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Acide Borique ( Boric Acid )

Acide borique
L'acide borique , aussi appelé acide boracique ou acide orthoborique, est un corps minéral composé de formule brute H3BO3 ou structurelle B(OH)3, nommé autrefois sassoline
 en Italie centrale, où il jaillit à l'état naturel dans les fumerolles brûlantes et se dépose avec les autres vapeurs condensées dans les lagoni de Toscane6. Ce solide blanc, 
parfois légèrement coloré, cristallise dans un réseau triclinique. Il se présente sous forme d'un solide cristallisé en paillettes nacrées.

Assez peu soluble dans l'eau, c'est un acide faible à très faible. Il est souvent employé comme antiseptique bien que toxique, insecticide, absorbeur de neutrons dans les
 centrales nucléaires pour contrôler le taux de fission de l'uranium, et comme précurseur d'autres composés chimiques. Cet acide de Lewis tire son nom de l'un de ses composants, 
le bore, sa formule brute est H3BO3 ou en respectant mieux la structure à liaisons covalentes B(OH)3.

L'acide borique moléculaire peut provenir de la simple décomposition du minéral naturel nommée sassolite qui, décrit par sa formule B(OH)3, n'est qu'un assemblage de plans d'acide
 borique stabilisés par des liaisons hydrogènes7. Il existe sous forme de cristaux incolores ou de poudre blanche se dissolvant dans l'eau.


abrication
L'acide borique est produit principalement à partir de minerai de borate par sa réaction avec l’acide sulfurique. La plus grande source de borates dans le monde est une mine à ciel ouvert située à Boron (en).

L'acide borique a été produit pour la première fois par Wilhelm Homberg (1652-1715) à partir du borax, sous l'action d’acides minéraux, et a reçu le nom de « sal sedativum Hombergi ».

Dans la nature
L'acide libre est présent sous forme native ou régénérée dans certaines zones possédant des batholithes granitiques proches de la surface telles que la Toscane, les îles Lipari et au Nevada, ses effluents sont mélangés à la vapeur issue des fissures de la croûte terrestre. En Toscane, on récupère l'acide borique dans des jets de vapeur d'eau surchauffée (100 à 215 °C) d'origine volcanique, exploités comme source d'énergie ; la vapeur, hydrolysant des borates dans les profondeurs du sol de cette région, contient en effet de l'acide borique et divers sels minéraux. Celle qui s'échappe librement des fissures du sol (soffioni) est simplement condensée dans des bassins (lagoni).

La présence de l'acide borique ou de ses sels a été décelée dans l’eau de mer, et existerait également dans les végétaux et plus particulièrement dans presque tous les fruits8 où il pourrait jouer un certain rôle d'insecticide naturel.


Disposition spatiale de molécules (hélicoïdales) d'acide borique dans son cristal artificiel ou dans la sassolite naturelle.
L'acide borique est le produit de dégradation ultime (souvent à l'aide d'un acide fort) de nombreux borates : borax, boracite, boronatrocalcite, colemanite, borocalcite, ascharite, kaliborite, kernite, kurnakovite, pinnaïte, pandermite, tunellite, larderellite, probertite, inderite, hydroboracite, etc., mais aussi howlite et bakérite, en plus des minéraux qui peuvent contenir l'acide borique en partie comme la harkérite ou la sassolite.

Propriétés
Dilué dans l'eau, l'acide borique, acide très faible, se nomme l'eau borée.

Solubilité
L'acide borique est assez faiblement soluble dans l'eau froide.

Tableau de solubilité9
Masse dissoute (g)
pour 100 g d'eau Température
2,66 0 °C
3,57 10 °C
5,04 20 °C
6,6 30 °C
8,72 40 °C
11,54 50 °C
14,81 60 °C
16,73 70 °C
23,75 80 °C
30,38 90 °C
40,25 100 °C
L'acide borique est beaucoup plus soluble dans l’eau chaude et surtout dans l'eau bouillante. Dans l'eau à température ordinaire il se dissout à la condition d'être finement divisé 
jusqu'à une teneur en bore proche de 4 000 ppm où un début de cristallisation est observé.

L'acide borique est soluble dans le glycérol (glycérine), soit 22,2 g pour 100 g de solvant à 20 °C et 28 g à 25 °C. Il est soluble aussi dans le méthanol, soit 20,2 g pour 100 g à 
25 °C. Il l'est nettement moins dans l'éthanol (5,5 g pour 100 g à 25 °C), dans l'éther éthylique (0,24 g pour 100 g à 25 °C). Il est insoluble dans l'acétone.

Chimie
L'acide (ortho)borique est fabriqué à partir de (méta)borates en chaîne ou cyclique, en particulier de borax. Ce sont en fait des réactions de dégradation avec l'acide chlorhydrique 
et l'acide sulfurique qui génèrent l'acide borique.

L'acide borique est aussi le produit de l'hydratation du sesquioxyde de bore, acide monobasique faible soit :

B2O3 solide en poudre + 3 H2O → 2 B(OH)3 aq
Propriété acide-base
L'acide borique est un acide de Lewis, il accepte les électrons des ions hydroxyles10, en conséquence il capte ces derniers en formant des structures ioniques : tétraèdre, structure
 géométrique pentacoordinée ou bipyramide, structure hexacoordinée, etc.

Ainsi l'acide borique ne se dissocie pas en solution aqueuse, mais son activité acide est due à son interaction avec les molécules d’eau :

B(OH)3 + H2O → B(OH)4−+ H+
Ka = 5,8 × 10−10 mol/L ; pKa = 9,14.
Des anions polyborates se forment lentement à pH 7,10 si la concentration en bore est au-dessus de 0,025 mol/L. Le plus connu de ces derniers est l'ion tétraborate, à structure cyclique, 
trouvé dans le borax minéral :

4B(OH)4− + 2H+ → B4O72− + 9H2O
En résumé, l'acide borique est essentiellement un acide faible monobasique. Il est possible d'écrire, avec la convention gommant une molécule d'eau H20 soit H2BO3– aqueux pour l'ion 
tétrahydroxyborate B(OH)4−, les équilibres acido-basiques :

H3BO3 aqueux → H+aqueux + H2BO3–aqueux
H2BO3–aqueux → H2O + BO2–aqueux
L'acide borique peut être dosé en étalon par une solution de soude, suivant la réaction faisant le métaborate de sodium, sel de sodium de l'acide métaborique :

H3BO3 aqueux + NaOHaqueux → NaBO2 aqueux + 2 H2O
Ce dosage peut être amélioré en ajoutant à la solution d'acide borique des composés organiques polyhydroxylés, du type glycérol, mannitol, sucres divers, etc., qui augmentent 
la force de l'acide borique et permettent en pratique de mieux connaître avec précision 
la fin du dosage.

