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Sodium perborate

Sodium perborate is chemical compound whose chemical formula may be written NaH2BO4, Na2H4B2O8, or, more properly, [Na ]2[B2O4(OH)4]2−. Its name is sometimes abbreviated as PBS (not to be confused with phosphate-buffered saline).

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
ECHA InfoCard 100.035.597 Edit this at Wikidata
EC Number
  • 231-556-4
RTECS number
  • SC7350000
UNII
UN number 1479
  • InChI=1S/B2H4O8.2Na/c3-1(4)7-9-2(5,6)10-8-1;;/h3-6H;;/q-2;2* 1 checkY
    Key: JBUKJLNBQDQXLI-UHFFFAOYSA-N checkY
  • InChI=1/B2H4O8.2Na/c3-1(4)7-9-2(5,6)10-8-1;;/h3-6H;;/q-2;2* 1
    Key: JBUKJLNBQDQXLI-UHFFFAOYAG
  • [Na ].[Na ].O[B-]1(OO[B-](O)(O)OO1)O
Properties
NaBO3·nH2O
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
A01AB19 (WHO)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point Non-flammable
Safety data sheet (SDS) ICSC 1046
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
In the following text, hydration states in quotation marks indicate incorrect common names.

The compound is commonly encountered in anhydrous form or as a hexahydrate (commonly called, respectively, "monohydrate" or PBS-1 and "tetrahydrate" or PBS-4, after the historic assumption that NaBO3 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.

Sodium perborate was first obtained in 1898, independently, by Sebastian Tanatar and by P. Melikoff and L. Pissadewsky; the researchers prepared sodium perborate by treating sodium borate with a solution of hydrogen peroxide and sodium hydroxide, but Tanatar also obtained sodium perborate by electrolysis of a solution of sodium borate.[4][5][6]

Structure

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Unlike sodium percarbonate and sodium perphosphate, the compound is not simply an adduct with hydrogen peroxide – known only since 1961.[7][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.[8]

Hydrates

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The compound also crystallizes from water as the hexahydrate, Na2H4B2O8·6H2O, that is, Na2H16B2O14 or NaH8BO7.[citation needed]

The anhydrous compound is commonly but incorrectly called a "monohydrate" after the historical formulation NaBO3·H2O instead of the correct Na2H4B2O8. Likewise, the hexahydrate is usually called "tetrahydrate" and formulated as NaBO3·4H2O.[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 Na2H4B2O8·4H2O, 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" NaBO3, totalling seven.[1]

Chemistry

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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 H2O2, the hydroperoxyl anion −OOH, and the tetrahydroxyborate anion [B(OH)4]−:[2]

[(B(OH)2OO)2]2− 2 H2O ⇌ 2 [B(OH)3(OOH)]−
[B(OH)3(OOH)]− ⇌ B(OH)3 −OOH
B(OH)3 −OOH H2O ⇌ [B(OH)4]− H2O2

As the concentration of the solution increases, other peroxoborate species become significant. With excess H2O2, 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

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Sodium perborate is manufactured by reaction of borax Na2B4O7 and sodium hydroxide NaOH to give sodium metaborate NaBO2, which is then reacted with hydrogen peroxide to give hydrated sodium perborate:[3][9]

Na2B4O7 2 NaOH → 4 NaBO2 H2O
2 NaBO2 2 H2O2 → Na2B2O4(OH)4

A surfactant may be added to control crystal size.[10][11]

It may also be produced in the electrolysis of an aqueous 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.[12]

Uses

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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.[13] Another use of sodium perborate in organic synthesis is as a convenient alternative to H2O2, for example in the 2 step conversion of an aryl halide to a phenol (the first step is a Miyaura borylation).[14]

 
Oxidation of Boronate with sodium perborate

Dental use

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Sodium perborate monohydrate is quickly hydrolyzed into hydrogen peroxide and borate on contact with water.[3] A 1979 double-blind crossover study[15] 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.[16]

Safety

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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.[16]

