View source for Boric acid

{{short description|Weak acid with formula B(OH)₃}}
{{Use dmy dates|date=February 2023}}
{{Chembox
|Watchedfields  = changed
|verifiedrevid  = 476995365
|ImageFileL1_Ref = {{chemboximage|correct|??}}
|Name = Orthoboric acid
|ImageFileL1 = Boric-acid-2D.png
|ImageNameL1 = Structural formula
|ImageFileR1 = Boric-acid-3D-vdW.png
|ImageNameR1 = Space-filling model
|ImageFile2 = Boric acid.jpg
|ImageName2 = Boric acid crystals
|IUPACName = Boric acid<ref name=ncbi/>
|OtherNames = Orthoboric acid, Boracic acid, Sassolite, Borofax, Trihydroxyborane, Boranetriol, Hydrogen borate, ''Acidum boricum''
|Section1 = {{Chembox Identifiers
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 7346
|PubChem = 7628
|SMILES1 = [OH+]=[B-](O)O
|ChEMBL_Ref = {{ebicite|correct|EBI}}
|ChEMBL = 42403
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/BH3O3/c2-1(3)4/h2-4H
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = KGBXLFKZBHKPEV-UHFFFAOYSA-N
|CASNo = 10043-35-3
|CASNo_Ref = {{cascite|correct|CAS}}
|ChEBI_Ref = {{ebicite|correct|EBI}}
|ChEBI = 33118
|SMILES = OB(O)O
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = R57ZHV85D4
|KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = D01089
|InChI=1/BH3O3/c2-1(3)4/h2-4H
|InChIKey = KGBXLFKZBHKPEV-UHFFFAOYAI
|EINECS = 233-139-2
}}
|Section2 = {{Chembox Properties
|H=3 | B=1 | O=3
|Appearance = White crystalline solid
|Density = 1.435 g/cm<sup>3</sup>
|Solubility = 2.52 g/100 mL (0&nbsp;°C) <br /> 4.72 g/100 mL (20&nbsp;°C) <br /> 5.7 g/100 mL (25&nbsp;°C) <br /> 19.10 g/100 mL (80&nbsp;°C) <br /> 27.53 g/100 mL (100&nbsp;°C)
|SolubleOther = Soluble in lower [[Alcohol (chemistry)|alcohol]]s <br /> moderately soluble in [[pyridine]] <br /> very slightly soluble in [[acetone]]
|Solvent = other solvents
|MeltingPtC = 170.9
|BoilingPtC = 300
|ConjugateBase = [[Borate]]
|pKa = {{awrap|9.24 ([[Acid_dissociation_constant#Polyprotic_acids|first proton]]),}} {{awrap|12.4 (second),}} {{awrap|13.3 (complete)}}
|MagSus = -34.1·10<sup>−6</sup> cm<sup>3</sup>/mol
|LogP = -0.29<ref name=chemsrc/>
}}
|Section3 = {{Chembox Structure
|MolShape = Trigonal planar
|Dipole = 0 D
}}
|Section4 = {{Chembox Pharmacology
|ATCCode_prefix = S02
|ATCCode_suffix = AA03
|ATC_Supplemental = {{ATC|D08|AD}}
}}
|Section5 = {{Chembox Hazards
|GHSPictograms = {{GHS08}}
|NFPA-H = 1
|NFPA-F = 0
|NFPA-R = 0
|FlashPt = Nonflammable
|LD50 = 2660 mg/kg, oral (rat)
}}
|Section6 = {{Chembox Related
|OtherCompounds = [[Boron trioxide]]<br />[[Borax]]}}
}}

'''Boric acid''', more specifically '''orthoboric acid''', is a compound of [[boron]], [[oxygen]], and [[hydrogen]] with formula {{chem2|B(OH)3}}. It may also be called '''hydrogen [[orthoborate]]''', '''trihydroxidoboron''' or '''boracic acid'''.<ref name=webster/> It is usually encountered as colorless crystals or a white powder, that dissolves in [[water]], and occurs in nature as the mineral [[sassolite]].   It is a weak [[acid]] that yields various [[borate]] [[anion]]s and [[salt (chemistry)|salts]], and can react with [[Alcohol (chemistry)|alcohol]]s to form [[borate ester]]s.

Boric acid is often used as an [[antiseptic]], [[insecticide]], [[flame retardant]], [[neutron absorber]], or precursor to other boron compounds.

The term "boric acid" is also used generically for any [[oxoacid]] of boron, such as [[metaboric acid]] {{chem2|HBO2}} and [[tetraboric acid]] {{chem2|H2B4O7}}.

==History==
Orthoboric acid was first prepared by [[Wilhelm Homberg]] (1652–1715) from [[borax]], by the action of mineral acids, and was given the name {{lang|la|sal sedativum Hombergi}} ("sedative salt of Homberg"). However boric acid and [[borate]]s have been used since the time of the [[ancient Greece|ancient Greek]]s for cleaning, preserving food, and other activities.<ref name=eisler2007/>

==Molecular and crystal structure==
The three oxygen atoms form a [[Trigonal planar molecular geometry|trigonal planar geometry]] around the boron. The B-O bond length is 136 pm and the O-H is 97 pm. The [[molecular symmetry|molecular point group]] is ''C''<sub>3h</sub>.<ref>{{Greenwood&Earnshaw2nd|page=1291}}</ref>

Two crystalline forms of orthoboric acid are known: [[triclinic crystal system|triclinic]] with [[space group]] P{{overline|1}}, and [[hexagonal crystal system|trigonal]] with space group P3<sub>2</sub>. The former is the most common; the second, which is a bit more stable thermodynamically, can be obtained with a special preparation method.<ref name=rota2017/>

The triclinic form of boric acid consists of layers of {{chem2|B(OH)3}} molecules held together by hydrogen bonds with an O...O separation of 272 pm. The distance between two adjacent layers is 318 pm.<ref name=GandE/> While the layers of the triclinic phase are nearly trigonal with {{nowrap|1=γ = 119.76°}}, {{nowrap|1=''a'' = 701.87 pm}}, and {{nowrap|1=''b'' = 703.5 pm}} (compared to {{nowrap|1=''a'' = 704.53(4) pm}} for the trigonal form), the stacking of the layers is somewhat offset in the triclinic phase, with {{nowrap|1=α = 92.49°}} and {{nowrap|1=β = 101.46°}}. The triclinic phase has {{nowrap|1=''c'' = 634.72 pm}} and the trigonal one has {{nowrap|1=''a'' = 956.08(7) pm}}.<ref>{{cite journal |last1=Gajhede |first1=M. |last2=Larsen |first2=S. |last3=Rettrup |first3=S. |title=Electron density of orthoboric acid determined by X-ray diffraction at 105 K and ab initio calculations |journal=Acta Crystallographica Section B Structural Science |date=1 December 1986 |volume=42 |issue=6 |pages=545–552 |doi=10.1107/S0108768186097720 |bibcode=1986AcCrB..42..545G |url=https://www.crystallography.net/cod/9007675.html}}</ref><ref>{{cite journal |last1=Shuvalov |first1=Robert R. |last2=Burns |first2=Peter C. |title=A new polytype of orthoboric acid, H 3 BO 3 -3 T |journal=Acta Crystallographica Section C Crystal Structure Communications |date=15 June 2003 |volume=59 |issue=6 |pages=i47–i49 |doi=10.1107/S0108270103009685|pmid=12794317 |bibcode=2003AcCrC..59I..47S }}</ref>

