Boric acid, also called
boracic acid or
orthoboric acid or
Acidum Boricum, is a weak
acidAn acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion activity greater than in pure water, i.e. a pH less than 7.0...
often used as an
antisepticAntiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
,
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
,
flame retardantFlame retardants are materials that inhibit or resist the spread of fire. These can be separated into several categories:*Minerals such as asbestos, compounds such as aluminium hydroxide, magnesium hydroxide, hydromagnesite, antimony trioxide, various hydrates, red phosphorus, and boron compounds,...
, in nuclear power plants to control the fission rate of
uraniumUranium is a silvery-white metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. Besides its 92 protons, a uranium nucleus can have between 141 and 146 neutrons. The most common uranium isotopes are U-238 and U-235 . A uranium atom has...
, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a white powder and dissolves in
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
. It has the
chemical formulaA chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
HHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
3BBoron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a trivalent metalloid element which occurs abundantly in the evaporite ores borax and ulexite....
OOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
3, sometimes written B(OH)
3. When occurring as a
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
, it is called
sassoliteSassolite is a borate mineral, and is the mineral form of boric acid. It occurs in volcanic fumaroles and hot springs, as well as in bedded sedimentary borate deposits. Its mineral form was first noted in the early 19th century, and was named after Sasso, Italy, where it was found. According to...
.
Properties
Boric acid was first prepared by
Wilhelm HombergWilhelm Homberg , also known as Guillaume Homberg in French, was a Dutch natural philosopher.-Life:...
(1652-1715) from
boraxBorax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...
, 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. 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 HBO
2. 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, H
2B
4O
7.
Boric acid can refer to any of these compounds. Further heating leads to
boron trioxideBoron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous form; however, it can be crystallized after extensive annealing...
.
Boric acid does not dissociate in
aqueous solutionAn aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant formula. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
, but is acidic due to its interaction with
waterWater is the most abundant molecule on Earth's surface, constituting about 70% of the planet's surface. In nature it exists in liquid, solid, and gaseous states. It is in dynamic equilibrium between the liquid and gas states at standard temperature and pressure. At room temperature, it is a nearly...
molecules to form the
tetrahydroxyborateTetrahydroxyborate, [H4BO4]− or B, is a boron oxoanion with a tetrahedral geometry.B is formed by the addition of hydroxide, OH−, to boric acid, B3:...
ion:
- B(OH)3 + H2O B(OH) + 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) + 2 H+ ⇌ B4O + 9 H2O
Boric acid makes an important contribution to the absorption of low frequency sound in seawater.
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.
|
|
| The unit cell of boric acid |
Hydrogen bond A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, like nitrogen, oxygen or fluorine . The hydrogen must be covalently bonded to another electronegative atom to create the bond...
ing (dashed lines)
allows boric acid molecules to form
parallel layers in the solid state |
Toxicology
Based on mammal median lethal dose (LD
50) 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. The Thirteenth Edition of the
Merck IndexThe Merck Index is an encyclopedia of chemicals, drugs and biologicals with over 10,000 monographs on single substances or groups of related compounds. It also includes an appendix with monographs on organic name reactions. It is published by the United States pharmaceutical company Merck & Co...
indicates that the LD
50 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 LD
50 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 atrophyTesticular atrophy is a medical condition in which the male reproductive organs diminish in size and may be accompanied by loss of function. This does not refer to temporary changes, such as those brought on by cold.Some medications can cause testicular atrophy...
after exposure to 32 mg/kg bw/day for 90 days. This level is far lower than the LD
50.
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. 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).
Medicinal
Boric acid can be used as an
antisepticAntiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
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
quartThe quart is an imperial and US customary unit of volume equal to a quarter of a gallon, two pints, or four cups. Since gallons of various sizes have historically been in use, quarts of various sizes have also existed...
