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boric acid

 
Dictionary: boric acid

n.
A water-soluble white or colorless crystalline compound, H3BO3, used as an antiseptic and preservative and in fireproofing compounds, cosmetics, cements, and enamels.


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Chemistry Dictionary: boric acid
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Any of a number of acids containing boron and oxygen. Used without qualification the term applies to the compound H3BO3 (which is also called orthoboric acid or, technically, trioxoboric(III) acid). This is a white or colourless solid that is soluble in water and ethanol; triclinic; r.d. 1.435; m.p. 169°C. It occurs naturally in the condensate from volcanic steam vents (suffioni). Commercially, it is made by treating borate minerals (e.g. kernite, Na2B4O7.4H2O) with sulphuric acid followed by recrystallization.

In the solid there is considerable hydrogen bonding between H3BO3 molecules resulting in a layer structure, which accounts for the easy cleavage of the crystals. H3BO3 molecules also exist in dilute solutions but in more concentrated solutions polymeric acids and ions are formed (e.g. H4B2O7; pyroboric acid or tetrahydroxomonoxodiboric(III) acid). The compound is a very weak acid but also acts as a Lewis acid in accepting hydroxide ions:

B(OH)3+H2O⇌B(OH)4 +H+
If solid boric acid is heated it loses water and transforms to another acid at 300°C. This is given the formula HBO2 but is in fact a polymer (HBO2)n. It is called metaboric acid or, technically, polydioxoboric(III) acid.

Boric acid is used in the manufacture of glass (borosilicate glass), glazes and enamels, leather, paper, adhesives, and explosives. It is widely used (particularly in the USA) in detergents, and because of the ability of fused boric acid to dissolve other metal oxides it is used as a flux in brazing and welding. Because of its mild antiseptic properties it is used in the pharmaceutical industry and as a food preservative.



Food and Nutrition: boric acid
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Chemically H3BO4, derived from the element boron, boric acid has been used in the past as a preservative in bacon and margarine, but boron accumulates in the body. Formerly used as an anti-infective agent and eye-wash (boracic acid) but there was a high incidence of toxic reactions.

Drug Info: Boric Acid
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Brand names: Borofax®, Collyrium®



Boric Acid skin ointment

What is Boric Acid skin ointment?

BORIC ACID (Borofax®) skin ointment is used to treat skin irritation including dry skin, minor cuts and burns, sunburn, windburn, and insect bites. It is available without a prescription. Generic boric acid products are available.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
• skin that is damaged such as open sores or severe burns
• an unusual reaction to Boric Acid, medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should this medicine be used?

Boric acid skin ointment is for external use only on the skin; do not take by mouth. Follow directions on the label. Wash your hands before and after use. Apply a thin film to the affected areas and rub in gently. Do not use your medicine more often than directed or for a longer period of time than ordered by your prescriber or health care professional. To do so may increase the chance of side effects.

Do not bandage or wrap the skin being treated unless directed to do so by your prescriber or health care professional. If you are to use a dressing (covering) over this medicine, make sure you know how to apply it.

Do not get boric acid in the eyes, nose, or mouth. If it does get on these areas, rinse off right away.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, use it as soon as you can. If it is almost time for your next dose, use only that dose. Do not use double or extra doses.

What drug(s) may interact with Boric Acid?

Tell your prescriber or health care professional about other skin products you are using. Do not apply boric acid at the same site as other skin preparations without advice.

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking Boric Acid?

Tell your prescriber or health care professional if the area you are treating does not get better within 2—4 weeks.

Do not get boric acid skin products in your eyes. If you do, rinse your eye with plently of cool tap water.

What side effects may I notice from receiving Boric Acid?

Side effects that you should report to your prescriber or health care professional as soon as possible:
• nausea, vomiting, or diarrhea
• stomach pain
• dark red spots on the skin
• weakness
• headache
• restlessness

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• skin irritation

Where can I keep my medicine?

Store in a tightly closed container between 59 and 77 degrees F (15 and 25 degrees C).

