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
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 ?)

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).

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 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.

Structure

Unlike

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, 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

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

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][6]

Na2B4O7 + 2 NaOH → 4 NaBO2 + H2O
2 NaBO2 + 2 H2O2 → Na2B2O4(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

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

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

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

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-
    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

External links