Chimie à la température d'ébullition de l'eau et au-delà
Portée et maintenue à ébullition à 100 °C, la solution aqueuse d'acide borique donne un dépôt d'acide métaborique, ici écrit avec une formule équivalente simplifiée11 :

B(OH)3 aq à ébullition → HBO2 + H2Ogaz
Par chauffage au rouge, l'acide métaborique se transforme en sesquioxyde de bore, en perdant l'équivalent d'une molécule d'eau.

2 HBO2 solide chauffé au rouge → B2O3 solide + H2Ogaz
Les sels de l'acide borique sont complexes.

Du fait d'une transformation de structure par une transition progressive initié entre 169 °C et 171 °C et généralement terminée vers 185 °C, l'acide borique solide sec se déshydrate, 
formant l’acide métaborique HBO2. L'acide métaborique est un cristal cubique, blanc et légèrement soluble dans l'eau. Il fond à environ 236 °C et une fois chauffé au-dessus de 300 °C, il se déshydrate en formant l'acide tétraborique ou l’acide pyroborique, H2B4O7. Le terme d’acide borique peut se rapporter à l’un ou l’autre de ces composés. À une température légèrement plus élevée, il se forme du sesquioxyde de bore.

Toxicité, écotoxicité
Autrefois souvent présenté comme guère plus toxique que le sel de table (sur la base de la dose létale 50 estimée à 2 660 mg·kg-1 de masse corporelle) pour l'homme, il a une activité 
fongicide et insecticide qui laisse penser qu'il ne serait pas neutre pour l'environnement en cas de pollution importante.
Toxique pour l'homme (selon l'INRS par exemple) par voie digestive ou par inhalation. L'ANSM et les centres de pharmacovigilance ont mis en garde sur le caractère reprotoxique ainsi que
 sur la toxicité aiguë12. Certains groupes ethniques l'utilisent comme additif alimentaire pour l'homme ou l'animal domestique, mais au Canada, l'ACIA demande aux éleveurs et 
restaurateurs de ne pas l'utiliser en raison d'un « risque inacceptable pour la santé du consommateur » (à cause de mortalités d'adultes ou bébés)13. En France dans les officines 
l'utilisation d'acide borique nécessite de travailler sous une hotte avec gants, lunettes et masque.
À forte concentration, il est irritant pour les yeux, la peau et les voies respiratoires - en cas d'exposition, même courte - et il peut avoir des effets sur les reins en cas
 d'exposition prolongée ou d'expositions répétées.
On connaît mal sa toxicité environnementale, sauf pour les insectes contre lesquels il est utilisé comme insecticide autorisé pour certains usages dans certains pays. Les insectes
 se contaminent en se nettoyant après un contact avec ce produit. Il agit sur leur estomac, conduisant à la mort de l'insecte en une dizaine de jours. Son efficacité persiste plusieurs 
années dans les endroits secs.

Il est classé reprotoxique 2 (CMR) par la Communauté européenne. Son emploi est désormais règlementé.
Utilisations
En agriculture
L'acide borique et ses sels sont utilisés comme fertilisants en agriculture conventionnelle et biologique14. La carence en bore est la carence en oligoéléments la plus répandue dans 
le monde et occasionne des pertes de rendement importantes chez les plantes cultivées et les arbres fruitiers15.

En médecine et biologie
Antiseptique
Il peut être utilisé comme antiseptique pour les brûlures ou les coupures et est parfois employé dans les pommades et les onguents ou est utilisé dans une solution très diluée comme 
bain oculaire (eau boriquée). Comme composé anti-bactérien, l'acide borique peut également être prescrit comme traitement de l’acné. On l'utilise encore comme antiseptique pour l'oreille 
en plongée scaphandre, à raison d'une goutte d'alcool boriqué à 2 % par oreille.[réf. nécessaire] Le borate de sodium, un antiseptique doux, associé à d’autres composants appropriés peut
 également être proposé en usage externe pour des maladies des yeux, telle que la sécheresse oculaire.

Antimycosique
L'acide borique peut être utilisé pour traiter les levures et les mycoses comme les candidoses (mycoses vaginales) en remplissant de poudre d'acide borique des ovules qui seront insérés 
dans la cavité vaginale au coucher pendant trois à quatre nuits consécutives. En solution il peut être prescrit pour traiter certaines formes d’otites externes (infection de l'oreille) 
chez l’homme ou l’animal. Le conservateur dans les flacons d'urine (bouchon rouge) au Royaume-Uni est de l’acide borique.

Il est également employé en prévention du pied d'athlète, en insérant la poudre dans les chaussettes ou les bas.

Solution tampon
Le borate de lithium est le sel de lithium de l'acide borique employé en laboratoire comme solution tampon pour le gel couramment employé dans les tampons d'électrophorèse des acides
 nucléiques (tels que les tampons TBE, SB et LB). Il peut être utilisé pour l’électrophorèse de l'ADN et de l'ARN, en gel de polyacrylamide et en gel d'agarose.

Insecticide
L'acide borique est également souvent utilisé comme insecticide relativement peu toxique, pour l’extermination des cancrelats, termites, fourmis, puces, et beaucoup d'autres insectes. 
Il peut être employé directement sous la forme de poudre pour les puces et les cancrelats, ou être mélangé avec du sucre ou de la gelée pour les fourmis. C'est également un composant 
de beaucoup d’insecticides du commerce. Dans cette utilisation, particulièrement dans le cas des cancrelats, l'acide borique sous forme de poudre est appliqué dans les zones fréquentées
 par les insectes. Les fines particules s'accrochent aux pattes des insectes et causent par la suite des brûlures chimiques mortelles. L'acide borique est commercialisé pour cet usage 
dans des quartiers résidentiels dans des zones urbaines infestées par les cancrelats.