{| style="margin:auto;" class="wikitable"
|[[File:Boric-acid-unit-cell-3D-balls.png|center|200px]]||[[File:Boric-acid-layer-3D-balls.png|center|250px]]
|-
|{{center|The [[unit cell]] of boric acid}}||{{center|[[hydrogen bond]]ing (dashed lines)<br />allows boric acid molecules to form<br />parallel layers in the solid state}}
|}

==Preparation==
Boric acid may be prepared by reacting [[borax]] (sodium tetraborate decahydrate) with a [[mineral acid]], such as [[hydrochloric acid]]:

: {{chem2|Na2B4O7}}·10{{chem2|H2O}} + 2 HCl → 4 {{chem2|B(OH)3}} + 2 NaCl + 5 {{chem2|H2O}}

It is also formed as a by product of hydrolysis of boron trihalides and [[diborane]]:<ref name=hous2008/>

: {{chem2|B2H6}} + 6 {{chem2|H2O}} → 2 {{chem2|B(OH)3}} + 6 {{chem2|H2}}

: {{chem2|BX3}} + 3 {{chem2|H2O}} → {{chem2|B(OH)3}} + 3 HX (X = Cl, Br, I)

==Reactions==
===Pyrolysis===
When heated, orthoboric acid undergoes a three step dehydration. The reported transition temperatures vary substantially from source to source.{{cn|date=September 2023}}

When heated above 140&nbsp;°C, orthoboric acid yields [[metaboric acid]] ({{chem2|HBO2}}) with loss of one water molecule:<ref name=kaur2021/><ref name=aghi2018/>

: {{chem2|B(OH)3}} → {{chem2|HBO2}} + {{chem2|H2O}}

Heating metaboric acid above about 180&nbsp;°C eliminates another water molecule forming [[tetraboric acid]], also called pyroboric acid ({{chem2|H2B4O7}}):<ref name=kaur2021/><ref name=aghi2018/>

: 4 {{chem2|HBO2}} → {{chem2|H2B4O7}} + {{chem2|H2O}}

Further heating (to about 530&nbsp;°C) leads to [[boron trioxide]]:<ref name=balci2012/><ref name=kaur2021/><ref name=aghi2018/>

: {{chem2|H2B4O7}} → 2 {{chem2|B2O3}} + {{chem2|H2O}}

===Aqueous solution===
When orthoboric acid is dissolved in water, it partially dissociates to give [[metaboric acid]]:
: {{chem2|B(OH)3}} {{Eqm}}  {{chem2|HBO2}} + {{chem2|H2O}}
The solution is mildly acidic due to ionization of the acids:
: {{chem2|B(OH)3}} + {{chem2|H2O}} {{Eqm}} {{chem2|[BO(OH)2]-}} + {{H3O+}}
: {{chem2|HBO2}} + {{chem2|H2O}} {{Eqm}} {{chem2|[BO2]-}} + {{H3O+}}

However, [[Raman spectroscopy]] of strongly alkaline solutions has shown the presence of [[tetrahydroxyborate|{{chem2|[B(OH)4]−}} ions]],<ref name=jolly1984/> leading some to conclude that the acidity is exclusively due to the abstraction of {{chem2|OH-}} from water:<ref name=jolly1984/>
:{{chem2|B(OH)3}} + {{chem2|HO-}} {{Eqm}} {{chem2|B(OH)4-}}
Equivalently,
:{{chem2|B(OH)3}} + {{chem2|H2O}} {{Eqm}} {{chem2|B(OH)4-}} + {{H+}} (''K''<sub>a</sub> = 7.3×10<sup>−10</sup>; p''K''<sub>a</sub> = 9.14)
Or, more properly,
:{{chem2|B(OH)3}} + 2 {{chem2|H2O}} {{Eqm}} {{chem2|B(OH)4-}} + {{H3O+}}
This reaction occurs in two steps, with the neutral complex aquatrihydroxyboron {{chem2|B(OH)3(OH2)}} as an intermediate:<ref name=tachi2004/>
#{{chem2|B(OH)3}} + {{chem2|H2O}} → {{chem2|B(OH)3(OH2)}}
#{{chem2|B(OH)3(OH2)}} + {{chem2|H2O}} → {{chem2|[B(OH)4]-}} + {{H3O+}}

This reaction may be characterized as [[Lewis acid]]ity of boron toward {{chem2|HO-}}, rather than as [[Brønsted acid]]ity.<ref name=hous2005/><ref name=JEE2014/><ref name=darp2000/> However, some of its behaviour towards some chemical reactions suggest it to be a tribasic acid in the Brønsted-Lowry sense as well.

Boric acid, mixed with [[borax]] {{chem2|Na2B4O7*10H2O}} (more properly {{chem2|Na2B4O5(OH)4*8H2O}}) in the weight ratio of 4:5, is highly soluble in water, though they are not so soluble separately.<ref name=tsuy2007/>

===Sulfuric acid solution===
Boric acid also dissolves in anhydrous sulfuric acid according to the equation:<ref name=GandE/>
:{{chem2|B(OH)3}} + 6 {{chem2|H2SO4}} → {{chem2|[B(SO4H)4]-}} + 2 {{chem2|[HSO4]-}} + 3 {{H3O+}}
The product is an extremely strong acid, even stronger than the original sulfuric acid.<ref name=GandE/>

===Esterification===
Boric acid reacts with alcohols to form [[borate ester]]s, {{chem2|B(OR)3}} where R is [[alkyl]] or [[aryl]]. The reaction is typically driven by a dehydrating agent, such as concentrated [[sulfuric acid]]:<ref name=brown1956/>

:{{chem2|B(OH)3}} + 3 ROH → {{chem2|B(OR)3}} + 3 {{chem2|H2O}}

===With vicinal diols===
The acidity of boric acid solutions is greatly increased in the presence of [[cis–trans isomerism|cis]]-[[diol#Vicinal diols|vicinal diols]] ([[organic compound]]s containing similarly oriented [[hydroxyl]] groups in adjacent [[carbon]] atoms, {{chem2|(R1,R2)\dC(OH)\sC(OH)\d(R3,R4)}}) such as [[glycerol]] and [[mannitol]].<ref name=vogelP357/><ref name=GandE/><ref name=NIST1969/>