(very close to a liter) of sterilised water. As an anti-bacterial compound, boric acid can also be used as an
acneAcne is a group of skin rashes that have different causes.* Acne vulgaris - most commonly experienced around puberty, typically of the face and shoulders/chest* Cystic acne, a severe form of acne wherein small cysts form...
treatment. Boric acid can be used to treat
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission...
and
fungal infectionsMycosis is a condition in which fungi pass the resistance barriers of the human or animal body and establish infections.-Classification:Mycoses are classified according to the tissue levels initially colonized:-Superficial mycoses:...
such as
candidiasisCandidiasis or thrush is a fungal infection of any of the Candida species, of which Candida albicans is the most common. Candidiasis encompasses infections that range from superficial, such as oral thrush and vaginitis, to systemic and potentially life-threatening diseases...
(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 footAthlete's foot is a fungal infection of the skin that causes scaling, flaking, and itch of affected areas. It is typically transmitted in moist areas where people walk barefoot, such as showers or bathhouses. Although the condition typically affects the feet, it can spread to other areas of the...
, by inserting powder in the socks or stockings, and in solution can be used to treat some kinds of
otitis externaOtitis externa is an inflammation of the outer ear and ear canal. Along with otitis media, external otitis is one of the two human conditions commonly called "earache". It also occurs in many other species. Inflammation of the skin of the ear canal is the essence of this disorder...
(ear infection) in both humans and animals. The preservative in
urineUrine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra. Cellular metabolism generates numerous waste compounds, many rich in nitrogen, that require elimination from the bloodstream...
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
cockroachCockroaches are insects of the order Blattaria. This name derives from the Latin name for the insect, Blatta....
es,
termiteThe termites are a group of eusocial insects usually classified at the taxonomic rank of order Isoptera . Along with ants and some bees and wasps which are all placed in the separate order Hymenoptera, termites divide labour among gender lines, produce overlapping generations and take care of...
s,
fire antFire ants are a variety of stinging ants with over 280 species worldwide. They have several common names including ginger ants and tropical fire ants , aka-kami-ari , fourmis de feu , Feuerameisen , and Langgam ....
s,
fleaFlea is the common name for insects of the order Siphonaptera which are wingless insects whose mouthparts are adapted for piercing skin and sucking blood....
s,
silverfishLepisma saccharina is a small, wingless insect typically measuring from a half to one inch...
, and many other
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s. It acts as a stomach poison affecting the insects'
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
, and the dry powder is
abrasiveAn abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...
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 H
3BO
3 films result from a spontaneous chemical reaction between water molecules and B
2O
3 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.
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 reactorPressurized water reactors comprise a majority of all western nuclear power plants and are one of two types of light water reactor , the other type being boiling water reactors . In a PWR the primary coolant is pumped under high pressure to the reactor core, then the heated water transfers...
s (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
annealingAnnealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the re-crystallization temperature and maintaining a suitable temperature,...
and
solderingSoldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point. Soft soldering is characterized by the melting point of the filler metal, which is below 400 °C...
operations.
Boric acid is used in producing the glasses of LCD
flat panel displayFlat panel displays encompass a growing number of technologies enabling video displays that are lighter and much thinner than traditional television and video displays that use cathode ray tubes, and are usually less than 4 inches thick...
s.
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 to
{{Chembox
| Watchedfields = changed
| verifiedrevid = 258855058
| ImageFileL1 = Boric-acid-2D.png
| ImageSizeL1 = 100px
| ImageFileR1 = Boric-acid-3D-balls.png
| ImageNameR1 = Boric acid
| ImageSizeR1=120px
| ImageFile2 = Boric acid.jpg
| ImageName2 = Boric acid
| ImageSize2 = 150px
| IUPACName = boric acid
trihydroxidoboron
| OtherNames = Orthoboric acid,
Boracic acid,
Sassolite,
Optibor,
Borofax
| Section1 = {{Chembox Identifiers
| CASNo = 10043-35-3
| CASNo_Ref = {{cascite}}
| SMILES = OB(O)O
| InChI=1/BH3O3/c2-1(3)4/h2-4H
| InChIKey = KGBXLFKZBHKPEV-UHFFFAOYAI
}}
| Section2 = {{Chembox Properties
| H = 3 | B = 1 | O = 3
| Appearance = White crystalline solid
| Density = 1.435 g/cm3
| Solubility = 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)
| SolubleOther = soluble in lower alcoholIn chemistry, an alcohol is any organic compound in which a hydroxyl group is bound to a carbon atom of an alkyl or substituted alkyl group. An important group of acohols is formed by the simple acyclic alcohols, the general formula for which is C
nH
2n+1OH...