Autres
Les borates et l'acide borique ont été employés :

depuis la période de la Grèce antique pour le nettoyage, la conservation des aliments et d'autres activités ;
dans l'industrie du bijou et de la soudure traditionnelle (plomberie), l'acide borique a été ou est encore employé en combinaison avec l'alcool dénaturé pour réduire l’oxydation de
surface et l’importance de l’oxydation sur les métaux pendant les opérations de métallurgie et de soudure ;
le mastic au silicone a été fabriqué à l'origine en ajoutant de l'acide borique à de l’huile de silicone. Maintenant le mastic commercialisé sous différents noms de marque contient
 également des quantités significatives de l’élément silicium (le silicium lié au silicone permet d’augmenter de 20 % l’élasticité du produit) ;
l'acide borique est couramment utilisé par les pyrotechniciens amateurs - en solution dans l’alcool - pour donner à la flamme une couleur vert clair, et pour empêcher la formation
 d’amide pendant la réaction entre l'aluminium et les nitrates : un peu d'acide borique est ajouté à la composition pour neutraliser les amides alcalines qui peuvent réagir avec
 l’aluminium ;
il est également employé en Inde et à travers le monde pour abattre la poussière sur les terrains de sport[Comment ?], pour diminuer le frottement et pour augmenter la vitesse du
 jeu au billard indien ;
comme biocide pour le traitement des eaux de piscines où il fait partie de la composition de la grande majorité des galets de chlore.
Règlementation
Depuis 2010, sa commercialisation et son emploi sont réglementés en Europe, en faveur de produits alternatifs, en raison de sa classification CMR - reprotoxique, et de son intégration
 dans le règlement REACH.

Acide borique
Boric-acid-2D.pngBoric-acid-3D-vdW.png
Représentations de la molécule d'acide borique
Identification
Nom UICPA acide borique
borate d'hydrogène
Synonymes
acide boracique
acide orthoborique

No CAS 10043-35-3
No ECHA 100.030.114
No CE 233-139-2
Code ATC S02AA03 D08AD
PubChem 7628
ChEBI 33118
No E E284
SMILES
[Afficher]
InChI
[Afficher]
Apparence cristaux incolores ou poudre blanche sans odeur1
Propriétés chimiques
Formule brute H3BO3  [Isomères]
Masse molaire2 61,833 ± 0,008 g/mol
H 4,89 %, B 17,48 %, O 77,63 %,
pKa 9,28 à 24,85 °C pour B(OH)3 / B(OH)4-, puis 10,7 et 13,8 pour les deux derniers couples acide-base
Propriétés physiques
T° fusion transformation par transition d'ordre 2 entre 169 °C et 171 °C en acide métaborique HBO2, décomposition à 185 °C, formation de B2O3 à 300 °C
Solubilité 47,2 g·l-1 (eau, 20 °C)3
Masse volumique 1,435 g·cm-3 à 15 °C4
Pression de vapeur saturante 2,7 mbar à 20 °C3
Thermochimie
S0gaz, 1 bar 295,23 J mol−1 K
S0solide 88,7 J mol−1 K
ΔfH0gaz -992,28 kJ mol−1
ΔfH0solide -1 093,99 kJ mol−1
Cristallographie
Système cristallin triclinique
Propriétés optiques
Indice de réfraction cristaux polyaxes, soit 1,337, 1,461 et 1,462

Principaux synonymes
Noms français :

ACIDE BORACIQUE
Acide borique
ACIDE ORTHOBORIQUE
BORON TRIHYDROXIDE
O-BORIC ACID
TRIHYDROXYDE DE BORE
Noms anglais :

BORA
BORACIC ACID
Borate compounds, Inorganic [10043-35-3], boric acid
Boric acid
HYDROGEN BORATE
ORTHOBORIC ACID
Utilisation et sources d'émission
Agent ignifuge, fabrication de produits pharmaceutiques
 
 
SYNONYMS Boracic Acid, Hydrogen Borate, Orthoboric Acid;
Boracic acid; Hydrogen orthoborate; Trihydroxyborane CAS NO. 10043-35-3; Boracic Acid, Hydrogen Borate, Orthoboric Acid; Boracic acid; Hydrogen orthoborate; Trihydroxyborane; Borsäure; ácido bórico; Acide borique; Orthoboric acid; TRIS-BORAT-EDTA PUFFER; TRIS-BORATE-EDTA; TRIS-BORATE-EDTA BUFFER; TRIS-BORATE-EDTA DISODIUM; Ant flip; basilitb; boric; Boric acid (BH3O3); Boric acid (H3BO3); boricacid(h3bo3); Boricacid,medicinal; Borofax; Boron hydroxide; Borsaure
CAS NO:10043-35-3, 11113-50-1 (Base); 13813-79-1 (orthoboric acid); 13460-50-9, 13780-71-7 (metaboric acid);                                                                                                                                   Boric acid, also called hydrogen borate, boracic acid, and orthoboric acid is a weak, monobasic Lewis acid of boron. However, some of its behaviour towards some chemical reactions suggest it to be tribasic acid in the Brønsted sense as well. Boric acid is often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other chemical compounds. It has the chemical formula H3BO3 (sometimes written B(OH)3), and exists in the form of colorless crystals or a white powder that dissolves in water. When occurring as a mineral, it is called sassolite.Occurrence
Boric acid, or sassolite, is found mainly in its free state in some volcanic districts, for example, in the Italian region of Tuscany, the Lipari Islands and the US state of Nevada. In these volcanic settings it issues, mixed with steam, from fissures in the ground. It is also found as a constituent of many naturally occurring minerals – borax, boracite, ulexite (boronatrocalcite) and colemanite. Boric acid and its salts are found in seawater. It is also found in plants, including almost all fruits.

Boric acid was first prepared by Wilhelm Homberg (1652–1715) from borax, by the action of mineral acids, and was given the name sal sedativum Hombergi ("sedative salt of Homberg"). However borates, including boric acid, have been used since the time of the ancient Greeks for cleaning, preserving food, and other activities.reparation
Boric acid may be prepared by reacting borax (sodium tetraborate decahydrate) with a mineral acid, such as hydrochloric acid:

Na2B4O7·10H2O + 2 HCl → 4 B(OH)3 [or H3BO3] + 2 NaCl + 5 H2O
It is also formed as a by product of hydrolysis of boron trihalides and diborane:[4]

B2H6 + 6 H2O → 2 B(OH)3 + 6 H2
BX3 + 3 H2O → B(OH)3 + 3 HX (X = Cl, Br, I)
Properties
Boric acid is soluble in boiling water. When heated above 170 °C, it dehydrates, forming metaboric acid (HBO2):

H3BO3 → HBO2 + H2O
Metaboric acid is a white, cubic crystalline solid and is only slightly soluble in water. Metaboric acid melts at about 236 °C, and when heated above about 300 °C further dehydrates, forming tetraboric acid, also called pyroboric acid (H2B4O7):

4 HBO2 → H2B4O7 + H2O
The term boric acid may sometimes refer to any of these compounds. Further heating (to about 330 °C)[5] leads to boron trioxide.