The tetrahydroxyborate anion formed in the dissolution spontaneously reacts with these diols to form relatively stable anion esters containing one or two five-member {{chem2|\sB\sO\sC\sC\sO\s}} rings. For example, the reaction with mannitol {{chem2|H(HCOH)6H}}, whose two middle hydroxyls are in ''cis'' orientation, can be written as
: {{chem2|B(OH)3}} + {{chem2|H2O}} {{Eqm}} {{chem2|[B(OH)4]-}} + {{chem2|H+}} 
: {{chem2|[B(OH)4]-}} + {{chem2|H(HCOH)6H}} {{Eqm}} {{chem2|[B(OH)2(H(HCOH)2(HCO\s)2(HCOH)2H)]-}} + 2 {{chem2|H2O}} 
: {{chem2|[B(OH)2(H(HCOH)2(HCO\s)2(HCOH)2H)]-}} + {{chem2|H(HCOH)6H}} {{Eqm}} {{chem2|[B(H(HCOH)2(HCO\s)2(HCOH)2H)2]-}} + 2 {{chem2|H2O}}
Giving the overall reaction 
: {{chem2|B(OH)3}} + 2 {{chem2|H(HCOH)6H}} {{Eqm}} {{chem2|[B(H(HCOH)2(HCO\s)2(HCOH)2H)2]-}} + 3 {{chem2|H2O}} + {{chem2|H+}}

The stability of these [[mannitoborate]] ester anions shifts the equilibrium of the right and thus increases the acidity of the solution by 5 orders of magnitude compared to that of pure boric oxide, lowering the p''K''<sub>a</sub> from 9 to below 4 for sufficient concentration of mannitol.<ref name=vogelP357/><ref name=GandE/><ref name=NIST1969/> The resulting solution has been called [[mannitoboric acid]].

The addition of mannitol to an initially neutral solution containing boric acid or simple borates lowers its [[pH]] enough for it to be titrated by a strong base as NaOH, including with an automated a potentiometric [[titrator]].  This property is used in analytical chemistry to determine the borate content of aqueous solutions, for example to monitor the depletion of boric acid by [[neutron]]s in the water of the primary circuit of [[light-water reactor]] when the compound is added as a [[neutron poison]] during refueling operations.<ref name=GandE/>

==Toxicology==
Based on mammalian [[median lethal dose]] (LD<sub>50</sub>) rating of 2,660&nbsp;mg/kg body mass, boric acid is only poisonous if taken internally or inhaled in large quantities. The Fourteenth Edition of the ''[[Merck Index]]'' indicates that the LD<sub>50</sub> of boric acid is 5.14&nbsp;g/kg for oral dosages given to rats, and that 5 to 20&nbsp;g/kg has produced death in adult humans. For a 70&nbsp;kg adult, at the lower 5&nbsp;g/kg limit, 350&nbsp;g could produce death in humans. For comparison's sake, the LD<sub>50</sub> of [[sodium chloride|salt]] is reported to be 3.75&nbsp;g/kg in rats according to the ''Merck Index''. According to the [[Agency for Toxic Substances and Disease Registry]], "The minimal lethal dose of ingested boron (as boric acid) was reported to be 2–3&nbsp;g in infants, 5–6&nbsp;g in children, and 15–20&nbsp;g in adults. [...] However, a review of 784 human poisonings with boric acid (10–88&nbsp;g) reported no fatalities, with 88% of cases being asymptomatic."<ref name=HHS2010/>

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 reported [[testicular atrophy]] after exposure to 32&nbsp;mg/(kg⋅day) for 90&nbsp;days. This level, were it applicable to humans at like dose, would equate to a cumulative dose of 202&nbsp;g over 90&nbsp;days for a 70&nbsp;kg adult, not far lower than the above LD<sub>50</sub>.<ref name=FQPA2006/>

According to the CLH report for boric acid published by the Bureau for Chemical Substances Lodz, Poland, boric acid in high doses shows significant developmental toxicity and [[teratogenicity]] in rabbit, rat, and mouse fetuses, as well as cardiovascular defects, skeletal variations, and mild kidney lesions.<ref name=CLH2018/> As a consequence in the 30th ATP to EU directive 67/548/EEC of August 2008, the European Commission<!--EC--> decided to amend its classification as [[reprotoxic]] category&nbsp;2 and to apply the [[risk phrase]]s R60 (may impair fertility) and R61 (may cause harm to the unborn child).<ref name=BYU2008/><ref name=ishii1993/><ref name=rest1992/><ref name=duld2009/><ref name=NSWFA2009/>

At a 2010 European Diagnostics Manufacturing Association (EDMA) Meeting, several new additions to the [[substance of very high concern]] (SVHC) candidate list in relation to the [[Registration, Evaluation, Authorisation and Restriction of Chemicals]] Regulations 2007 (REACH) were discussed. Following the registration and review completed as part of REACH, the classification of boric acid CAS 10043-35-3 / 11113-50-1 is listed from 1&nbsp;December 2010 is ''H360FD (May damage fertility. May damage the unborn child)''.<ref name=ECHA2010/><ref name=EUP2008/>

==Uses==
===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.<ref name=kist1994/>

In the jewelry industry, boric acid is often used in combination with [[denatured alcohol]] to reduce surface [[oxidation]] and formation of [[firescale]] on metals during [[annealing (metallurgy)|annealing]] and [[soldering]] operations.<ref>{{Cite book |last=Hettmansperger |first=Mary |url=https://books.google.com/books?id=tV4eh7W01y8C&dq=%2522boric+acid%2522+firescale&pg=PA33 |title=Wrap, Stitch, Fold & Rivet: Making Designer Metal Jewelry |date=2008 |publisher=Lark Books |isbn=978-1-60059-125-9 |language=en}}</ref><ref>{{cite web|url=https://www.ganoksin.com/article/dealing-fire-scale/|website=Ganoksin Jewelry Making Resources|first=Charles|last=Lewton-Brain|title=Dealing with Fire Scale|access-date=20 June 2024}}</ref>

Boric acid is used in the production of the glass in [[liquid crystal display|LCD]] [[flat panel display]]s.<ref>{{cite web|url=https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Technical-Bulletin/borates-glasses.pdf?ext=.pdf|website=Borax|title=Technical Bulletin: Borates in glasses|year=2021}}</ref><ref>{{cite magazine|url=https://borates.today/boron-flat-panel-displays/|title=Boron Flat Panel Displays|date=9 February 2022|magazine=Borates Today}}</ref>

In [[electroplating]], boric acid is used as part of some proprietary formulas. One known formula uses about a 1 to 10 ratio of {{chem|H|3|BO|3}} to [[nickel(II) sulfate|{{chem|NiSO|4}}]], a very small portion of [[sodium lauryl sulfate]] and a small portion of [[sulfuric acid|{{chem|H|2|SO|4}}]].

The solution of orthoboric acid and borax in 4:5 ratio is used as a [[Fire retardant|fire retarding agent]] of wood by impregnation.<ref name=tsuy2009/>

It is also used in the manufacturing of [[ramming mass]], a fine [[silica]]-containing powder used for producing [[induction furnace]] linings and [[ceramic]]s.