s
moderately soluble in
pyridinePyridine is a simple aromatic heterocyclic organic compound with the chemical formula C
5H
5N used as a precursor to agrochemicals and pharmaceuticals, and is also an important solvent and reagent. It is structurally related to benzene, wherein one CH group in the aromatic...
very slightly soluble in
acetoneAcetone is the organic compound with the formula OC2. This colorless, mobile, flammable liquid is the simplest example of the ketones. Owing to the fact that acetone is miscible with water it serves as an important solvent in its own right, typically as the solvent of choice for...
| MeltingPt = 170.9 °C
| BoilingPt = 300 °C
| pKa = 9.24 (
see text)
}}
| Section3 = {{Chembox Structure
| MolShape = Trigonal planar
| Dipole = Zero
}}
| Section7 = {{Chembox Hazards
| EUClass = Toxic (
T)
Repr. Cat. 2
| RPhrases = {{R60}}, {{R61}}
| SPhrases = {{S53}}, {{S45}}
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
| FlashPt = Non-flammable.
| LD50 = 2660 mg/kg, oral (rat)
}}
| Section8 = {{Chembox Related
| OtherCpds =
Boron trioxideBoron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous form; however, it can be crystallized after extensive annealing...
BoraxBorax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...
}}
}}
Boric acid, also called
boracic acid or
orthoboric acid or
Acidum Boricum, is a weak
acidAn acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion activity greater than in pure water, i.e. a pH less than 7.0...
often used as an
antisepticAntiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
,
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
,
flame retardantFlame retardants are materials that inhibit or resist the spread of fire. These can be separated into several categories:*Minerals such as asbestos, compounds such as aluminium hydroxide, magnesium hydroxide, hydromagnesite, antimony trioxide, various hydrates, red phosphorus, and boron compounds,...
, in nuclear power plants to control the fission rate of
uraniumUranium is a silvery-white metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. Besides its 92 protons, a uranium nucleus can have between 141 and 146 neutrons. The most common uranium isotopes are U-238 and U-235 . A uranium atom has...
, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a white powder and dissolves in
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
. It has the
chemical formulaA chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
HHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
3BBoron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a trivalent metalloid element which occurs abundantly in the evaporite ores borax and ulexite....
OOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
3, sometimes written B(OH)
3. When occurring as a
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
, it is called
sassoliteSassolite is a borate mineral, and is the mineral form of boric acid. It occurs in volcanic fumaroles and hot springs, as well as in bedded sedimentary borate deposits. Its mineral form was first noted in the early 19th century, and was named after Sasso, Italy, where it was found. According to...
.
Properties
Boric acid was first prepared by
Wilhelm HombergWilhelm Homberg , also known as Guillaume Homberg in French, was a Dutch natural philosopher.-Life:...
(1652-1715) from
boraxBorax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...
, 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. 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 HBO
2. 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, H
2B
4O
7.
Boric acid can refer to any of these compounds. Further heating leads to
boron trioxideBoron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous form; however, it can be crystallized after extensive annealing...
.