H2B4O7 → 2 B2O3 + H
2O
There are conflicting interpretations for the origin of the acidity of aqueous boric acid solutions. Raman spectroscopy of strongly alkaline solutions has shown the presence of B(OH)−
4 ion,[6] leading some to conclude that the acidity is exclusively due to the abstraction of OH− from water:

B(OH)3 + H2O ⇌ B(OH)−4 +  H+ (K = 7.3×10−10; pK = 9.14) or more properly expressed in the aqueous solution:

B(OH)3 + 2 H2O ⇌ B(OH)−4 + H3O+
This may be characterized[7][8][9] as Lewis acidity of boron toward OH−, rather than as Brønsted acidity.

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

4 [B(OH)4]− + 2  H+ ⇌ [B4O5(OH)4]2− + 7 H2O
Boric acid makes an important contribution to the absorption of low frequency sound in seawater.

Reactions
With polyols containing cis-vicinal diols, such as glycerol and mannitol, the acidity of the boric acid solution is increased. With different mannitol concentrations, the pK of B(OH)3 extends on five orders of magnitude (from 9 to 4): this exacerbed acidity of boric acid in the presence of mannitol is also sometimes referred as "mannitoboric acid".[11] Greenwood and Earnshawn (1997)[12] refer to a pK value of 5.15 while a pK value of 3.80 is also reported in Vogel's book. This is due to the formation of a boron-mannitol chelate, [B(C6H8O2(OH)4)2]−, also known as mannitoborate complex, according to the following complexation reaction releasing a proton:

(mannitoboric acid)
boric acid
B(OH)3 + 2 mannitolC6H14O6
 ⇌ 
mannitoborate complex
[B(C6H8O2(OH)4)2]− + 3 H2O + H+
(pKa ranging from 4 to 9, depending on the mannitol concentration)
This feature is used in analytical chemistry to determine the boron content in aqueous solution by potentiometric titration with a strong base, such as NaOH.[12]

Boric acid also dissolves in anhydrous sulfuric acid:

B(OH)3 + 6 H2SO4 → B(HSO4)4− + 2 HSO4− + 3 H3O+
Boric acid reacts with alcohols to form borate esters, B(OR)3 where R is alkyl or aryl. A dehydrating agent, such as concentrated sulfuric acid is typically added:

B(OH)3 + 3 ROH → B(OR)3 + 3 H2O
A variety of salts are also known, involving the planar trigonal BO33– borate anion.

Molecular and crystal structure
The three oxygen atoms form a trigonal planar geometry around the boron. The B-O bond length is 136 pm and the O-H is 97 pm. The molecular point group is C3h.

Crystalline boric acid consists of layers of B(OH)3 molecules held together by hydrogen bonds of length 272 pm. The distance between two adjacent layers is 318 pm.Toxicology
Based on mammalian median lethal dose (LD50) rating of 2,660 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 LD50 of boric acid is 5.14 g/kg for oral dosages given to rats, and that 5 to 20 g/kg has produced death in adult humans. For comparison's sake, the LD50 of salt is reported to be 3.75 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 g in infants, 5–6 g in children, and 15–20 g in adults. [...] However, a review of 784 human poisonings with boric acid (10–88 g) reported no fatalities, with 88% of cases being asymptomatic."[15]

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 mg/kg bw/day for 90 days. This level is far lower than the LD50.

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.
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 December 2010 is H360FD (May damage fertility. May damage the unborn child.)

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.

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

Boric acid is used in the production of the glass in LCD flat panel displays.

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

Boric acid, mixed with borax (sodium tetraborate decahydrate) at the weight ratio of 4:5, is highly soluble in water, though they are not so soluble separately.[26] The solution is used for fire retarding agent of wood by impregnation.

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

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 F− anions into complex salts. This process defeats the extreme toxicity of hydrofluoric acid, particularly its ability to sequester ionic calcium from blood serum which can lead to cardiac arrest and bone decomposition; such an event can occur from just minor skin contact with HF.

Boric acid is added to borax for use as welding flux by blacksmiths.

Boric acid, in combination with polyvinyl alcohol (PVA) or silicone oil, is used to manufacture Silly Putty.

Boric acid is also present in the list of chemical additives used for hydraulic fracturing (fracking) in the Marcellus Shale in Pennsylvania.[31] Indeed, it is often used in conjonction with guar gum as cross-linking and gelling agent for controlling the viscosity and the rheology of the fracking fluid injected at high pressure in the well. Indeed, it is important to control the fluid viscosity for keeping in suspension on long transport distances the grains of the propping agents aimed at maintaining the cracks in the shales sufficiently open to facilitate the gas extraction after the hydraulic pressure is relieved.[32][33][34] The rheological properties of borate cross-linked guar gum hydrogel mainly depend on the pH value.

Medical
Boric acid can be used as an antiseptic for minor burns or cuts and is sometimes used in salves and dressings, such as boracic lint. Boric acid is applied in a very dilute solution as an eye wash. Dilute boric acid can be used as a vaginal douche to treat bacterial vaginosis due to excessive alkalinity,as well as candidiasis due to non-albicans candida.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 otitis externa (ear infection) in both humans and animals. The preservative in urine sample bottles in the UK is boric acid.

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.

Insecticidal
Boric acid was first registered in the US as an insecticide in 1948 for control of cockroaches, termites, fire ants, fleas, silverfish, and many other insects. 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' exoskeletons. 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 cannibalistic, eat others killed by contact or consumption of boric acid, consuming the powder trapped in the dead roach and killing them, too.

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.

Boric acid is added to salt in the curing of cattle hides, calfskins, and sheepskins. This helps to control bacterial development, and helps to control insects.

pH buffer
Distribution between boric acid and borate ion versus pH assuming pKa = 9.0 (e.g. salt-water swimming pool)
Boric acid predominates in solution below pH 9
Buffer capacity of the boric acid - borate system versus pH assuming pKa = 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 ppm boron equivalents) as a primary or adjunct pH buffer system in swimming pools. Boric acid is a weak acid, with pKa (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 °C. But apparent pKa 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 pKa1 = 6.0 and pKa2 = 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 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.

Lubrication
Colloidal suspensions of nanoparticles 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 0.10 to 0.02. Self-lubricating H3BO3 films result from a spontaneous chemical reaction between water molecules and B2O3 coatings in a humid environment. In bulk-scale, an inverse relationship exists between friction coefficient and Hertzian contact pressure induced by applied load.

Boric acid is used to lubricate carrom and novuss boards, allowing for faster play.