Boric acid is added to [[borax]] for use as [[welding]] [[flux (metallurgy)|flux]] by [[blacksmith]]s.<ref name=demp2010/>

Boric acid, in combination with [[polyvinyl alcohol]] (PVA) or [[silicone oil]], is used to manufacture [[Silly Putty]].<ref name=silly2013/>

Boric acid is also present in the list of chemical additives used for [[hydraulic fracturing]] (fracking) in the [[Marcellus Shale]] in Pennsylvania.<ref name=PDEP2010/> It is often used in conjunction with [[guar gum]] as [[cross-link]]ing and gelling agent for controlling the [[viscosity]] and the rheology of the fracking fluid injected at high pressure in the well. It is important to control the fluid viscosity for keeping in suspension on long transport distances the grains of the [[Hydraulic fracturing proppants|propping agents]] aimed at maintaining the cracks in the [[shale]]s sufficiently open to facilitate the gas extraction after the hydraulic pressure is relieved.<ref name=fink2015/><ref name=bish2004/><ref name=EUP3004279/> The rheological properties of borate cross-linked guar gum [[hydrogel]] mainly depend on the [[pH]] value.<ref name=wang2016/>

Boric acid is used in some [[Fuse (electrical)#Expulsion fuses|expulsion-type electrical fuses]] as a de-ionization/extinguishing agent.<ref>{{Cite book |url=https://mcemalta.com/pdfs/Eaton%203PS%20Vol%2014.pdf |title=Electrical Sector Solutions Product Overview |publisher=[[Eaton Corporation]] |year=2011 |volume=14: Fuses}}</ref> During an [[electrical fault]] in an expulsion-type fuse, a [[Plasma (physics)|plasma]] arc is generated by the disintegration and rapid [[Spring (device)|spring]]-loaded separation of the fusible element, which is typically a specialized metal rod that passes through a compressed mass of boric acid within the fuse assembly. The high-temperature plasma causes the boric acid to rapidly decompose into [[water vapor]] and [[Boron trioxide|boric anhydride]], and in-turn, the vaporization products de-ionize the plasma, helping to interrupt the electrical fault.<ref>{{Cite journal |last1=Strom |first1=A. P. |last2=Rawlins |first2=H. L. |date=December 1932 |title=The Boric Acid Fuse |url=https://ieeexplore.ieee.org/document/5056215 |journal=Transactions of the American Institute of Electrical Engineers |volume=51 |issue=4 |pages=1020–1025 |doi=10.1109/T-AIEE.1932.5056215 |s2cid=51650608 |issn=0096-3860}}</ref>

===Medical===
Boric acid can be used as an [[antiseptic]] for minor burns or cuts and is sometimes used in salves and [[medical dressing|dressings]], such as [[boracic lint]]. Boric acid is applied in a very dilute solution as an eye wash. Boric acid [[Intravaginal administration|vaginal suppositories]] can be used for recurrent [[candidiasis]] due to non-albicans candida as a second line treatment when conventional treatment has failed.<ref name="iava2010" /><ref name=aber2010/> It is less effective than conventional treatment overall.<ref name="iava2010" /> Boric acid largely spares [[lactobacilli]] within the vagina.<ref name=sobel2021/> As [[TOL-463]], it is under development as an [[vaginal administration|intravaginal]] medication for the treatment for [[vulvovaginal candidiasis]].<ref name=adisTOL463/><ref name=nyir2022/><ref name=marra2019/> 

As an [[antibacterial]] compound, boric acid can also be used as an [[acne]] treatment. It is also used as prevention of [[athlete's foot]], by inserting powder in the socks or stockings. Various preparations can be used to treat some kinds of {{lang|la|[[otitis externa]]}} (ear infection) in both humans and animals.<ref name="adriz2018" /> The preservative in [[urine]] sample bottles in the UK is boric acid.<ref>{{Cite book |url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/636410/U_3i1.pdf |title=UK standards for microbiology investigations |publisher=[[Public Health England]] |date=2017-08-07}}</ref>

Boric acid solutions used as an eye wash or on abraded skin are known to be toxic, particularly to infants, especially after repeated use; this is because of its slow elimination rate.<ref name=harv1980/>

Boric acid is one of the most commonly used substances that can counteract the harmful effects of reactive [[hydrofluoric acid]] (HF) after an accidental contact with the skin. It works by forcing the free {{chem2|F-}} anions into the inert [[tetrafluoroborate]] anion. This process defeats the extreme toxicity of hydrofluoric acid, particularly its ability to [[chelation|sequester]] [[Calcium in biology|ionic calcium]] from [[Serum (blood)|blood serum]] which can lead to [[cardiac arrest]] and bone decomposition; such an event can occur from just minor skin contact with HF.<ref name=EPA2015/>{{Failed verification|date=July 2023}}

===Insecticidal===
Boric acid was first registered in the US as an insecticide in 1948 for control of [[cockroach]]es, [[termite]]s, [[fire ant]]s, [[flea]]s, [[silverfish]], and many other [[insect]]s. The product is generally considered to be safe to use in household kitchens to control cockroaches and ants.  It acts as a stomach poison affecting the insects' [[metabolism]], and the dry powder is [[abrasive]] to the insects' [[exoskeleton]]s.<ref name=ABC/><ref name=boone/><ref name=REDF2022/> Boric acid also has the reputation as "the gift that keeps on killing" in that cockroaches that cross over lightly dusted areas do not die immediately, but that the effect is like shards of glass cutting them apart. This often allows a roach to go back to the nest where it soon dies. Cockroaches, being [[Cannibalism (zoology)|cannibalistic]], eat others killed by contact or consumption of boric acid, consuming the powder trapped in the dead roach and killing them, too.{{citation needed|date=July 2020}}

Boric acid has also been widely used in the treatment of wood for protection against termites. The full complexity of its mechanism is not fully understood, but aside from causing dose-dependent mortality, boric acid causes [[dysbiosis]] in the [[Reticulitermes flavipes|Eastern Subterranean termite]], leading to the opportunistic rise of insect pathogens that could be contributing to mortality.<ref>{{Cite journal |url=https://academic.oup.com/jee/advance-article/doi/10.1093/jee/toae221/7821517 |access-date=2024-10-21 |journal=Journal of Economic Entomology |doi=10.1093/jee/toae221 |title=Lethal disruption of the bacterial gut community in Eastern subterranean termite caused by boric acid |date=2024 |last1=Ashbrook |first1=Aaron R. |last2=Schwarz |first2=Melbert |last3=Schal |first3=Coby |last4=Mikaelyan |first4=Aram |pmid=39401329 |doi-access=free }}</ref> 

===Preservation===
In combination with its use as an insecticide, boric acid 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. Concentrates of borate-based treatments can be used to prevent slime, mycelium, and algae growth, even in marine environments.{{citation needed|date=June 2022}}

Boric acid is added to salt in the curing of cattle hides, [[calfskin]]s, and [[sheepskin]]s. This helps to control bacterial development, and helps to control insects.{{citation needed|date=June 2022}}