Boric acid does not dissociate in
aqueous solutionAn aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant formula. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
, but is acidic due to its interaction with
waterWater is the most abundant molecule on Earth's surface, constituting about 70% of the planet's surface. In nature it exists in liquid, solid, and gaseous states. It is in dynamic equilibrium between the liquid and gas states at standard temperature and pressure. At room temperature, it is a nearly...
molecules to form the
tetrahydroxyborateTetrahydroxyborate, [H4BO4]− or B, is a boron oxoanion with a tetrahedral geometry.B is formed by the addition of hydroxide, OH−, to boric acid, B3:...
ion:
- B(OH)3 + H2O {{eqm}} B(OH){{su|b=4|p=−}} + 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){{su|b=4|p=−}} + 2 H+ ⇌ B4O{{su|b=7|p=2−}} + 9 H2O
Boric acid makes an important contribution to the absorption of low frequency sound in seawater.
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.
|
|
| The unit cell of boric acid |
Hydrogen bond A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, like nitrogen, oxygen or fluorine . The hydrogen must be covalently bonded to another electronegative atom to create the bond...
ing (dashed lines)
allows boric acid molecules to form
parallel layers in the solid state |
Toxicology
Based on mammal median lethal dose (LD
50) 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. The Thirteenth Edition of the
Merck IndexThe Merck Index is an encyclopedia of chemicals, drugs and biologicals with over 10,000 monographs on single substances or groups of related compounds. It also includes an appendix with monographs on organic name reactions. It is published by the United States pharmaceutical company Merck & Co...
indicates that the LD
50 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 LD
50 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 atrophyTesticular atrophy is a medical condition in which the male reproductive organs diminish in size and may be accompanied by loss of function. This does not refer to temporary changes, such as those brought on by cold.Some medications can cause testicular atrophy...
after exposure to 32 mg/kg bw/day for 90 days. This level is far lower than the LD
50.
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. 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).
Medicinal
Boric acid can be used as an
antisepticAntiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
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
quartThe quart is an imperial and US customary unit of volume equal to a quarter of a gallon, two pints, or four cups. Since gallons of various sizes have historically been in use, quarts of various sizes have also existed...
(very close to a liter) of sterilised water. As an anti-bacterial compound, boric acid can also be used as an
acneAcne is a group of skin rashes that have different causes.* Acne vulgaris - most commonly experienced around puberty, typically of the face and shoulders/chest* Cystic acne, a severe form of acne wherein small cysts form...
treatment. Boric acid can be used to treat
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission...
and
fungal infectionsMycosis is a condition in which fungi pass the resistance barriers of the human or animal body and establish infections.-Classification:Mycoses are classified according to the tissue levels initially colonized:-Superficial mycoses:...
such as
candidiasisCandidiasis or thrush is a fungal infection of any of the Candida species, of which Candida albicans is the most common. Candidiasis encompasses infections that range from superficial, such as oral thrush and vaginitis, to systemic and potentially life-threatening diseases...
(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 footAthlete's foot is a fungal infection of the skin that causes scaling, flaking, and itch of affected areas. It is typically transmitted in moist areas where people walk barefoot, such as showers or bathhouses. Although the condition typically affects the feet, it can spread to other areas of the...
, by inserting powder in the socks or stockings, and in solution can be used to treat some kinds of
otitis externaOtitis externa is an inflammation of the outer ear and ear canal. Along with otitis media, external otitis is one of the two human conditions commonly called "earache". It also occurs in many other species. Inflammation of the skin of the ear canal is the essence of this disorder...
(ear infection) in both humans and animals. The preservative in
urineUrine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra. Cellular metabolism generates numerous waste compounds, many rich in nitrogen, that require elimination from the bloodstream...
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
cockroachCockroaches are insects of the order Blattaria. This name derives from the Latin name for the insect, Blatta....
es,
termiteThe termites are a group of eusocial insects usually classified at the taxonomic rank of order Isoptera . Along with ants and some bees and wasps which are all placed in the separate order Hymenoptera, termites divide labour among gender lines, produce overlapping generations and take care of...
s,
fire antFire ants are a variety of stinging ants with over 280 species worldwide. They have several common names including ginger ants and tropical fire ants , aka-kami-ari , fourmis de feu , Feuerameisen , and Langgam ....
s,
fleaFlea is the common name for insects of the order Siphonaptera which are wingless insects whose mouthparts are adapted for piercing skin and sucking blood....
s,
silverfishLepisma saccharina is a small, wingless insect typically measuring from a half to one inch...