Nuclear power
Boric acid is used in some nuclear power plants as a neutron poison. The boron in boric acid reduces the probability of thermal fission by absorbing some thermal neutrons. Fission chain reactions 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 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. Boric acid is used only in pressurized water reactors (PWRs) whereas boiling water reactors (BWRs) employ control rod pattern and coolant flow for power control. BWRs use an aqueous solution of boric acid and borax or sodium pentaborate for an emergency shut down system. Boric acid may be dissolved in spent fuel pools used to store 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 nuclear power plant after its meltdown to prevent another reaction from occurring.[citation needed]

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

Boric acid can be used as a colorant to make fire green. For example, when dissolved in methanol it is popularly used by fire jugglers and fire spinners to create a deep green flame much stronger than copper sulfate.
Agriculture
Boric acid is used to treat or prevent boron deficiencies in plants. It is also used in preservation of grains such as rice and wheat.


Boric acid
Formula: BH3O3
Molecular weight: 61.833
CAS Registry Number: 10043-35-3
Chemical structure: BH3O3Other names: Orthoboric acid; H3-BO3; Boracic acid; Boric acid (BH3O3); Boric acid (H3BO3); Borofax; Boron hydroxide; Boron trihydroxide; NCI-C56417;
 Orthoboric acid (B(OH)3); Borsaure; Three elephant; Ant flip; Homberg's salt; B(OH)3; Basilit B; Dr.'s 1 Flea Terminator DF; Dr.'s 1 Flea Terminator DFPBO; Dr.'s 1 Flea Terminator DT; 
Dr.'s 1 Flea Terminator DTPBO; Flea Prufe; NSC 81726; Super Flea Eliminator; Trihydroxyborane; Acidum boricum (Salt/Mix); Bluboro (Salt/Mix); Collyrium Eye Wash (Salt/Mix); 
Collyrium Fresh-Eye Drops (Salt/Mix); component of Aci-Jel (Salt/Mix). 10043-35-3 [RN]
11113-50-1 [RN]
11B Labeled boric acid
13813-78-0 [RN]
234-343-4 [EINECS]
Acide borique [French] [ACD/IUPAC Name]
acidum boricum [Latin]
B(OH)3 [Formula]
Boric acid [ACD/IUPAC Name] [Trade name]
Boric acid-11B
Borsäure [German] [ACD/IUPAC Name]
MFCD00011337 [MDL number]
MFCD00151271 [MDL number]
Orthoboric acid
(10B)Orthoboric acid
11129-12-7 [RN]
12258-53-6 [RN]
12795-04-9 [RN]
1303-86-2 [RN]
13460-50-9 [RN]
13813-79-1 [RN]
14149-58-7 [RN]
1697939 [Beilstein]
7440-42-8 [RN]
Acidum boricum
Ant flip
Boracic acid
Boracic Acid, Orthoboric Acid
Borate (H3bo3)
borate ion
Boric acid ACS grade
Boric acid Electrophoresis grade
Boric acid flakes
Boric acid, biochemical grade
Boric Acid, Granular
Boric acid, NF/USP grade
Boric Acid, Powder
Boric acid-d3
BORIC-11B ACID
Borofax
Boron hydroxide
Boron trihydroxide [ACD/IUPAC Name]
Borsaeure
Borsaure
H3-BO3
Heptaoxotetra-Borate(2-)
Homberg's salt
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:33118
Hydrogen borate [ACD/IUPAC Name]
hydrogen orthoborate
InChI=1S/BH3O3/c2-1(3)4/h2-4H
Kill-off
Kjel-sorb
Orthboric acid
Orthoboricacid
Orthoborsaeure
tetraborate
trihydridoborate
trihydroxidoboron
Trihydroxyborane
Trihydroxyborone
WLN: QBQQ

Boric acid, also known as boracic acid or orthoboric acid, is a naturally occurring compound containing the elements boron, oxygen, and hydrogen (H3BO3). Boric acid crystals are
 white, odorless, and nearly tasteless. It looks like fine table salt in the granular form or like baby powder in the powdered form.

Borates, the general term associated with boron containing minerals such as borax and boric acid, most commonly originate in dried salt lakebeds of deserts or arid areas 
(such as Death Valley, CA, Turkey, and China) or other geographic regions that expose similar deposits (such as the Andes Mountains in South America).

Boric acid crystals were first man-made in 1702 by Wilhelm Homberg who mixed borax and mineral acids with water. The evaporating water left crystals of boric acid and was often 
called “Homberg’s salt.” European researchers soon discovered the compound’s properties as a mild antiseptic and eyewash.

James Wright, a General Electric engineer searching for rubber substitutes during WWII, came upon a remarkable new material by mixing silicone oil with boric acid. The new compound
 had unique properties, acting very much like rubber. It could be stretched to many times its length without breaking and bounced 25% higher than a normal rubber ball. It could even 
pick up the images of most printed material. In 1949 the material was given the name Silly Putty® and it sold faster than any other toy at that time.

Boric acid is one of the most commonly produced borates and is widely used throughout the world in the pharmaceutical and cosmetic industries, as a nutritional supplement, 
flame retardant, in the manufacture of glass and fiberglass, and in the production of wood preservatives to control pests and fungus.During the first world war, a variety of antiseptic solutions were used to treat the wounds of injured soldiers. One of the most common was prepared by dissolving dry sodium carbonate and bleaching powder in tap water, filtering the solution to remove the calcium carbonate that precipitated, and finally adding boric acid, a mild antiseptic. The English organic chemist Henry Dakin described the preparation in the British Medical Journal in August 1915.

A nurse tends to a World War I victim

Source: © Shutterstock

He wrote: ‘the resultant solution contains a balanced mixture of hypochlorite and polyborates of sodium with small amounts of free hypochlorous and boric acids.’

The sodium hypochlorite in the mixture is a powerful antiseptic. ‘The antiseptic action of boric acid has nothing to do with the employment of the acid,’ he noted. Its purpose was to act as a buffer to maintain the pH of the solution. The irritating action of any free caustic alkali formed in the preparation ‘would be at once neutralized by the boric acid or acid borates present in the solution.’

In September 1915, Dakin travelled to the Gallipoli peninsula on board a British hospital ship to test his solution for the treatment of infected wounds sustained by troops fighting in the Dardanelles campaign. Fleet surgeon Frederick Dalton subsequently pointed out in another paper in the British Medical Journal that no other antiseptic was used on the ship: ‘The usual surgical procedures were adopted for enlarging the wound, making counter openings, removing portions of detached bone, foreign bodies, including bits of clothing, fragments of shell, bullets, gravel, etc.’

