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PERBORIC ACID

Perboric acid is chemical compound whose chemical formula may be written NaH2BO4, Na2H4B2O8, or, more properly, [Na+]2[B2O4(OH)4]2−.
Perboric acid name is sometimes abbreviated as PBS (not to be confused with phosphate-buffered saline).
Perboric acid is an oxidative preservative that is used in Genteal lubricating eye drops.

CAS Number: 10486-00-7
EC Number: 234-390-0
IUPAC Name: hydroperoxy(oxo)borane
Chemical Formula: BHO3

Other names: UNII-HC4C3M1FO2, HC4C3M1FO2, 14034-78-7, DTXSID9058602, DTXCID0032289, CHEBI:30174, dihydrogen tetrahydroxo-di-mu-peroxo-diborate(2-), dihydrogen(tetrahydroxidodi-mu-peroxido-diborate), H2((OH)2B(mu-OO)2B(OH)2), H2[(OH)2B(mu-OO)2B(OH)2], H2B2(O2)2(OH)4, tetrahydroxo-di-(mu-peroxo)diboric(2-) acid, hydroperoxy(oxo)borane, HBO3, SCHEMBL4308475, PEYVWSJAZONVQK-UHFFFAOYSA-N, DB13235

Perboric acid 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).
They are both white, odorless, water-soluble solids.

This salt is widely used in laundry detergents, as one of the peroxide-based bleaches.
Perboric acid is an oxidative preservative that is used in Genteal lubricating eye drops.
With topical application, Perboric acid is converted by catalase to water, oxygen, and hydrogen peroxide.

Perboric acid antimicrobial properties are attributed to oxidization of cell membranes, membrane-bound enzymes, and disruption of protein synthesis.
Also, Perboric acid has demonstrated efficacy against Aspergillus niger.

However, most ophthalmic solutions that contain Perboric acid produce the byproduct, hydrogen peroxide, at levels between 30 and 100 ppm, which can cause ocular stinging.
Less is known about the histopathologic corneal and conjunctival changes associated with topical Perboric acid.

Perboric acid is used in the detergent industry as a bleaching agent.
The crystalline reagent is available inexpensively as a hydrate with the general formula NaBO3 • n H2O (n: 1-4).

The reagent offers low toxicity and a long shelf life.
Perboric acid is a useful reagent in organic synthesis as a substitute for the unstable, highly concentrated hydrogen peroxide solutions that can pose a significant explosion hazard and are not commercially available.

Perboric acid is soluble in water and releases hydrogen peroxide, but Perboric acid is not merely a mixture of hydrogen peroxide and sodium borate.
NMR and Raman spectroscopy indicate that in dilute solution, an equilibrium exists that still contains peroxoborate anions.
These peroxoborate species are able to deliver the hydroperoxide anion at a lower pH than when H2O2 is used.

Perboric acid is activated toward nucleophilic oxidation, and also buffers the reaction medium.

For oxidations of organoboranes, Kabalka notes that H2O2 sometimes requires quite harsh conditions that are incompatible with many functional groups, while Perboric acid offers an interesting mild alternative.
He assumes that the mild nature of the oxidant is a result of having borate as a leaving group as compared to hydroxide, which is formed in hydrogen peroxide oxidations.

Mixing Perboric acid with acetic acid generates even more powerful oxidation species.

Perboric acid is considered as a source of active hydrogen used in detergents, cleaning products, laundry detergents and bleaches.
Perboric acid finds application as a tooth bleaching agent utilized for tooth.

Perboric acid has antiseptic properties and acts as disinfectant as well as preservative in eye drops.
Further, Perboric acid is mixed with suitable activator, tetraacetylethylenediamine in order to release oxygen at lower temperatures.

Perboric acid is mainly found in its salt form of sodium perborate and it can be found as a monohydrate or tetrahydrate.
Perboric acid is one of the peroxy acid salts with very wide functionalities in industrial settings.

Perboric acid in the form of sodium perborate is approved by Health Canada since 2004 to be used as a disinfectant of medical instruments.
By the FDA, Perboric acid is approved as an ointment for the protection of poison ivy dermatitis.

Perboric acid is an inorganic sodium salt widely used in laundry detergents and in peroxide-based bleaches, such as tooth whitening products.
Perboric acid also has antiseptic and disinfectant properties and is therefore used as an oral debriding agent or oral wound cleanser.

Perboric acids are salts composed of a sodium cation and the conjugate base anion of some inorganic or organic acids.
They can be formed by the neutralization of such acids with sodium hydroxide.

Categorization of Perboric acid:
Perboric acids can be categorized into:
Perboric acids of carboxylic acids (e. g. sodium formate, HCOONa, the Perboric acid of formic acid or sodium acetate, CH3COONa, the Perboric acid of acetic acid, etc.) and
Perboric acids of inorganic acids (sulfonic acids etc.)