, and many other
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s. It acts as a stomach poison affecting the insects'
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
, and the dry powder is
abrasiveAn abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...
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
{{Refimprove|section|date=September 2009}}
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 H
3BO
3 films result from a spontaneous chemical reaction between water molecules and B
2O
3 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.
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 reactorPressurized water reactors comprise a majority of all western nuclear power plants and are one of two types of light water reactor , the other type being boiling water reactors . In a PWR the primary coolant is pumped under high pressure to the reactor core, then the heated water transfers...
s (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
annealingAnnealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the re-crystallization temperature and maintaining a suitable temperature,...
and
solderingSoldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point. Soft soldering is characterized by the melting point of the filler metal, which is below 400 °C...
operations.
Boric acid is used in producing the glasses of LCD
flat panel displayFlat panel displays encompass a growing number of technologies enabling video displays that are lighter and much thinner than traditional television and video displays that use cathode ray tubes, and are usually less than 4 inches thick...
s.
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 {{chem|H|3|BO|3}} to
{{Chembox
| Watchedfields = changed
| verifiedrevid = 258855058
| ImageFileL1 = Boric-acid-2D.png
| ImageSizeL1 = 100px
| ImageFileR1 = Boric-acid-3D-balls.png
| ImageNameR1 = Boric acid
| ImageSizeR1=120px
| ImageFile2 = Boric acid.jpg
| ImageName2 = Boric acid
| ImageSize2 = 150px
| IUPACName = boric acid
trihydroxidoboron
| OtherNames = Orthoboric acid,
Boracic acid,
Sassolite,
Optibor,
Borofax
| Section1 = {{Chembox Identifiers
| CASNo = 10043-35-3
| CASNo_Ref = {{cascite}}
| SMILES = OB(O)O
| InChI=1/BH3O3/c2-1(3)4/h2-4H
| InChIKey = KGBXLFKZBHKPEV-UHFFFAOYAI
}}
| Section2 = {{Chembox Properties
| H = 3 | B = 1 | O = 3
| Appearance = White crystalline solid
| Density = 1.435 g/cm3
| Solubility = 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)
| SolubleOther = soluble in lower alcoholIn chemistry, an alcohol is any organic compound in which a hydroxyl group is bound to a carbon atom of an alkyl or substituted alkyl group. An important group of acohols is formed by the simple acyclic alcohols, the general formula for which is C
nH
2n+1OH...
s
moderately soluble in
pyridinePyridine is a simple aromatic heterocyclic organic compound with the chemical formula C
5H
5N used as a precursor to agrochemicals and pharmaceuticals, and is also an important solvent and reagent. It is structurally related to benzene, wherein one CH group in the aromatic...
very slightly soluble in
acetoneAcetone is the organic compound with the formula OC2. This colorless, mobile, flammable liquid is the simplest example of the ketones. Owing to the fact that acetone is miscible with water it serves as an important solvent in its own right, typically as the solvent of choice for...
| MeltingPt = 170.9 °C
| BoilingPt = 300 °C
| pKa = 9.24 (
see text)
}}
| Section3 = {{Chembox Structure
| MolShape = Trigonal planar
| Dipole = Zero
}}
| Section7 = {{Chembox Hazards
| EUClass = Toxic (
T)
Repr. Cat. 2
| RPhrases = {{R60}}, {{R61}}
| SPhrases = {{S53}}, {{S45}}
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
| FlashPt = Non-flammable.
| LD50 = 2660 mg/kg, oral (rat)
}}
| Section8 = {{Chembox Related
| OtherCpds =
Boron trioxideBoron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous form; however, it can be crystallized after extensive annealing...
BoraxBorax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...