The hospital ship Anglia

SS Anglia (a hospital ship) in 1915

The wound was then thoroughly irrigated with large quantities of Dakin’s solution. The results were ‘uniformly and consistently good,’ Dalton concluded.

In 1916, Dakin went to northern France to carry out research with French surgeon and biologist Alexis Carrel, who had won the 1912 Nobel prize in physiology or medicine for developing new surgical techniques. They worked together at a temporary hospital in Compiègne. Their treatment of infected wounds involved frequently flushing the surface of the wound with a stream of fresh Dakin’s solution.

Dakin, Dalton and Carrel would undoubtedly have been familiar with the work of English surgeon Joseph Lister in the 19th century. Lister, who is regarded as the father of antiseptic surgery, pioneered the use of phenol, then known as carbolic acid, to clean wounds, sterilise surgical instruments and scrub surgeons’ hands.

He was also an advocate of boracic – or boric – lint as a medical dressing for wounds and ulcers. A book on surgery, published in 1876, includes a chapter by Lister in which he extols the virtues of the lint. It is prepared, he notes, by dipping a piece of lint in a saturated solution of boric acid near boiling point and then allowing it to dry. He writes that it is ‘a fortunate circumstance that the crystals of boracic acid, instead of being hard and harsh, like most crystals, are soft and unctuous, and therefore occasion no mechanical irritation to the skin.’

Boric acid is a white waxy solid that occurs naturally as sassolite, a mineral found in Tuscany in Italy and Nevada in the United States. The acid is manufactured by the reaction of sulfuric or hydrochloric acid with a sodium borate mineral such as borax or kernite, or the calcium borate mineral colemanite.

Boric acid on a light background

Source: © Shutterstock

Boric acid is a white waxy solid that occurs naturally as sassolite

Boric acid has a multiplicity of applications. It is used, for example, as an oxidation catalyst and in the manufacture of cosmetics, domestic insecticides, and fire retardants for textiles.

The acid is poisonous if ingested in large quantities. Brief exposure, however, is less dangerous, according to a fact sheet published by the National Pesticide Information Center in the United States. ‘Boric acid is low in toxicity if eaten or if it contacts skin,’ it notes.

Its use in antiseptic preparations such as Dakin’s solution has declined over recent decades for a variety of reasons. The National Health Service in Britain advises that antiseptics should not be used to clean wounds as they may damage the skin. Tap water or saline solution should be used instead.

I have just looked at the ingredients listed on a bottle of eye wash stored in my medicine cabinet. They include purified water, orange flower water, lavender water, witch hazel water and… boric acid! I then noticed the expiry date on the bottle: June 2008. I’ll have to dispose of it and buy another.

Ben Valsler

That was Mike Freemantle with boric acid. Next time, Katrina Krämer investigates the chemical inspiration behind one of Hitchcock’s greatest works.

Katrina Krämer

The Birds is based on a short story by English author Daphne du Maurier. But Hitchcock might have had another – very real – source of inspiration in the events that happened close to his home in Monterey Bay, California.

Ben Valsler


Regulatory process names
Boric acid
EC Inventory, C&L Inventory, Pre-Registration process
Boric acid, crude natural

Translated names
acid boric, brut natural, cu un conţinut maxim de H3BO3 de 85%, calculat la greutatea substanţei uscate (ro)
C&L Inventory
acide borique (fr)
C&L Inventory
acido borico, grezzo, naturale, contenente non più di 85% di H3BO3 calcolato in base al peso secco (it)
C&L Inventory
aċidu boriku, naturali mhux proċessat, li fih mhux aktar minn 85 fil-mija ta’ H3BO3 ikkalkulat fuq il-piż niexef (mt)
C&L Inventory
boorhape, looduslik toore, H3BO3 sisaldus kuni 85% kuivmassist (et)
C&L Inventory
boorihappo, raaka luonnon boorihappo, joka sisältää enintään 85 % H3BO3 kuivapainosta laskettuna (fi)
C&L Inventory
boorzuur, ruw, natuurlijk, met een gehalte aan H3BO3 van niet meer dan 85 gewichtspercenten, berekend op de droge stof (nl)
C&L Inventory
borna kiselina (hr)
C&L Inventory
boro rūgštis, neapdorota gamtinė, turinti daugiau kaip 85 % H3BO3, skaičiuojant sausos medžiagos masei (lt)
C&L Inventory
borova kislina – surova, naravna, ki ne vsebuje več kot 85 odstotkov H3BO3, računano na suho težo (sl)
C&L Inventory
borskābe, neattīrīta dabīga, satur ne vairāk kā 85% H3BO3 sausnas masā (lv)
C&L Inventory
borsyra, rå, naturlig, innehållande högst 85 viktprocent H3BO3 beräknat på torrsubstansen (sv)
C&L Inventory
borsyre, rå naturlig, indeholdende højst 85% H3BO3, beregnet som tør vægt (da)
C&L Inventory
borsyre, rå, naturlig, som innholder maks. 85 % H₃BO₃ beregnet ut fra tørrvekt (no)
C&L Inventory
Borsäure, natürliche, rohe, mit einem Massenanteil von höchstens 85 % H3BO3 in der Trockensubstanz (de)
C&L Inventory
bórsav, nyers természetes, max. 85% H3BO3–tartalommal, száraz tömegre mérve (hu)
C&L Inventory
kwas borowy, w stanie surowym naturalnym, zawierający nie więcej niż 85% H3BO3 w przeliczeniu na suchą pozostałość (pl)

kyselina boritá, přírodní neupravená, obsahující nejvýše 85 % H3BO3 v sušině (cs)
C
kyselina boritá, surová prírodná, s obsahom nie viac ako 85 % H3BO3 v sušine (sk)

ácido bórico natural em bruto com teor ponderal de H3BO3 não superior a 85 %, calculado em relação ao produto seco (pt)
C
ácido bórico, crudo natural, que contiene no más del 85 % de H3BO3 calculado en peso seco (es)

βορικό οξύ, ακατέργαστο φυσικό, με περιεκτικότητα σε H3BO3 που δεν υπερβαίνει το 85%, υπολογιζόμενη επί ξηράς ουσίας (el)

борна киселина, нерафинирана, натурална, съдържаща не повече от 85 процента H3BO3, изчислени като тегловен процент от сухото вещество (bg)
C&L Inventory

boric acid, crude natural, containing not more than 85 per cent of H3BO3 calculated on the dry weight

Other identifiers
005-007-00-2
C&L Inventory
Index Number
11113-50-1

Name EC / List no. CAS no. Association
Boric acid
EC No. 233-139-2 and EC No. 234-343-4


Boric Acid >
Chemical formula: H3BO3
Material: Boric acid, also called boracic acid or orthoboric acid, is a mild acid often used as an antiseptic, insecticide, flame retardant, glass, wood preservatives, in nuclear power plants to control the fission rate of uranium and as a precursor of other chemical compounds. It has the chemical formula H3BO3. Boric acid is produced mainly from borate minerals by the reaction with sulfuric acid.