===pH buffer===
[[File:Borate pH.gif|thumb|alt=Distribution between boric acid and borate ion versus pH assuming p''K''{{sub|a}} = 9.0 (e.g. salt-water swimming pool)|Boric acid predominates in solution below pH 9]]
[[File:Borate buffer.gif|thumb|alt=Buffer capacity of the boric acid - borate system versus pH assuming p''K''{{sub|a}} = 9.0 (e.g. salt-water swimming pool)|Boric acid buffers against rising pH in swimming pools]]
Boric acid in equilibrium with its conjugate base the borate ion is widely used (in the concentration range 50–100&nbsp;ppm boron equivalents) as a primary or adjunct pH buffer system in [[swimming pools]]. Boric acid is a weak acid, with p''K''{{sub|a}} (the pH at which buffering is strongest because the free acid and borate ion are in equal concentrations) of 9.24 in pure water at 25&nbsp;°C. But apparent p''K''{{sub|a}} is substantially lower in swimming pool or ocean waters because of interactions with various other molecules in solution. It will be around 9.0 in a salt-water pool. No matter which form of soluble boron is added, within the acceptable range of pH and boron concentration for swimming pools, boric acid is the predominant form in aqueous solution, as shown in the accompanying figure. The boric acid – borate system can be useful as a primary buffer system (substituting for the [[bicarbonate]] system with p''K''{{sub|a{{sub|1}}}} = 6.0 and p''K''{{sub|a{{sub|2}}}} = 9.4 under typical salt-water pool conditions) in pools with salt-water chlorine generators that tend to show upward drift in pH from a working range of pH 7.5–8.2. [[Buffer capacity]] is greater against rising pH (towards the pKa around 9.0), as illustrated in the accompanying graph. The use of boric acid in this concentration range does not allow any reduction in free [[Hypochlorous acid|HOCl]] concentration needed for pool sanitation, but it may add marginally to the photo-protective effects of [[cyanuric acid]] and confer other benefits through anti-corrosive activity or perceived water softness, depending on overall pool solute composition.<ref name=birch2013/>

===Lubrication===
Colloidal suspensions of nanoparticles of boric acid dissolved in petroleum or vegetable oil can form a remarkable lubricant on ceramic or metal surfaces<ref name=duzc2009/> with a coefficient of sliding friction that decreases with increasing pressure to a value ranging from 0.10 to 0.02. Self-lubricating {{chem2|B(OH)3}} films result from a spontaneous chemical reaction between water molecules and {{chem2|B2O3}} coatings in a humid environment. In bulk-scale, an inverse relationship exists between friction coefficient and Hertzian contact pressure induced by applied load.{{citation needed|date=June 2022}}

Boric acid is used to lubricate [[carrom]] and [[novuss]] boards, allowing for faster play.<ref name=singh2009/>

===Nuclear power===
Boric acid is used in some [[nuclear power plant]]s as a [[neutron poison]]. The boron in boric acid reduces the probability of [[nuclear fission|thermal fission]] by absorbing some [[thermal neutron]]s. [[Nuclear chain reaction|Fission chain reaction]]s are generally driven by the probability that free neutrons will result in fission and is determined by the material and geometric properties of the reactor. Natural boron consists of approximately 20% boron-10 and 80% boron-11 isotopes. Boron-10 has a high [[nuclear cross section|cross-section]] for absorption of low energy (thermal) neutrons. By increasing boric acid concentration in the reactor coolant, the probability that a neutron will cause fission is reduced. Changes in boric acid concentration can effectively regulate the rate of fission taking place in the reactor. During normal at power operation, boric acid is used only in [[pressurized water reactor]]s (PWRs), whereas [[boiling water reactor]]s (BWRs) employ [[control rod]] pattern and coolant flow for power control, although BWRs can use an aqueous solution of boric acid and [[borax]] or [[sodium pentaborate]] for an emergency shutdown system if the control rods fail to insert. Boric acid may be dissolved in [[spent fuel pool]]s used to store [[Spent nuclear fuel|spent fuel]] elements. The concentration is high enough to keep neutron multiplication at a minimum. Boric acid was dumped over Reactor 4 of the [[Chernobyl disaster|Chernobyl]] nuclear power plant after its [[nuclear meltdown|meltdown]] to prevent another reaction from occurring.{{citation needed|date=October 2013}}

===Pyrotechnics===
Boron is used in [[pyrotechnics]] to prevent the [[amide]]-forming reaction between [[aluminium]] and [[nitrate]]s. A small amount of boric acid is added to the composition to neutralize alkaline amides that can react with the aluminium.

Boric acid can be used as a colorant to make fire green. For example, when dissolved in [[methanol]] it is popularly used by [[torch (juggling)|fire jugglers]] and fire spinners to create a deep green flame much stronger than copper sulfate.<ref name=weing1947/>

===Agriculture===
Boric acid is used to treat or prevent [[Boron deficiency (plant disorder)|boron deficiencies]] in plants. It is also used in preservation of grains such as rice and wheat.<ref name=CFS2019/>