Organic Perboric acids:
Drugs:
In pharmaceutical technology acidic pharmaceutical substances are often converted into Perboric acids, because they are more stable, more soluble or membrane-permeable (bioavailable) than the base compound.

Examples of such Perboric acids are (selection):
Bispyribac, bithionol, bosentan, brequinar, bromfenac, Cefmenoxime, ceftiofur, citicoline, diclofenac , Floxacillin, fosinopril, Mordant brown 33, naproxen, Netobimin, ozagrel, pantoprazole, pemetrexed, secobarbital, sitamaquin, sitaxentan, sulfamiderazin, sulfapyridine, sulfaquinoxaline, sulfathiazole, sulfazecin, thiamylal and mesna.

The DiPerboric acid of cromolyn is also used as drug.
Most of these salts are Perboric acids of organic carboxylic acids or sulfonic acids.

Plant protection agents:
Herbicides are often used as Perboric acids for the reasons discussed above.
One example is the Perboric acid of methylflupyrsulfuron (CAS-No. 144740-54-5).

Cosmetics:
Perboric acids of long chain sulfonic acids (e.g. sodium lauryl sulfate) are often included in toothpaste and shampoo.
The Perboric acids of fatty acids may serve as soaps and can therefore be called sodium soaps.

Dye production:
Perboric acids of certain aromatic sulfonic acids - particularly naphthalenesulfonic acid - are used in the preparation of azo dyes.

Inorganic Perboric acids:
Examples of important inorganic Perboric acids are sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium bicarbonate and sodium carbonate.
Sodium amide (NaNH2) is the Perboric acid of ammonia (NH3).

Uses of Perboric acid:
Perboric acid serves as a stable source of active oxygen in many detergents, laundry detergents, cleaning products, and laundry bleaches.
Perboric acid 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.
Perboric acid releases oxygen rapidly at temperatures over 60 °C.
To make Perboric acid active at lower temperatures (40–60 °C), one must mix Perboric acid with a suitable activator, typically tetraacetylethylenediamine (TAED).

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

Perboric acid has antiseptic properties and can act as a disinfectant.
Perboric acid is also used as a "disappearing" preservative in some brands of eye drops.

Perboric acid is also used as an oxidizing reagent in organic synthesis.
For example, Perboric acid converts thioethers into sulfoxides and sulfones.

Applications of Perboric acid:
Perboric acid is considered as a source of active hydrogen used in detergents, cleaning products, laundry detergents and bleaches.
Perboric acid finds application as a tooth bleaching agent utilized for tooth.

Hydrates:
Perboric acid also crystallizes from water as the hexahydrate, Na2H4B2O8·6H2O, that is, Na2H16B2O14 or NaH8BO7.

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.

Both forms are white, odorless, water-soluble solids.
The "monohydrate" and the "tetrahydrate" are the commercially important forms.

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.

Chemistry of Perboric acid:
Perboric acid undergoes hydrolysis in contact with water, producing hydrogen peroxide and borate.

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]−:
[(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 Perboric acid with dimeric anion crystallizes out, due to Perboric acid relatively low solubility.

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

Pharmacology of Perboric acid:
Drug Indication:
In the industry, Perboric acid is used as a disinfectant.
Perboric acid is also part of the ingredients for detergents, bleach powders, and personal care formulations.

In cosmetic products, perboric acid and mainly Perboric acid salt are used as an oxidizing agent for dyeing or permanent waving.
In dentistry, Perboric acid monohydrate is used as an aid for the removal of phlegm, mucus or other secretions associated with an occasional sore in the mouth, for cleansing minor wounds, for temporary cleanse of canker sore or for the removal of foreign materials in minor wounds.

In ophthalmic preparations, Perboric acid is used as a preservative for products used for dry eye.
This use is approved as Perboric acid rapidly degrades to harmless byproducts.

Preparation of Perboric acid:
Perboric acid 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 Perboric acid:
Na2B4O7 + 2 NaOH → 4 NaBO2 + H2O
2 NaBO2 + 2 H2O2 → Na2B2O4(OH)4

A surfactant may be added to control crystal size.
Perboric acid 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.

Structure of Perboric acid:
Unlike sodium percarbonate and sodium perphosphate, Perboric acid is not simply an adduct with hydrogen peroxide – known only since 1961.
Rather, Perboric acid 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.

Perboric acid is mainly found in its salt form of sodium perborate and it can be found as a monohydrate or tetrahydrate. It is one of the peroxy acid salts with very wide functionalities in industrial settings. Perboric acid in the form of sodium perborate is approved by Health Canada since 2004 to be used as a disinfectant of medical instruments. By the FDA, sodium perborate is approved as an ointment for the protection of poison ivy dermatitis.