Grades: Technical material in both granular and powder forms.

Packaging: Material is available in 25 kilo, 500 kilo, 1000 kilo and 1200 kilo nett bags.

basilit b
  boracic acid
ortho boric acid
  boricacid
  borofax
  boron trihydroxide
  dr.'s 1 flea terminator DF
  dr.'s 1 flea terminator DFPBO
  dr.'s 1 flea terminator DT
  dr.'s 1 flea terminator DTPBO
  flea prufe
  super flea eliminator
  three elephant
  trihydroxyborone


Product Description
Boric Acid

Application Notes
Boric acid is used for weatherproofing wood and fireproofing fabrics; as a preservative; manufacturing of cements, crockery, porcelain, enamels, glass, borates, leather, carpets, hats, soaps, artificial gems; in nickeling baths; cosmetics; printing and dyeing, painting; photography; for impregnating wicks; electric condensers; hardening steel. It is also used as an insecticide for cockroaches and black carpet beetles. It is used In the research labs , astringent, antiseptic, antibacterial and antifungal agent. It is used in buffers and for calibration of polyacrylamide gel columns for the separation of oligonucleotides by capillary electrophoresis.

Usage Statement
Unless specified otherwise, MP Biomedical's products are for research or further manufacturing use only, not for direct human use. For more information, please contact our customer service department.

Key Applications
Buffer component


Boric acid
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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

Preparation
Boric acid is produced mainly from borate minerals by the reaction with sulfuric acid. The largest source of borates in the world is an open-pit mine in Boron, California, USA.

Properties
Boric acid was first prepared by Wilhelm Homberg (1652-1715) from borax, by the action of mineral acids, and was given the name sal sedativum Hombergi ("sedative salt of Homberg"). The presence of boric acid or its salts has been noted in sea-water. It is also said to exist in plants and especially in almost all fruits (A. H. Allen, Analyst, 1904, 301). The free acid is found native in certain volcanic districts such as Tuscany, the Lipari Islands and Nevada, issuing mixed with steam from fissures in the ground; it is also found as a constituent of many minerals (borax, boracite, boronatrocaicite and colemanite).Boric acid is soluble in boiling water. When heated above 170°C it dehydrates, forming metaboric acid HBO2. Metaboric acid is a white, cubic crystalline solid and is only slightly soluble in water. It melts at about 236°C, and when heated above about 300°C further dehydrates, forming tetraboric acid or pyroboric acid, H2B4O7. Boric acid can refer to any of these compounds. Further heating leads to boron trioxide.

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

B(OH)3 + H2O ⇌ B(OH)4− + H+
Ka = 5.8x10−10 mol/l; pKa = 9.24.
Polyborate anions are formed at pH 7–10 if the boron concentration is higher than about 0.025 mol/L. The best known of these is the tetraborate ion, found in the mineral borax:

4B(OH)4− + 2H+ ⇌ B4O72− + 9H2O
Crystal structure
Crystalline boric acid consists of layers of B(OH)3 molecules held together by hydrogen bonds. The distance between two adjacent layers is 318 pm.

Boric-acid-unit-cell-3D-balls.png
Boric-acid-layer-3D-balls.png
the unit cell of boric acid
hydrogen bonding (dashed lines)
allows boric acid molecules to form
parallel layers in the solid state
Toxicology
While strictly speaking, Boric Acid is poisonous if taken internally or inhaled, it is generally not considered to be much more toxic than table salt (based on its mammal LD50 rating of 2660mg/kg body mass).[2]. The Thirteenth Edition of the Merck Index indicates that the LD50 of boric acid is 5.14 g/kg for oral dosages given to rats, and that 5 to 20 g/kg has produced death in adult humans. The LD50 of sodium chloride is reported to be 3.75 g/kg in rats according to the Merk Index. According to the Dutch Health Council(1998/19) Boric Acid should be regarded as if it impairs fertility in humans (R60).

However, it is toxic to unborn infants, and on the testicles of boys. Also, it has been associated with low birth weight, eye malformations and problems with the nervous system.

Uses
Medicinal uses
It can be used as an antiseptic for minor burns or cuts and is sometimes used in dressings or salves or is applied in a very dilute solution as an eye wash. (1.5% solution or 1 tbsp per quart of boiled water has been suggested for the latter.) As an anti-bacterial compound, boric acid can also be used as an acne treatment. Boric acid can be used to treat yeast and fungal infections such as candidiasis (vaginal yeast infections) by inserting a vaginal suppository containing 600 mg of boric acid daily for 14 days (PMID 10865926). It is also used as prevention of athlete's foot, by inserting powder in the socks or stockings, and in solution can be used to treat some kinds of otitis externa (ear infection) in both humans and animals. The preservative in urine sample bottles (red cap) in the UK is boric acid.

Boric acid has the distinction of being the only known acid that is actually beneficial (rather than harmful) to the eyes, and as such is used by ophthalmologists and in some commercial eye drops.

Insecticidal use
Boric acid was first registered as an insecticide in 1948 by the EPA for control of cockroaches, termites, fire ants, fleas, silverfish, and many other insects. [3] It acts as a stomach poison affecting the insects' metabolism, and the dry powder is abrasive to the insects' exoskeleton.

Boric acid may be used either in an insect bait formulation containing a feed attractant or as a dry powder. The powder may be injected into cracks and crevices, where it forms a fine layer of dust. Insects travel through the boric acid dust, which adheres to their legs. When the insects groom themselves, they then ingest the poison, which causes death three to ten days later of starvation and dehydration.

Preservative Use
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 damp 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.

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

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

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

Miscellaneous uses
Borates including boric acid have been used since the time of the Greeks for cleaning, preserving food, and other activities.

Silly Putty was originally made by adding boric acid to silicone oil. Now name-brand Silly Putty also contains significant amounts of elemental silicon (silicon binds to the silicone and allows the material to bounce 20% higher).

Lithium borate is the lithium salt of boric acid and is used in the laboratory as buffer for gel. TBE buffer is widely used for the electrophoresis of nucleic acids and has a higher buffer capacity than a TAE Buffer. It can be used for DNA and RNA polyacrylamide and agarose gel electrophoresis.