Keep out of the reach of children in a container that small children cannot open.

Last updated: 7/1/2002

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

 
Columbia Encyclopedia: boric acid
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boric acid, any one of the three chemical compounds, orthoboric (or boracic) acid, metaboric acid, and tetraboric (or pyroboric) acid; the term often refers simply to orthoboric acid. The acids may be thought of as hydrates of boric oxide, B2O3. Orthoboric acid, H3BO3 or B2O3·3H2O, is colorless, weakly acidic, and forms triclinic crystals. It is fairly soluble in boiling water (about 27% by weight) but less so in cold water (about 6% by weight at room temperature). When orthoboric acid is heated above 170°C it dehydrates, forming metaboric acid, HBO2 or B2O3·H2O. Metaboric acid is a white, cubic crystalline solid and is only slightly soluble in water. It melts at about 236°C, and when heated above about 300°C further dehydrates, forming tetraboric acid, H4B4O7 or B2O3·H2O. Tetraboric acid is either a vitreous solid or a white powder and is water soluble. When tetraboric or metaboric acid is dissolved it reverts largely to orthoboric acid. The major uses of the boric acids are in forming other boron compounds and in borate salts, e.g., borax. A dilute water solution of boric acid is commonly used as a mild antiseptic and eyewash. Boric acid is also used in leather manufacture, electroplating, and cosmetics. Boric acid can be crystallized from an acidified borax solution. It occurs as the mineral sassolite in the Tuscan region of Italy, where it is also recovered from hot springs and vapors. In the United States boric acid is recovered from brines from Searles Lake in California.


Wikipedia: Boric acid
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Boric acid
Boric-acid-2D.png
Boric acid
Boric acid
IUPAC name
Other names Orthoboric acid,
Boracic acid,
Sassolite,
Optibor,
Borofax
Identifiers
CAS number 10043-35-3 Yes check.svgY
PubChem 7628
SMILES
InChI
InChI key KGBXLFKZBHKPEV-UHFFFAOYAI
ChemSpider ID 7346
Properties
Molecular formula H3BO3
Molar mass 61.83 g mol−1
Appearance White crystalline solid
Density 1.435 g/cm3
Melting point

170.9 °C

Boiling point

300 °C

Solubility in water 2.52 g/100 mL (0 °C)
4.72 g/100 mL (20 °C)
5.7 g/100 mL (25°C)
19.10 g/100 mL (80 °C)
27.53 g/100 mL (100 °C)
Solubility soluble in lower alcohols
moderately soluble in pyridine
very slightly soluble in acetone
Acidity (pKa) 9.24 (see text)
Structure
Molecular shape Trigonal planar
Dipole moment Zero
Hazards
MSDS External MSDS
EU classification Toxic (T)
Repr. Cat. 2
R-phrases R60, R61
S-phrases S53, S45
NFPA 704
NFPA 704.svg
0
1
0
 
Flash point Non-flammable.
LD50 2660 mg/kg, oral (rat)
Related compounds
Related compounds Boron trioxide
Borax
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Boric acid, also called boracic acid or orthoboric acid or Acidum Boricum, is a weak acid often used as an antiseptic, insecticide, flame retardant, in nuclear power plants to control the fission rate of uranium, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a white powder and dissolves in water. It has the chemical formula H3BO3, sometimes written B(OH)3. When occurring as a mineral, it is called sassolite.

Contents

Properties

Boric acid was first prepared by Wilhelm Homberg (1652-1715) from borax, by the action of mineral acids, and was given the name sal sedativum Hombergi ("sedative salt of Homberg"). The presence of boric acid or its salts has been noted in seawater. It is also said to exist in plants and especially in almost all fruits.[1] The free acid is found native in certain volcanic districts such as Tuscany, the Lipari Islands and Nevada, issuing mixed with steam from fissures in the ground; it is also found as a constituent of many minerals (borax, boracite, boronatrocaicite and colemanite).

