Talk:Boric acid

B(OH)₄⁻

What is the name of the anion B(OH)₄⁻? I can't find a definitive answer anywhere! The only name I've seen is borate, but that is also used to refer to BO₃³⁻. The only reason I want to know is because I've made an image of the structure of this anion and before I can upload it, I need to give it a filename!

Cheers

Ben 22:43, 27 December 2006 (UTC)

According to CAS: CA Index Name: Borate(1-), tetrahydroxy- (9CI); Other Names: Borate (BO45-), tetrahydrogen (8CI); Borate (B(OH)41-); Tetrahydroxoborate(1-); Tetrahydroxyborate(1-).

My favorite among those would be tetrahydroxyborate. Itub 23:17, 27 December 2006 (UTC)

The "bible" (Holleman and Wiberg) also say tetrahydroxyborate. It explains that B(OH)3 (orthoboric acid, also called boric acid) is a very weak Lewis acid (not Bronsted) and apparently picks up the extra hydroxide somewhat reluctantly.--Smokefoot 23:27, 27 December 2006 (UTC)

Good stuff. Thanks, gentlemen. I have, accordingly, created the article tetrahydroxyborate. See if you might like to contribute to it.

Ben 23:49, 27 December 2006 (UTC)

What makes you think that BO₃³⁻ actually exists? Both boric acid and borate explain that H₃BO₃ does not dissociate protolytically: the acid equilibrium is:

B(OH)₃ + H₂O ⇌ B(OH)₄⁻ + H⁺

K_a = 5.8x10⁻¹⁰ mol/l; pK_a = 9.24.

NaB(OH)₄ is stoichiometrically equivalent to NaBO₂·2H₂O, and will dehydrate to sodium metaborate if you heat it strongly enough. But sodium borate is not Na₃BO₃, at least as far as I've ever seen (although a fusion of the mixed oxides would be quite interesting: it would probably give... a mixed oxide!) Physchim62 (talk) 00:17, 28 December 2006 (UTC)

I read this in Greenwood & Earnshaw:

monomeric triangular BO₃ units exist in rare-earth orthoborates, M^IIIBO₄

so I assumed BO₃³⁻, whether it really exists or not aside, was named orthoborate.

Would it not be possible to form BO₃³⁻ fleetingly in the gas phase? If so, the species would need a name.

Even if BO₃³⁻ doesn't exist, that doesn't necessarily mean B(OH)₄⁻ assumes the title borate. Considering the immense structural diversity of boron oxoanions, I thought a common one like B(OH)₄⁻ would have its own distinct name.

At least I had a term to name my images and the article!

Ben 00:49, 28 December 2006 (UTC)

FWIW, BO₃³⁻ is listed by Chemical Abstracts as "borate" (also "orthoborate") and has its own registry number. I don't know for sure under which conditions it exists, but certainly tetrahydroxyborate is a less-ambiguous name for B(OH)₄⁻. Itub 00:57, 28 December 2006 (UTC)

Fair enough, more details for borate then :) ! Physchim62 (talk) 07:28, 28 December 2006 (UTC)

Ortho boric acid: toxicity?

The article mentions that boric acid is also known as orthoboric acid, and provides the formula H₃BO₃. Then it goes on to mention a couple other substances that are formed by heating boric acid to very high temperatures, and says they are also known as boric acid. This brings me to two questions:

1. Is ortho boric acid the same as H₃BO₃, or is it a different form of boric acid?
2. Is ortho boric acid as safe as, or safer than, or less safe than other commonly-used pesticides, such as indoor pyrethrin-based insecticides? Is the toxicity of boric acid more specific (to invertebrates or arthropods) or less specific than that of the pyrethrin derivatives?

