.[21] Product review pages on Amazon[22] and public comment forums elsewhere[23] indicate a high level of frustration with the discontinuation by users who could find no effective alternative treatment.

In April 2012, it was reported that Shoppers Drug Mart in Canada had produced a comparable product under their house brand: 'Life Brand Oral Wound Cleanser'.[24] Also, Jean Coutu and Rexall has their own house brand versions.

Drug facts

  • Active ingredient: Sodium perborate monohydrate 1.2 g
  • Inactive ingredients: L-Tartaric acid, sodium saccharin, flavors
  • Purpose: Oral wound cleanser
  • Normal use: Use up to 4 times daily, after meals and before bedtime or as directed by a dentist or physician

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Harald Jakob. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. 
  2. ↑ 2.0 2.1 2.2 2.3 Alexander McKillop and William R Sanderson (1995): "Sodium perborate and sodium percarbonate: Cheap, safe and versatile oxidising agents for organic synthesis". Tetrahedron, volume 51, issue 22, pages 6145-6166. doi:10.1016/0040-4020(95)00304-Q
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 B.J. Brotherton "Boron: Inorganic Chemistry" in Encyclopedia of Inorganic Chemistry (1994) Ed. R. Bruce King, John Wiley & Sons ISBN:0-471-93620-0
  4. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. 
  5. ↑ Carrondo, M. A. A. F. de C. T.; Skapski, A. C. (1978). "Refinement of the X-ray crystal structure of the industrial bleaching agent disodium tetrahydroxo-di-μ-peroxo-diborate hexahydrate, Na2[B2(O2)2(OH)4]·6H2O". Acta Crystallogr B 34: 3551. doi:10.1107/S0567740878011565. 
  6. ↑ "Sodium Perborate REACH Consortium". http://www.perborates.eu/docs/PBS_SIP1010.pdf. Retrieved 2012-06-07. 
  7. ↑ J. Dugua and B.Simon (1978): "Crystallization of sodium perborate from aqueous solutions: I. Nucleation rates in pure solution and in presence of a surfactant". Journal of Crystal Growth, volume 44, issue 3, pages 265-279.doi:10.1016/0022-0248(78)90025-8
  8. ↑ J. Dugua and B.Simon (1978): "Crystallization of sodium perborate from aqueous solutions: II. Growth kinetics of different faces in pure solution and in the presence of a surfactant". Journal of Crystal Growth, volume 44, issue 3, pages 280-286.doi:10.1016/0022-0248(78)90026-X
  9. ↑ Paul, Mollard (12 June 1962). "US3038842A Process of making sodium perborate by electrolysis". https://patents.google.com/patent/US3038842A/en. 
  10. ↑ McKillop, Alexander; Kabalka, George W.; Reddy, Marepally Srinivasa (2008-09-15), John Wiley & Sons, Ltd, ed. (in en), Sodium Perborate, Chichester, UK: John Wiley & Sons, Ltd, pp. rs094.pub2, doi:10.1002/047084289x.rs094.pub2, ISBN 978-0-471-93623-7, http://doi.wiley.com/10.1002/047084289X.rs094.pub2, retrieved 2021-01-18 
  11. ↑ Wennstrom, Jan; Lindhe, Jan (Apr 1979). "Effect of hydrogen peroxide on developing plaque and gingivitis in man.". J Clin Periodontol 6 (2): 115–30. doi:10.1111/j.1600-051x.1979.tb02190.x. PMID 379049. 
  12. ↑ 12.0 12.1 12.2 Nature Inc. (2015): "Chemical used in beauty salon teeth whitening banned by EU". BDJ Team, volume 2, article 15075, 26 June 2015. doi:10.1038/bdjteam.2015.75
  13. ↑ "Two sachets of Bocasan mouthwash powder, supplied by Knox la < CultureGrid". http://www.culturegrid.org.uk/static/showResource/3051671. 
  14. ↑ Medicines: The Comprehensive Guide edited by Dr. Ian Morton, Judith M. Hall. Royal Society of Medicine. Bloomsbury Publishing, London, 2002. Pg 118
  15. ↑ "Home ⋆ Bik & Bik Online Pharmacy". https://www.bik-bik.com/info/14/bikosan-replaces-bocasan. 
  16. ↑ Wennstrom, Jan; Lindhe, Jan (April 1979). "Effect of hydrogen peroxide on developing plaque and gingivitis in man". Journal of Clinical Periodontology 6 (2): 115–30. doi:10.1111/j.1600-051x.1979.tb02190.x. PMID 379049. 
  17. ↑ Dona, BL; Gründemann, LJ; Steinfort, J; Timmerman, MF; van der Weijden, GA (November 1998). "The inhibitory effect of combining chlorhexidine and hydrogen peroxide on 3-day plaque accumulation.". Journal of Clinical Periodontology 25 (11 Pt 1): 879–83. doi:10.1111/j.1600-051x.1998.tb02385.x. PMID 9846796. 
  18. ↑ Gründemann, LJ; Timmerman, MF; Ijzerman, Y; van der Weijden, GA; van der Weijden, GA (January 2000). "Stain, plaque and gingivitis reduction by combining chlorhexidine and peroxyborate.". Journal of Clinical Periodontology 27 (1): 9–15. doi:10.1034/j.1600-051x.2000.027001009.x. PMID 10674956. 
  19. ↑ "Home". http://www.amosan.ca/. 
  20. ↑ Federal register
  21. ↑ Amosan Oral Products Facebook [user-generated source]
  22. ↑ "Amosan Oral Wound Cleanser Powder". Amazon. https://www.amazon.com/Amosan-Oral-Wound-Cleanser-Powder/dp/B000GGHT52. 
  23. ↑ "Bocasan/Amosan". Mouthulcers.org. http://www.mouthulcers.org/messages.php?thread=1463. 
  24. ↑ "Life Brand Oral Wound Cleanser Mouthwash 1.7g x 20 Sachets SKU 057800802228". Shopper Drug Mart / Pharmaprix. http://www1.shoppersdrugmart.ca/en/health-and-pharmacy/personal-care/oral-lip-care/details/057800802228. 

External links



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