Boric acid is soluble in boiling water. When heated above 170°C it dehydrates, forming metaboric acid HBO2. Metaboric acid is a white, cubic crystalline solid and is only slightly soluble in water. It melts at about 236°C, and when heated above about 300°C further dehydrates, forming tetraboric acid or pyroboric acid, H2B4O7. Boric acid can refer to any of these compounds. Further heating leads to boron trioxide.

Boric acid does not dissociate in aqueous solution, but is acidic due to its interaction with water molecules to form the tetrahydroxyborate ion:

B(OH)3 + H2O is in equilibrium with B(OH)4 + H+ (Ka = 5.8x10−10 mol/l; pKa = 9.24)

Polyborate anions are formed at pH 7–10 if the boron concentration is higher than about 0.025 mol/L. The best known of these is the tetraborate ion, found in the mineral borax:

4 B(OH)4 + 2 H+ ⇌ B4O2−7 + 9 H2O

Boric acid makes an important contribution to the absorption of low frequency sound in seawater.[2]

Crystal structure

Crystalline boric acid consists of layers of B(OH)3 molecules held together by hydrogen bonds. The distance between two adjacent layers is 318 pm.

Boric-acid-unit-cell-3D-balls.png
Boric-acid-layer-3D-balls.png
The unit cell of boric acid
Hydrogen bonding (dashed lines)
allows boric acid molecules to form
parallel layers in the solid state

Toxicology

Based on mammal median lethal dose (LD50) rating of 2,660 mg/kg body mass, boric acid is poisonous if taken internally or inhaled. However, it is generally considered to be not much more toxic than table salt.[3] The Thirteenth Edition of the Merck Index indicates that the LD50 of boric acid is 5.14 g/kg for oral dosages given to rats, and that 5 to 20 g/kg has produced death in adult humans. The LD50 of sodium chloride is reported to be 3.75 g/kg in rats according to the Merck Index.

Long term exposure to boric acid may be of more concern, causing kidney damage and eventually kidney failure (see links below). Although it does not appear to be carcinogenic, studies in dogs have attributed testicular atrophy after exposure to 32 mg/kg bw/day for 90 days. This level is far lower than the LD50.[4]

According to boric acid IUCLID Dataset published by the European Commission, boric acid in high doses shows significant developmental toxicity and teratogenicity in rabbit, rat, and mouse fetus such as cardiovascular defects, skeletal variations, mild kidney lesions.[5] As a consequence, in August 2008, in the 30th ATP to EU directive 67/548/EEC, the EC decided to amend its classification as reprotoxic cat. 2 and R60 (may impair fertility) R61 (may cause harm to the unborn child).[6][7][8][9][10]

Uses

Medicinal

Boric acid can be used as an antiseptic for minor burns or cuts and is sometimes used in dressings or salves or is applied in a very dilute solution as an eye wash in a 1.5% solution or 1 tbsp (15 ml) per quart (very close to a liter) of sterilised water. As an anti-bacterial compound, boric acid can also be used as an acne treatment. Boric acid can be used to treat yeast and fungal infections such as candidiasis (vaginal yeast infections) by inserting a vaginal suppository containing 600 mg of boric acid daily for 14 days (PMID 10865926) or for yeast infection of the male pubic region (jock-itch or strong genital odor) by applying the powder to the skin all over the pubic region for several days to a week. It is also used as prevention of athlete's foot, by inserting powder in the socks or stockings, and in solution can be used to treat some kinds of otitis externa (ear infection) in both humans and animals. The preservative in urine sample bottles (red cap) in the UK is boric acid.

Insecticidal

Boric acid was first registered in the US as an insecticide in 1948 for control of cockroaches, termites, fire ants, fleas, silverfish, and many other insects.[11] It acts as a stomach poison affecting the insects' metabolism, and the dry powder is abrasive to the insects' exoskeleton.