==References==
<references>
<ref name="webster">[https://www.merriam-webster.com/dictionary/boracic%20acid Entry "boracic acid"] in the online ''Merriamm-Webster Dictionary''. Gives the first use as 1790. Retrieved 2022-06-24.</ref>
<ref name="eisler2007">{{cite book|url=https://books.google.com/books?id=B3qXQswP8zIC|page=59|title=Eisler's Encyclopedia of Environmentally Hazardous Priority Chemicals|author=Ronald Eisler|year=2007|isbn=978-0-08-054707-7|publisher=Elsevier}}</ref>
<ref name="balci2012">{{Cite journal |last1=Balci |first1=Suna |last2=Sezgi |first2=Naime |last3=Eren |first3=Esin |title=Boron Oxide Production Kinetics Using Boric Acid as Raw Material |journal=Industrial & Engineering Chemistry Research |volume=51 |issue=34 |pages=11091–11096 |doi=10.1021/ie300685x |year=2012 }}</ref>
<ref name="jolly1984">{{cite book |last= Jolly |first=W. L. |title= Modern Inorganic Chemistry |publisher= McGraw-Hill |year= 1984 |page= 198 }}</ref>
<ref name="JEE2014">{{Cite book|url=https://books.google.com/books?id=BcF_AQAAQBAJ|title=Comprehensive Chemistry for JEE Advanced 2014|last=MHE|publisher=Tata McGraw-Hill Education|via=Google Books|page=15.5|isbn=978-1-259-06426-5}}</ref>
<ref name="darp2000">{{cite book|url=https://archive.org/details/bub_gb_N-gDAAAAMBAJ|title=Competition Science Vision|first=Pratiyogita|last=Darpan|date=1 May 2000|publisher=Pratiyogita Darpan|via=Internet Archive}}</ref>
<ref name="NIST1969">{{Cite book| publisher = U.S. Government Printing Office| title = NIST Special Publication| date = 1969}}</ref>
<ref name="rota2017">Andrei Rotaru (2017): "Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow." ''Journal of Thermal Analysis and Calorimetry'', volume 127, pages 755–763. {{doi|10.1007/s10973-016-5583-7}}</ref>
<ref name="brown1956">{{cite journal|last1=Brown|first1=Herbert C.|last2=Mead |first2=Edward J. |last3=Shoaf |first3=Charles J. |year=1956|title=Convenient procedures for the preparation of alkyl borate esters|journal=J. Am. Chem. Soc.|volume=78|issue=15|pages=3613–3614|doi=10.1021/ja01596a015}}</ref>
<ref name="ncbi">{{cite web | url=https://pubchem.ncbi.nlm.nih.gov/compound/7628#section=IUPAC-Name&fullscreen=true | title=Boric acid }}</ref>
<ref name="chemsrc">{{Cite web|url=https://www.chemsrc.com/en/cas/10043-35-3_670326.html|title=boric_msds}}</ref>
<ref name="hous2008">{{cite book |title= Inorganic Chemistry |edition= 3rd |chapter= Chapter 13: The Group 13 Elements |last1= Housecroft |first1=C. E. |last2= Sharpe |first2=A. G. |publisher= Pearson |year= 2008 |isbn= 978-0-13-175553-6 |page= 340 }}</ref>
<ref name="hous2005">{{cite book |last1= Housecroft |first1=C.E. |last2=Sharpe |first2=A.G. |title= Inorganic Chemistry |edition=2nd |publisher= Pearson Prentice-Hall |year= 2005 |pages= 314–5 }}</ref>
<ref name="tsuy2007">{{cite journal |last1= Tsuyumoto |first1=I. |last2=Oshio |first2=T. |last3=Katayama |first3=K. |title= Preparation of highly concentrated aqueous solution of sodium borate |year= 2007 |journal= Inorganic Chemistry Communications |volume= 10 |issue= 1 |pages= 20–22 |doi= 10.1016/j.inoche.2006.08.019 }}</ref>
<ref name="tsuy2009">{{cite journal |last1= Tsuyumoto |first1=I. |last2=Oshio |first2=T. |title= Development of fire resistant laminated wood using concentrated sodium polyborate aqueous solution |year= 2009 |journal= Journal of Wood Chemistry and Technology |volume= 29 |issue= 4 |pages= 277–285 |doi= 10.1080/02773810903033721 |s2cid=98730912 }}</ref>
<ref name="GandE">{{Greenwood&Earnshaw}}</ref>
<ref name="vogelP357">{{VogelQuantitative6th|page=357}}</ref>
<ref name="HHS2010">{{cite web |website=Centers for Disease Control |title= Toxicological Profile for Boron |page= 11 |date=November 2010  |url= http://www.atsdr.cdc.gov/toxprofiles/tp26.pdf }}</ref>
<ref name="FQPA2006">{{cite web |title=Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Eligibility Decision (TRED) for Boric Acid/Sodium Borate Salts |website=United States Environmental Protection Agency |url= http://www.epa.gov/oppsrrd1/REDs/boric_acid_tred.pdf |archive-url= https://web.archive.org/web/20061006094329/http://www.epa.gov/oppsrrd1/REDs/boric_acid_tred.pdf |archive-date=2006-10-06 |year=2006 |access-date=2008-04-21}}</ref>
<ref name="CLH2018">{{cite web |title= CLH report for boric acid – Proposal for Harmonised Classification and Labelling |publisher= Bureau for Chemical Substances |url= https://echa.europa.eu/documents/10162/23665416/clh_rep_boric_acid_5521_en.pdf/ee39f026-9d2d-28f7-5d90-63a424112162 |date= 23 April 2018 |access-date= 18 October 2018 |place= Lodz, Poland }}</ref>
<ref name="BYU2008">{{cite web |url=http://lifesciences.byu.edu/Portals/6/docs/BoricAcid.pdf |archive-url=https://web.archive.org/web/20111216012612/http://lifesciences.byu.edu/Portals/6/docs/BoricAcid.pdf |archive-date=16 December 2011 |title=Boric acid, ACC# 03260 MSDS |date=11 February 2008 |access-date=2009-09-24 }}</ref>
<ref name="ishii1993">{{cite journal |last1=Ishii |first1=Y. |last2=Fujizuka |first2=N. |last3=Takahashi |first3=T. |last4=Shimizu |first4=K. |last5=Tuchida |first5=A. |last6=Yano |first6=S. |last7=Naruse |first7=T. |last8=Chishiro |first8=T. |display-authors=3 |title=A fatal case of acute boric acid poisoning |journal=Clinical Toxicology |year=1993 |volume=31 |issue=2 |pages=345–352 |doi=10.3109/15563659309000402 |pmid=8492348}}</ref>
<ref name="rest1992">{{cite journal |last1=Restuccio |first1=A. |last2=Mortensen |first2=M. E. |last3=Kelley |first3=M. T. |title=Fatal ingestion of boric acid in an adult |journal=American Journal of Emergency Medicine |year=1992 |volume=10 |issue=6 |pages=545–547 |pmid=1388380 |doi=10.1016/0735-6757(92)90180-6}}</ref>
<ref name="duld2009">{{cite encyclopedia |url= https://www.nlm.nih.gov/medlineplus/ency/article/002485.htm |encyclopedia=A.D.A.M. Medical Encyclopedia |publisher=MedLine Plus |title=Boric acid poisoning |last=Duldner |first=J. E. |date=30 January 2009}}</ref>
<ref name="NSWFA2009">{{cite web |url= http://www.foodauthority.nsw.gov.au/consumers/other-food-topics/borax-and-boric-acid/ |title= Borax and boric acid |access-date= 2009-09-24 |author= NSW Food Authority |publisher= New South Wales Government |location= Australia |archive-date= 15 October 2009 |archive-url= https://web.archive.org/web/20091015061849/http://www.foodauthority.nsw.gov.au/consumers/other%2Dfood%2Dtopics/borax%2Dand%2Dboric%2Dacid/ }}</ref>
<ref name="ECHA2010">{{cite web |url=https://echa.europa.eu/documents/10162/13638/supdoc_boric_acid_20100609_en.pdf |title=Boric acid as a substance of very high concern because of its CMR properties |publisher=ECHA Document library |access-date=28 May 2017 |archive-date=18 May 2016 |archive-url=https://web.archive.org/web/20160518224000/http://echa.europa.eu/documents/10162/13638/supdoc_boric_acid_20100609_en.pdf }}</ref>
<ref name="EUP2008">[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:353:0001:1355:en:PDF Regulation (EC) No 1272/2008 of the European Parliament and of the Council, 16 December 2008]</ref>
<ref name="kist1994">{{cite book |last1= Kistler |first1=R. B. |last2=Helvaci |first2=C. |editor-last= Carr |editor-first= D. D. |chapter= Boron and Borates |title= Industrial Minerals and Rocks |edition= 6th |year= 1994 |publisher= SME |location= Littleton, CO |pages= 171–186 }}</ref>
<ref name="demp2010">{{cite web |first= Jock |last=Dempsey |title= Borax |url= http://www.anvilfire.com/21centbs/material/borax01.htm |publisher= Dempsey's Forge |orig-date= 1998 |year= 2009 |access-date= 2010-07-23 }}</ref>
<ref name="silly2013">{{cite web|first=Felice |last=Prager | url=http://www.loti.com/silly_putty.htm |title=Science Becomes a Toy – Silly Putty |publisher=Rewind the Fifites |work=Loti.com |access-date=2013-06-07 |archive-url=https://web.archive.org/web/20130512100402/http://www.loti.com/silly_putty.htm |archive-date=2013-05-12}}</ref>
<ref name="PDEP2010">{{cite web |url= http://files.dep.state.pa.us/OilGas/BOGM/BOGMPortalFiles/MarcellusShale/Frac%20list%206-30-2010.pdf |title= Chemicals used by hydraulic fracturing companies in pennsylvania for surface and hydraulic fracturing activities |publisher= Pennsylvania Department of Environmental Protection, Bureau of Oil and Gas Management |date= 30 June 2010}}</ref>