}}
}}
Boric acid, also called
boracic acid or
orthoboric acid or
Acidum Boricum, is a weak
acidAn acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion activity greater than in pure water, i.e. a pH less than 7.0...
often used as an
antisepticAntiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
,
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
,
flame retardantFlame retardants are materials that inhibit or resist the spread of fire. These can be separated into several categories:*Minerals such as asbestos, compounds such as aluminium hydroxide, magnesium hydroxide, hydromagnesite, antimony trioxide, various hydrates, red phosphorus, and boron compounds,...
, in nuclear power plants to control the fission rate of
uraniumUranium is a silvery-white metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. Besides its 92 protons, a uranium nucleus can have between 141 and 146 neutrons. The most common uranium isotopes are U-238 and U-235 . A uranium atom has...
, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a white powder and dissolves in
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
. It has the
chemical formulaA chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
HHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
3BBoron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a trivalent metalloid element which occurs abundantly in the evaporite ores borax and ulexite....
OOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
3, sometimes written B(OH)
3. When occurring as a
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
, it is called
sassoliteSassolite is a borate mineral, and is the mineral form of boric acid. It occurs in volcanic fumaroles and hot springs, as well as in bedded sedimentary borate deposits. Its mineral form was first noted in the early 19th century, and was named after Sasso, Italy, where it was found. According to...
.
Properties
Boric acid was first prepared by
Wilhelm HombergWilhelm Homberg , also known as Guillaume Homberg in French, was a Dutch natural philosopher.-Life:...
(1652-1715) from
boraxBorax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...
, 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. 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 HBO
2. 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, H
2B
4O
7.
Boric acid can refer to any of these compounds. Further heating leads to
boron trioxideBoron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous form; however, it can be crystallized after extensive annealing...
.
Boric acid does not dissociate in
aqueous solutionAn aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant formula. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
, but is acidic due to its interaction with
waterWater is the most abundant molecule on Earth's surface, constituting about 70% of the planet's surface. In nature it exists in liquid, solid, and gaseous states. It is in dynamic equilibrium between the liquid and gas states at standard temperature and pressure. At room temperature, it is a nearly...
molecules to form the
tetrahydroxyborateTetrahydroxyborate, [H4BO4]− or B, is a boron oxoanion with a tetrahedral geometry.B is formed by the addition of hydroxide, OH−, to boric acid, B3:...
ion:
- B(OH)3 + H2O {{eqm}} B(OH){{su|b=4|p=−}} + 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){{su|b=4|p=−}} + 2 H+ ⇌ B4O{{su|b=7|p=2−}} + 9 H2O
Boric acid makes an important contribution to the absorption of low frequency sound in seawater.
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.
|
|
| The unit cell of boric acid |
Hydrogen bond A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, like nitrogen, oxygen or fluorine . The hydrogen must be covalently bonded to another electronegative atom to create the bond...
ing (dashed lines)
allows boric acid molecules to form
parallel layers in the solid state |
Toxicology
Based on mammal median lethal dose (LD
50) 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. The Thirteenth Edition of the
Merck IndexThe Merck Index is an encyclopedia of chemicals, drugs and biologicals with over 10,000 monographs on single substances or groups of related compounds. It also includes an appendix with monographs on organic name reactions. It is published by the United States pharmaceutical company Merck & Co...
indicates that the LD
50 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 LD
50 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 atrophyTesticular atrophy is a medical condition in which the male reproductive organs diminish in size and may be accompanied by loss of function. This does not refer to temporary changes, such as those brought on by cold.Some medications can cause testicular atrophy...
after exposure to 32 mg/kg bw/day for 90 days. This level is far lower than the LD
50.
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. 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).
Medicinal
Boric acid can be used as an
antisepticAntiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
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
quartThe quart is an imperial and US customary unit of volume equal to a quarter of a gallon, two pints, or four cups. Since gallons of various sizes have historically been in use, quarts of various sizes have also existed...