Boric acid is generally considered to be safe to use in household kitchens to control cockroaches and ants. Homemade ant bait can be made by dissolving 1 teaspoon powdered boric acid and 10 teaspoons sugar into 2 cups (500 mL) of water; this mixture can then be absorbed into cotton balls which are left near ant trails. This reportedly will be carried back into the ants' nest, killing any ants that eat it, potentially destroying the entire colony.

Boric acid is also made into a paste or gel form as a powerful and effective insecticide much safer to humans than many other insecticides. The paste or gel has attractants in it to attract insects, especially cockroaches, that take the bait back to the nest. Little is necessary for killing insects for up to a year; a small dab under sinks, counters, refrigerators, and stoves is wholly adequate. The boric acid slowly and imperceptibly causes dehydration for which insects can never develop immunity.

Preservation

In combination with its use as an insecticide it also prevents and destroys existing wet and dry rot in timbers. It can be used in combination with an ethylene glycol carrier to treat external wood against fungal and insect attack. It is possible to buy Borate impregnated rods for insertion into wood via drill holes where dampness and moisture is known to collect and sit. It is available in a gel form and injectable paste form for treating rot affected wood without the need to replace the timber. You can buy concentrates of Borate based timber treatments which can be sprayed or dipped. Surface treatments prevent slime, mycelium and algae growth even in marine environments. There is a wide range of manufacturers of wood preservers based on boric acid/ borate mineral salts.

Lubrication

Colloidal suspensions of nano-particles of boric acid dissolved in petroleum or vegetable oil can form a remarkable lubricant on ceramic or metal surfaces with a coefficient of sliding friction that decreases with increasing pressure to a value ranging from 0.1 to 0.02.

Self-lubricating H3BO3 films result from a spontaneous chemical reaction between water molecules and B2O3 coatings in humid environment. In bulk-scale, an inverse relationship exists between friction coefficient and Hertzian contact pressure induced by applied load.

Industrial

The primary industrial use of boric acid is in the manufacture of monofilament fiberglass usually referred to as textile fiberglass. Textile fiberglass is used to reinforce plastics in applications that range from boats, to industrial piping to computer circuit boards.[12]

Boric acid is used in nuclear power plants to slow down the rate at which fission is occurring. Fission chain reactions are generally driven by the amount of neutrons present (as products from previous fissions). Natural boron is 20% boron-10 and about 80% boron-11. Boron-10 has a high cross-section for absorption of low energy (thermal) neutrons. By adding more boric acid to the reactor coolant which circulates through the reactor, the probability that a neutron can survive to cause fission is reduced. Therefore, boric acid concentration changes effectively regulate the rate of fissions taking place in the reactor. This is only done in pressurized water reactors (PWR's). Boron is also dissolved into the spent fuel pools containing used uranium rods. The concentration is high enough to keep neutron multiplication at a minimum.

In the jewelry industry, boric acid is often used in combination with denatured alcohol to reduce surface oxidation and firescale from forming on metals during annealing and soldering operations.

Boric acid is used in producing the glasses of LCD flat panel displays.

In electroplating, boric acid is used as part of some proprietary formulas. One such known formula calls for about a 1 to 10 ratio of H3BO3 to NiSO4, a very small portion of sodium lauryl sulfate and a small portion of H2SO4.

It is also used in the manufacturing of remming mass, a fine silica-containing powder used for producing induction furnace linings and ceramics.

Miscellaneous

Borates including boric acid have been used since the time of the Greeks for cleaning, preserving food, and other activities.[citation needed]

Silly Putty was originally made by adding boric acid to silicone oil.

TBE buffer is widely used for the electrophoresis of nucleic acids and has a higher buffer capacity than a TAE buffer. It can be used for DNA and RNA polyacrylamide and agarose gel electrophoresis.

It is used in pyrotechnics to prevent the amide-forming reaction between aluminium and nitrates. A small amount of boric acid is added to the composition to neutralize alkaline amides that can react with the aluminium.

Boric acid dissolved in methanol is popularly used among fire jugglers and fire spinners to create a deep green flame.