<ref name="fink2015">{{cite book|chapter=Fracturing fluids|year=2015|pages=567–651|doi=10.1016/B978-0-12-803734-8.00017-5|title=Petroleum Engineer's Guide to Oil Field Chemicals and Fluids|isbn=978-0-12-803734-8|last1=Fink|first1=Johannes}}</ref>
<ref name="bish2004">{{cite journal|last1=Bishop|first1=Maximilienne|last2=Shahid|first2=Naureen|last3=Yang|first3=Jianzhong|last4=Barron|first4=Andrew R.|title=Determination of the mode and efficacy of the cross-linking of guar by borate using MAS<sup>11</sup>B NMR of borate cross-linked guar in combination with solution<sup>11</sup>B NMR of model systems|journal=Dalton Trans.|issue=17|year=2004|pages=2621–2634|issn=1477-9226|doi=10.1039/B406952H|pmid=15514744}}</ref>
<ref name="EUP3004279">{{cite web|url=https://patents.google.com/patent/EP3004279A1/en|title=European Patent EP3004279A1. Concentrated borate crosslinking solutions for use in hydraulic fracturing operations|publisher=European Patent Office|access-date=27 October 2019}}</ref>
<ref name="wang2016">{{cite journal|last1=Wang|first1=Shibin|last2=Tang|first2=Hongbiao|last3=Guo|first3=Jianchun|last4=Wang|first4=Kunjie|title=Effect of pH on the rheological properties of borate crosslinked hydroxypropyl guar gum hydrogel and hydroxypropyl guar gum|journal=Carbohydrate Polymers|volume=147|year=2016|pages=455–463|issn=0144-8617|doi=10.1016/j.carbpol.2016.04.029|pmid=27178952}}</ref>
<ref name="aber2010">{{cite book |last=Abercrombie |first=P. |title=Integrative Women's Health |publisher=Oxford University Press |year=2010 |isbn=978-0-19-537881-8 |editor-last1=Maizes |editor-first1=V. |location=New York, NY |page=192 |chapter=Vaginitis |doi=10.1093/med/9780190214791.003.0013 |editor-last2=Low Dog |editor-first2=T.}}</ref>
<ref name="iava2010">{{cite journal |vauthors=Iavazzo C, Gkegkes ID, Zarkada IM, Falagas ME |title=Boric acid for recurrent vulvovaginal candidiasis: the clinical evidence |journal=J Womens Health (Larchmt) |volume=20 |issue=8 |pages=1245–55 |date=August 2011 |pmid=21774671 |doi=10.1089/jwh.2010.2708 }}</ref>
<ref name="sobel2021">{{cite journal | vauthors = Sobel JD, Sobel R | title = Current and emerging pharmacotherapy for recurrent bacterial vaginosis | journal = Expert Opin Pharmacother | volume = 22 | issue = 12 | pages = 1593–1600 | date = August 2021 | pmid = 33750246 | doi = 10.1080/14656566.2021.1904890 | s2cid = 232325625}}</ref>
<ref name="adisTOL463">{{cite web | url=https://adisinsight.springer.com/drugs/800047491 | title=TOL 463 – AdisInsight}}</ref>
<ref name="nyir2022">{{cite journal | vauthors = Nyirjesy P, Brookhart C, Lazenby G, Schwebke J, Sobel JD | title = Vulvovaginal Candidiasis: A Review of the Evidence for the 2021 Centers for Disease Control and Prevention of Sexually Transmitted Infections Treatment Guidelines | journal = Clin Infect Dis | volume = 74 | issue = Suppl_2 | pages = S162–S168 | date = April 2022 | pmid = 35416967 | doi = 10.1093/cid/ciab1057 }}</ref>
<ref name="marra2019">{{cite journal | vauthors = Marrazzo JM, Dombrowski JC, Wierzbicki MR, Perlowski C, Pontius A, Dithmer D, Schwebke J | title = Safety and Efficacy of a Novel Vaginal Anti-infective, TOL-463, in the Treatment of Bacterial Vaginosis and Vulvovaginal Candidiasis: A Randomized, Single-blind, Phase 2, Controlled Trial | journal = Clin Infect Dis | volume = 68 | issue = 5 | pages = 803–809 | date = February 2019 | pmid = 30184181 | pmc = 6376090 | doi = 10.1093/cid/ciy554}}</ref>
<ref name="adriz2018">{{cite journal |journal= Korean J Fam Med |date= January 2018 |volume= 39 |issue= 1 |pages= 2–9 |doi= 10.4082/kjfm.2018.39.1.2 |pmc= 5788841 |pmid= 29383205 |title= Efficacy of Boric Acid as a Treatment of Choice for Chronic Suppurative Otitis Media and Its Ototoxicity |first1= I. |last1= Adriztina |first2= L. I. |last2= Adenin |first3= Y. M. |last3= Lubis}}</ref>
<ref name="harv1980">{{cite book |last= Harvey |first= S. C. |editor1-last= Gilman |editor1-first= A. G. |editor1-link= Alfred G. Gilman |editor2-last= Goodman |editor2-first= L. S. |editor2-link= Louis S. Goodman |editor3-last= Gilman |editor3-first= A. |editor3-link= Alfred Gilman, Sr. |chapter= Antiseptics and Disinfectants; Fungicides; Ectoparasiticides |title= Goodman & Gillman's The Pharmacological Basis of Therapeutics |year= 1980 |edition= 6th |page= [https://archive.org/details/goodmangilmansphe6good/page/971 971] |isbn= 978-0-02-344720-4 |title-link= Goodman & Gillman's The Pharmacological Basis of Therapeutics |publisher= Macmillan }}</ref>
<ref name="EPA2015">{{cite web |url= https://www.epa.gov/sites/default/files/2015-12/documents/3052.pdf |title= Method 3052 microwave assisted acid digestion of siliceous and organically based matrices |publisher= US EPA |date= 2015-06-22 }}</ref>
<ref name="ABC">{{Cite web | url=http://www.americanborate.com/all-about-borates/borate-applications/borates-in-pesticides/ | title=Borates in Pesticides &#124; AMERICAN BORATE COMPANY}}</ref>
<ref name="boone">{{Cite web |date=2012|author1=Boone, C. |author2=Bond, C. |author3=Stone, D. |title=Boric Acid General Fact Sheet|publisher=[[National Pesticide Information Center]], Oregon State University Extension Services|url=http://npic.orst.edu/factsheets/boricgen.html}}</ref>
<ref name="REDF2022">{{cite web |url=https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-011001_1-Sep-93.pdf |title=R.E.D. Facts – Boric Acid |publisher=United States Environmental Protection Agency |access-date=2 April 2022 |archive-url=https://web.archive.org/web/20211223131332/https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-011001_1-Sep-93.pdf |archive-date=23 December 2021 |url-status=live}}</ref>
<ref name="birch2013">{{cite web |last= Birch |first= Robert G |title= Boric acid as a swimming pool buffer |publisher= The University of Queensland |date= 2013 |url= https://scithings.id.au/Boric_acid.pdf |access-date= 30 November 2013 }}</ref>
<ref name="duzc2009">{{cite journal |last1= Düzcükoğlu |first1=H. |last2=Acaroğlu |first2=M. |title= Lubrication Properties of Vegetable Oils Combined with Boric Acid and Determination of Their Effects on Wear |journal= Energy Sources, Part A: Recovery, Utilization, and Environmental Effects |volume= 32 |issue= 3 |year= 2009 |pages= 275–285 |doi= 10.1080/15567030802606053 |s2cid=97537085 }}</ref>
<ref name="singh2009">{{cite web |url= http://pscamohali.googlepages.com/standardequipments |title= Standard equipments |publisher= Punjab State Carrom Association |access-date= 2009-09-24 |first= Harpreet |last= Singh |archive-date= 14 March 2007 |archive-url= https://web.archive.org/web/20070314085602/http://pscamohali.googlepages.com/standardequipments |url-status= dead }}</ref>
<ref name="weing1947">{{Cite book|title=Pyrotechnics|last=Weingart|first=George|publisher=Chemical Publishing Company|year=1947|isbn=978-0-8206-0112-0}}</ref>
<ref name="CFS2019">{{Cite web|url=https://www.cfs.gov.hk/english/programme/programme_rafs/programme_rafs_fa_02_06.html|title=Use of Boric Acid and Borax in Food|website=cfs.gov.hk|access-date=2019-05-22}}</ref>
<ref name="kaur2021">Gurwinder Kaur, Shagun Kainth, Rohit Kumar, Piyush Sharma and O. P. Pandey (2021): "Reaction kinetics during non-isothermal solid-state synthesis of boron trioxide via boric acid dehydration." ''Reaction Kinetics, Mechanisms and Catalysis'', volume 134, pages 347–359. {{doi|10.1007/s11144-021-02084-8}}</ref>
<ref name="aghi2018">Siavash Aghili, Masoud Panjepour, and Mahmood Meratian (2018): "Kinetic analysis of formation of boron trioxide from thermal decomposition of boric acid under non-isothermal conditions." ''Journal of Thermal Analysis and Calorimetry'', volume 131, pages 2443–2455. {{doi|10.1007/s10973-017-6740-3}}</ref>
<ref name="tachi2004">Masanori Tachikawa (2004): "A density functional study on hydrated clusters of orthoboric acid, B(OH)<sub>3</sub>(H<sub>2</sub>O)<sub>''n''</sub> (''n''=1–5)". ''Journal of Molecular Structure: THEOCHEM'', volume 710, issues 1–3, pages 139-150. {{doi|10.1016/j.theochem.2004.09.008}}</ref>
</references>