Brands

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Bocasan

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Bocasan was an oral wound cleanser manufactured in the United Kingdom by Knox Laboratories Ltd of London from 1960–1975,[17] before being rebranded as an Oral-B product [18]

 
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[19]

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[20] 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.[21] A further study (n=28) shows that Bocasan reduces the staining associated with chlorhexidine.[22]

Drug facts

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Amosan

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Amosan Oral Antiseptic Rinse, 2014

Amosan[23] 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

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Amosan was originally made by Oral-B; a mention of the powder appeared in the February 6, 1970 Federal Register.[24] 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".[16]

Vintage Brands Limited began manufacturing and selling Amosan Oral Antiseptic Rinse in 2014 because many consumers were disappointed that it was no longer available.[25] Product review pages on Amazon[26] and public comment forums elsewhere[27] 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'.[28] Also, Jean Coutu and Rexall has their own house brand versions.

Drug facts

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See also

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References

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  1. ^ a b c d e Harald Jakob; et al. "Peroxy Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN 978-3527306732.
  2. ^ a b c d 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. ^ a b c d e f g 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. ^ Tanatar, S. (1898). "Perborate und ihre Konstitution" [Perborates and their composition]. Zeitschrift für physikalische Chemie (Journal for Physical Chemistry) (in German). 26: 132–134.
    • Tanatar, S. (1898). "Notiz über Perborate" [Notice about perborates]. Zeitschrift für physikalische Chemie (in German). 29: 162–166.
    • Tanatar, S. (1901). "Über Perborate" [About perborates]. Zeitschrift für anorganische und allgemeine Chemie (Journal for Inorganic and General Chemistry) (in German). 26: 345–347.
  5. ^ Melikoff, P.; Pissadewsky, L. (1898). "Hypertitanate und Hyperborate". Berichte der Deutschen Chemischen Gesellschaft (in German). 31: 678–680.
  6. ^ Jakob, Harold; Leininger, Stefan; Lehmann, Thomas; Jacobi, Sylvia; Gutewort, Sven (2007). "Ch. 26: Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Vol. A19. Hoboken, New Jersey, USA: Wiley‐VCH Verlag GmbH & Co. pp. 293–324. doi:10.1002/14356007.a19_177.pub2. See p. 299.
  7. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  8. ^ 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.
  9. ^ "Sodium Perborate REACH Consortium" (PDF). Archived from the original (PDF) on 2014-04-26. Retrieved 2012-06-07.
  10. ^ 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
  11. ^ 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
  12. ^ Paul, Mollard (12 June 1962). "US3038842A Process of making sodium perborate by electrolysis". Google Patents.
  13. ^ McKillop, Alexander; Kabalka, George W.; Reddy, Marepally Srinivasa (2008-09-15), "Sodium Perborate", in John Wiley & Sons, Ltd (ed.), Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, pp. rs094.pub2, doi:10.1002/047084289x.rs094.pub2, ISBN 978-0-471-93623-7, retrieved 2021-01-18
  14. ^ Spirocycloheptanes as inhibitors of rock
  15. ^ 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.
  16. ^ a b c 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
  17. ^ "Two sachets of Bocasan mouthwash powder, supplied by Knox la < CultureGrid".
  18. ^ Medicines: The Comprehensive Guide edited by Dr. Ian Morton, Judith M. Hall. Royal Society of Medicine. Bloomsbury Publishing, London, 2002. Pg 118
  19. ^ "Home ⋆ Bik & Bik Online Pharmacy".
  20. ^ 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.
  21. ^ 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.
  22. ^ 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.
  23. ^ "Home". amosan.ca.
  24. ^ Federal register
  25. ^ Amosan Oral Products Facebook [user-generated source]
  26. ^ "Amosan Oral Wound Cleanser Powder". Amazon.com. Amazon.
  27. ^ "Bocasan/Amosan". Mouthulcers.org.
  28. ^ "Life Brand Oral Wound Cleanser Mouthwash 1.7g x 20 Sachets SKU 057800802228". Shopper Drug Mart / Pharmaprix. Archived from the original on 2016-03-04. Retrieved 2014-09-25.
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