(very close to a liter) of sterilised water. As an anti-bacterial compound, boric acid can also be used as an
acneAcne is a group of skin rashes that have different causes.* Acne vulgaris - most commonly experienced around puberty, typically of the face and shoulders/chest* Cystic acne, a severe form of acne wherein small cysts form...
treatment. Boric acid can be used to treat
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission...
and
fungal infectionsMycosis is a condition in which fungi pass the resistance barriers of the human or animal body and establish infections.-Classification:Mycoses are classified according to the tissue levels initially colonized:-Superficial mycoses:...
such as
candidiasisCandidiasis or thrush is a fungal infection of any of the Candida species, of which Candida albicans is the most common. Candidiasis encompasses infections that range from superficial, such as oral thrush and vaginitis, to systemic and potentially life-threatening diseases...
(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 footAthlete's foot is a fungal infection of the skin that causes scaling, flaking, and itch of affected areas. It is typically transmitted in moist areas where people walk barefoot, such as showers or bathhouses. Although the condition typically affects the feet, it can spread to other areas of the...
, by inserting powder in the socks or stockings, and in solution can be used to treat some kinds of
otitis externaOtitis externa is an inflammation of the outer ear and ear canal. Along with otitis media, external otitis is one of the two human conditions commonly called "earache". It also occurs in many other species. Inflammation of the skin of the ear canal is the essence of this disorder...
(ear infection) in both humans and animals. The preservative in
urineUrine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and excreted through the urethra. Cellular metabolism generates numerous waste compounds, many rich in nitrogen, that require elimination from the bloodstream...
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
cockroachCockroaches are insects of the order Blattaria. This name derives from the Latin name for the insect, Blatta....
es,
termiteThe termites are a group of eusocial insects usually classified at the taxonomic rank of order Isoptera . Along with ants and some bees and wasps which are all placed in the separate order Hymenoptera, termites divide labour among gender lines, produce overlapping generations and take care of...
s,
fire antFire ants are a variety of stinging ants with over 280 species worldwide. They have several common names including ginger ants and tropical fire ants , aka-kami-ari , fourmis de feu , Feuerameisen , and Langgam ....
s,
fleaFlea is the common name for insects of the order Siphonaptera which are wingless insects whose mouthparts are adapted for piercing skin and sucking blood....
s,
silverfishLepisma saccharina is a small, wingless insect typically measuring from a half to one inch...
, and many other
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
s. It acts as a stomach poison affecting the insects'
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
, and the dry powder is
abrasiveAn abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...
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
{{Refimprove|section|date=September 2009}}
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 H
3BO
3 films result from a spontaneous chemical reaction between water molecules and B
2O
3 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.
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 reactorPressurized water reactors comprise a majority of all western nuclear power plants and are one of two types of light water reactor , the other type being boiling water reactors . In a PWR the primary coolant is pumped under high pressure to the reactor core, then the heated water transfers...
s (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
annealingAnnealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the re-crystallization temperature and maintaining a suitable temperature,...
and
solderingSoldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point. Soft soldering is characterized by the melting point of the filler metal, which is below 400 °C...
operations.
Boric acid is used in producing the glasses of LCD
flat panel displayFlat panel displays encompass a growing number of technologies enabling video displays that are lighter and much thinner than traditional television and video displays that use cathode ray tubes, and are usually less than 4 inches thick...
s.
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 {{chem|H|3|BO|3}} to
{{chemNickel sulfate, or just nickel sulfate, usually refers to the chemical compound with the formula NiSO
4. This highly soluble blue-coloured salt is a common source of the Ni
2+ ion for electroplating....
, a very small portion of sodium lauryl sulfate and a small portion of
{{chemSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
.
It is also used in the manufacturing of remming mass, a fine silica-containing powder used for producing
induction furnaceAn induction furnace is an electrical furnace in which the heat is applied by induction heating of a conductive medium in a crucible placed in a water-cooled alternating current solenoid coil. The advantage of the induction furnace is a clean, energy-efficient and well-controllable melting process...
linings and
ceramicA ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
s.