==Further reading==
* {{cite book | author = Jolly, W. L. | title = Modern Inorganic Chemistry | edition = 2nd | location = New York | publisher = McGraw-Hill | year = 1991 | isbn = 978-0-07-112651-9 }}
* {{cite book |author1=Goodman, L. |author2=Gilman, A. |author3=Brunton, L. |author4=Lazo, J. |author5=Parker, K. | location = New York | publisher = McGraw Hill | year = 2006 | title = Goodman & Gilman's The Pharmacological Basis of Therapeutics }}
* Cordia JA, Bal EA, Mak WA and Wils ERJ (2003), ''Determination of some physico-chemical properties of Optibor'' EP. Rijswijk, The Netherlands: TNO Prins Maurits Laboratory, report PML 2002-C42rr, GLP, Unpublished, confidential data provided by Bor ax Europe Limited

==External links==
* {{commons category-inline|Boric acid}}
* [http://npic.orst.edu/factsheets/archive/borictech.pdf Boric Acid Technical Fact Sheet – National Pesticide Information Center]
* [http://npic.orst.edu/factsheets/boricgen.pdf Boric Acid General Fact Sheet – National Pesticide Information Center]
* [http://www.inchem.org/documents/icsc/icsc/eics0991.htm International Chemical Safety Card 0991]
* [https://web.archive.org/web/20080406065032/http://www.epa.gov/oppsrrd1/REDs/factsheets/0024fact.pdf US EPA Pesticide Reregistration Eligibility Decision]
* [https://web.archive.org/web/20060209040519/http://www.npi.gov.au/database/substance-info/profiles/15.html National Pollutant Inventory – Boron and compounds]
* [https://web.archive.org/web/20021212234630/http://www.chemicalland21.com/arokorhi/industrialchem/inorganic/BORIC%20ACID.htm Boric acid at ChemicalLand21]
* [https://web.archive.org/web/20100401084438/http://echa.europa.eu/doc/press/pr_10_03_svhc_consultation_20100308.pdf European Chemicals Agency (ECHA)"New Public Consultation on Eight Potential Substances of Very High Concern" – includes Boric Acid. Closes 22 April 2010]
* [http://chemsub.online.fr/name/Boric_acid.html ChemSub Online: Boric acid]

{{Boron compounds}}
{{Hydrogen compounds}}
{{Otologicals}}
{{Insecticides}}

{{Authority control}}

[[Category:Antifungals]]
[[Category:Antifungals for dermatologic use]]
[[Category:Antiseptics]]
[[Category:Ants]]
[[Category:Borates]]
[[Category:E-number additives]]
[[Category:Inorganic compounds]]
[[Category:Inorganic insecticides]]
[[Category:Insecticides]]
[[Category:Mineral acids]]
[[Category:Neutron poisons]]
[[Category:Otologicals]]
[[Category:Photographic chemicals]]
[[Category:Preservatives]]
[[Category:Pyrotechnic chemicals]]
[[Category:Rheology]]
[[Category:Testicular toxicants]]