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

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

It is also used in India and across the world to dust down Carrom boards to decrease friction and increase speed of play.

Boric acid is also used in special effects. When Boric Acid is combined with an alcohol (usually ethanol), it produces a green flame when burned.


oric acid (H3BO3), also known as [b(OH)3] or H3BO3, belongs to the class of inorganic compounds known as miscellaneous borates. These are inorganic compounds in which the largest
 metallic oxoanion is borate, to which either no atom or a non metal atom is bonded. Boric acid (H3BO3) is a drug. Boric acid (H3BO3) is an extremely weak basic (essentially neutral)
compound (based on its pKa). Boric acid (H3BO3) exists in all living organisms, ranging from bacteria to humans. Outside of the human body, boric acid (H3bo3) is found, on average, 
in the highest concentration in pomegranates. boric acid (H3bo3) has also been detected, but not quantified in, a few different foods, such as figs, french plantains, and redcurrants.
 This could make boric acid (H3bo3) a potential biomarker for the consumption of these foods. It has limited use as an antibacterial agent in caviar. Boric acid (H3BO3) is a potentially
 toxic compound. No indication of carcinogenicity to humans (not listed by IARC). Rinse mouth with water (never give anything by mouth to an unconscious person). INGESTION: do not
 induce vomiting. INHALATION: supply fresh air. Boric acid (H3BO3) also called hydrogen borate, boracic acid,
 Boric acid (H3BO3) is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other chemical compounds. When occurring as
 a mineral, it is called sassolite. If necessary, the person should shower and change contaminated clothing and shoes, and then must seek medical attention.

What is boric acid and its use?

Boric acid (H3BO3) is an antiseptic, pesticide and a weak fungicide. It always be used for insect control, wood preservative in furniture industry, glass industry and also in
 medical field.

What is preservative?

Preservative means any substances that, when added to food, is capable of inhibiting, retarding or arresting the process of decomposition, fermentation or acidification of such 
food but shall not include herb, spice, vinegar or wood smoke.

What are the preservative that allowed in Food Regulations 1985?

Food Regulations 1985 only allowed certain preservatives (sulphur dioxide, benzoic acid; propionic acid, also its sodium, potassium, calcium salt; sodium nitrate, sodium nitrite, 
potassium nitrate and potassium nitrite) and antimicrobial (chlorine dioxide and hydrogen peroxide) in certain food. Hence, oric acid is not included in the list.

Under the Food Law, is it an offence to use boric acid in food and what is the penalty?

Use of boric acid in food violated Sub Section 13 (1) Food Act 1983 which stated that “Any person who prepares or sell any food that has in or upon it any substance which is poisonous, 
harmful or otherwise injurious to health commits an offence and shall be liable, on conviction, to a fine not exceeding one hundred thousand ringgit or to imprisonment for a term not exceeding ten years or to both”.

What are the foods that always contain boric acid?

Although boric acid is not allowed in food, it had been found in pasta type of food such as yellow noodles, kueh teow, laksa, loh se fun, wantan noodles, Hokkien noodles, bee hoon, 
spring roll wrappers and bak chang.

The presence of boric acid in food or food product is due to unethical attitude of some greedy food producer without considering the safety aspect of food to the consumer. Boric acid 
is used by these food producers to extend the product shelf-life and its freshness.

What are the side effects if boric acid present in food?

Individuals who ate food that contained high level of boric acid will experience nausea, vomiting diarrhea, dermatitis, abnormal function of kidney, acute dysfunction of blood circulation
 and death, depends to the level of boric acid absorbed by the body.

How to detect the presence of boric acid in the foods?

Analysis using turmeric water is a crude test to detect the presence of boric acid, however the test is not a confirmatory test. It can give a false positive result. In mee processing 
for example, additional of soda water (Natrium bicarbonate) have been used to get the expected texture. The reaction between soda water and turmeric can cause a changing of color from
 yellow to red. Therefore, the presence of boric acid can only be confirm through lab analysis.

Advise to consumers

Consumers are advised not to use turmeric water as a test to verify the presence of boric acid. Consumers should report to any nearest District Health Ofiice, State Health Department 
or through Food Safety and Quality Division website (http://fsq.moh.gov.my) pertaining to suspicious of boric acid presence in food.


Boric acid Formula
Boric acid is a weak inorganic acid with antiseptic properties, and is also called boracic acid or orthoboric acid.

Formula and structure: The chemical formula of boric acid is H3BO3 (or B(OH)3). Its molecular formula is BH3O3, and its molar mass is 61.83 g/mol. The chemical structure of boric acid is shown below:



The central boron atom is connected to three hydroxyl (-OH) groups, which are capable of strong hydrogen bonding. Its solid crystalline structure consists of parallel layers of boric acid held together in place by hydrogen bonds.

Occurrence: Boric acid occurs naturally in volcanic areas, and in certain minerals such as borax (as sassolite). It is also found in sea water, plants, and fruits in small amounts.

Preparation: Boric acid is prepared by reacting minerals such as borax (Na2B4O7·10H2O), with strong acids like HCl:

Na2B4O7·10H2O + 2 HCl → 4 H3BO3 + 2 NaCl + 5 H2O

It can also be prepared by the hydrolysis of boron trihalides (such as BBr3) or diborane (B2H6):

BBr3 + 3 H2O → B(OH)3 + 3 HBr

B2H6 + 6 H2O → 2 B(OH)3 + 6 H2

Physical properties: Boric acid is a white crystalline solid with a density of 1.435 g/mL, melting point of 170.9 °C and boiling point of 300 °C.

Chemical properties: Boric acid is a weak monobasic acid, and is considered a Lewis acid. It dissolves in boiling water and in anhydrous sulfuric acid. When heated to high temperatures (over 170 °C), it undergoes dehydration to form metaboric acid (HBO2):

H3BO3 → HBO2 + H2O

Uses: Boric acid is non-toxic with antibacterial properties, and it is mainly used as an antiseptic agent, acne treatment, preservative, insecticide, pH buffer, swimming pool chemical, flame retardant, and a precursor to many useful chemicals. It is used industrially for the manufacture of fiberglass, household glass products and the glass used in LCD displays.

Health hazards/ health effects: Low concentrations of boric acid does not pose any toxicity. However, boric acid is poisonous if swallowed or inhaled in large quantities. 
High concentrations of boric acid can potentially lead to reproductive problems. Exposure to boric acid over long periods of time can cause possible kidney damage


 
 
 
 
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