The white powder is also used in India and across the world to dust down Carrom boards to decrease friction and increase speed of play.[13]

Boric acid is added to salt in the curing of cattle hides, calfskins and sheepskins. Used in that way it helps to control bacteria development and also aids in the control of insects.

References

  1. ^ A. H. Allen (1904). "The determination of boric acid in cider, fruits, etc". Analyst 29: 301. doi:10.1039/an9042900301. 
  2. ^ "Underlying physics and mechanisms for the absorption of sound in seawater". National Physical Laboratory. http://resource.npl.co.uk/acoustics/techguides/seaabsorption/physics.html. Retrieved 2008-04-21. 
  3. ^ F. Jay Murray (2004). "Don’t Lose Sleep Over Borates and Mattresses". Murray and Associates. http://web.archive.org/web/20070819100438/http://www.natbat.com/docs/boron.htm. Retrieved 2008-04-21. 
  4. ^ Office of Prevention, Pesticides and Toxic Substances (2006) (.PDF). Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Eligibility Decision (TRED) for Boric Acid/Sodium Borate Salts. United States Environmental Protection Agency. http://www.epa.gov/oppsrrd1/REDs/boric_acid_tred.pdf. Retrieved 2008-04-21. 
  5. ^ European Chemical Bureau - ECB (.PDF). Boric Acid IUCLID Dataset. European Commission. http://ecb.jrc.ec.europa.eu/IUCLID-DataSheets/10043353.pdf. 
  6. ^ "Boric acid, ACC# 03260". MSDS. 2008-02-11. http://lifesciences.byu.edu/safety/LabSafety/BoricAcid.pdf. Retrieved 2009-09-24. 
  7. ^ Ishii Y; Fujizuka N; Takahashi T; Shimizu K; Tuchida A; Yano S; Naruse T; Chishiro T. (1993). "A fatal case of acute boric acid poisoning". J Toxicol Clin Toxicol (Nagano, Japan) 31 (2): 345-352. PMID 8492348. http://www.ncbi.nlm.nih.gov/pubmed/8492348. 
  8. ^ Restuccio, A.; Mortensen, M. E.; Kelley, M. T. (November 1992). "Fatal ingestion of boric acid in an adult". Am J Emerg Med 10 (6): 545-547. PMID 1388380. http://www.find-health-articles.com/rec_pub_1388380-fatal-ingestion-boric-acid-adult.htm. 
  9. ^ John E. Duldner (2009-01-30). "Boric acid poisoning". A.D.A.M. Medical Encyclopedia. MedLine Plus. http://www.nlm.nih.gov/medlineplus/ency/article/002485.htm. Retrieved 2009-09-24. 
  10. ^ NSW Food Authority. "Borax and boric acid". Australia: New South Wales Government. http://www.foodauthority.nsw.gov.au/consumers/other-food-topics/borax-and-boric-acid/. Retrieved 2009-09-24. 
  11. ^ Office of Prevention, Pesticides and Toxic Substances (1993) (.PDF). R.E.D. Facts: Boric Acid. United States Environmental Protection Agency. http://www.epa.gov/oppsrrd1/REDs/factsheets/0024fact.pdf. Retrieved 2008-04-21. 
  12. ^ R. B. Kistler; C. Helvaci (1983), Industrial Minerals and Rocks, Science Information Publishing Centre, Government of india's department for Scientific & Industrial Research 
  13. ^ Harpreet Singh. "Standard equipments". Punjab State Carrom Association. http://pscamohali.googlepages.com/standardequipments. Retrieved 2009-09-24. 

Further reading

  • Jolly, W. L. (1991). Modern Inorganic Chemistry (2nd Edn.). New York: McGraw-Hill. ISBN 0-07-112651-1. 
  • Louis Goodman, Alfred Gilman, Laurence Brunton, John Lazo and Keith Parker (2006). Goodman & Gilman's The Pharmacological Basis of Therapeutics. New York: McGraw Hill. 

External links


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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
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Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.  Read more
Drug Info. Gold Standard. Copyright © 2008 by Gold Standard. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/ Read more
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