Miscellaneous
BorateBorates in chemistry are chemical compounds containing boron oxoanions, with boron in oxidation state +3. The simplest borate ion is the trigonal planar, BO33−, although many others are known. BO33− forms salts with metallic elements. Boron found in...
s including boric acid have been used since the time of the
GreekAncient Greece is the civilisation belonging to the period of Greek history lasting from the Greek Dark Ages ca. 1100 BC and the Dorian invasion, to 146 BC and the Roman conquest of Greece after the Battle of Corinth. It is generally considered to be the seminal culture which provided the...
s for cleaning, preserving food, and other activities.{{Citation needed|date=December 2007}}
Silly PuttySilly Putty is the Crayola owned trademark name for a class of silicone polymers...
was originally made by adding boric acid to
silicone oilSilicone oils are silicon analogues of carbon based organic compounds, and can form long and complex molecules based on silicon rather than carbon. Chains are formed of alternating silicon-oxygen atoms or siloxane, rather than carbon atoms...
.
TBE bufferTBE or Tris/Borate/EDTA, is a buffer solution containing a mixture of Tris base, boric acid and EDTA.In molecular biology, TBE and TAE buffers are often used in procedures involving nucleic acids, the most common being electrophoresis. Tris-acid solutions are effective buffers for slightly basic...
is widely used for the
electrophoresisElectrophoresis is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. This electrokinetic phenomenon was observed for the first time in 1807 by Reuss , who noticed that the application of a constant electric field caused clay particles...
of
nucleic acidA nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within cells. The most common nucleic acids are deoxyribonucleic acid and ribonucleic acid . Nucleic acids are universal in living things, as...
s and has a higher buffer capacity than a
TAE bufferTAE buffer is a buffer solution containing a mixture of Tris base, acetic acid and EDTA.In molecular biology it is used in agarose electrophoresis typically for the separation of nucleic acids such as DNA and RNA. It is made up of Tris-acetate buffer, usually at pH 8.0, and EDTA, which sequesters...
. It can be used for
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
and
RNARibonucleic acid is a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate...
polyacrylamidePolyacrylamide is a polymer formed from acrylamide subunits that can also be readily cross-linked. Acrylamide needs to be handled using best laboratory practice Polyacrylamide (IUPAC poly(2-propenamide) or poly(1-carbamoylethylene)) is a polymer (-CH2CHCONH2-) formed from...
and
agarose gel electrophoresisAgarose gel electrophoresis is a method used in biochemistry and molecular biology to separate DNA, or RNA molecules by size. This is achieved by moving negatively charged nucleic acid molecules through an agarose matrix with an electric field...
.
It is used in
pyrotechnicsPyrotechnics is the science of materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...
to prevent the
amideIn chemistry, an amide is usually an organic compound that contains the functional group consisting of an acyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds...
-forming reaction between
aluminiumAluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13. It is not soluble in water under normal circumstances....
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
methanolMethanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with formula CH3OH . It is toxic: drinking 10 ml will cause blindness, and as little as 100 ml will cause death...
is popularly used among fire jugglers and fire spinners to create a deep green flame.
The white powder is also used in
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
and across the world to dust down
CarromCarrom or carroms is a family of tabletop games sharing a similarity in that their mechanics lie somewhere between billiards and table shuffleboard...
boards to decrease friction and increase speed of play.
Boric acid is added to salt in the curing of cattle hides,
calfskinCalfskin is a leather or membrane produced from the hide of a calf. Calfskin is particularly valuable because of its softness, and fine grain. It is commonly used for high-quality shoes, wallets and similar products, as well as traditional leather bookbindings...
s and
sheepskinSheepskin is the hide of a sheep, sometimes also called lambskin or lambswool.Sheepskin may also refer to:* Parchment, a thin material made from calfskin, sheepskin or goatskin** Diploma, originally made of sheepskin...
s. Used in that way it helps to control bacteria development and also aids in the control of insects.
External links
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