69.140.164.142 02:06, 15 April 2007 (UTC)

1. Orthoboric acid is the same as H₃BO₃: it is by far the commonest form of boric acid, and the only one that most people are likely to come accross.
2. Orthoboric acid is about as safe as insecticides come (although the same could be said for pyrethroids in household preparations). It does have a measurable toxicity to mammals, particularly if it can get directly into the bloodstream (see the note at the top of this talk page), but it is relatively low. It is considered safe enough to be permitted as a preservative in foods in the European Union (number E284), but not, I believe, in the U.S. Pyrethroids are pretty non-toxic to humans as well, although they can cause asthma in sensitive indviduals. Both boric acid and pyrethroids can be irritating to the skin, especially on prolonged or repeated contact, and for this reason it is a good idea to wash your hands after using either chemical (any chemical, in fact). As with all household chemicals, they should be stored well out of reach of children.

Hope this answers your query. Physchim62 (talk) 02:59, 15 April 2007 (UTC)

When comparing the toxicity of Boric acid to other insecticides (pyrethrum and pyrethroids) you may be trying to compare apples to oranges. When talking of using BA powder as an insecticide it will be at 97%-99% strength, where the pyrethrum or pyrethroid products will contain only a fraction of one percent of the active ingredient. So the "insecticide" boric acid powder can be 50 to over 200 times more toxic than the "insecticide" using a pyrethrum or pyrethroid as the active ingredient. —Preceding unsigned comment added by 76.182.238.19 (talk) 06:39, 29 January 2008 (UTC)

I invite you fellow editors to read the EPA TRED on the topic. Testicular toxicity in dogs has been noted at fairly low concentrations (32 mg/kg bw/day) after 90 days. 04:02, 5 February 2008 (UTC) —Preceding unsigned comment added by Observer31 (talk • contribs)

That is not a "low concentration" — it corresponds to more than two grams per day for an adult male! Most substances are toxic at such doses. Physchim62 (talk) 13:45, 5 February 2008 (UTC)

Ah, but are humans more or less sensitive than dogs? We don't know. Are some individuals more sensitive than others due to genetic diversity? Most probably. What about small kids who weight a lot less than adults? A 10 kg kid would only need to ingest 320 mg! This is why safety factors are needed, and this is why limits had to be put boric acid use in pools. Again, read the TRED. This is a work in progress for me and I should hopefully have more documentation to put soon. For example, it seems that rats are particularly resistant to boric acid poisoning, and that other mammalian species are much more sensitive to it. I'm not going to put this on the main page for now as I don't have the documentation, but again, hopefully I will be able to back this up soon. Observer31 (talk) 03:57, 6 February 2008 (UTC)

Christopher H. Linden a; Alan H. Hall b; Kenneth W. Kulig b; Barry H. Rumack b (1986). "Acute ingestions of boric acid". Clinical Toxicology. 24 (4): 269–279. doi:10.3109/15563658608992592.{{cite journal}}: CS1 maint: multiple names: authors list (link) states that serveral incidents with upto 297 grams per person makes it unlikely that there is acute poisoning with a single uptake is possible.--Stone (talk) 15:41, 10 February 2008 (UTC)

Michael P. Dieter (1994). "Toxicity and Carcinogenicity Studies of Boric Acid in Male and Female ${\rm B}6{\rm C}3{\rm F}_{1}$ Mice". Environmental Health Perspectives. 102 (7 Supplement 7: Health Effects of Boron): 93–97. doi:10.2307/3431970. states that upto 1000 mg/kg per day lead to effects, but no significant death.--Stone (talk) 15:45, 10 February 2008 (UTC)--Stone (talk) 19:26, 10 February 2008 (UTC)

Silly Putty - "elemental silicon"

"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)."

Does anyone have a source for this? Presumably a gray, metallic powder would be visible in the Silly Putty if silicon was present. Also, elemental silicon is protected by a surface oxide layer, and would probably not bind to the silicone. Even if it did, it seems unlikely that it would result in a higher bounce.

The same statement is repeated on the Silly Putty page, however, the formula listed there gives no mention of elemental silicon. Unless someone can back up this statement, I will remove it from both articles shortly. --Pyrochem 19:31, 26 July 2007 (UTC)

Fire Spinning reference

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

I've added in a reference for this, from a Home of Poi article; Home of Poi is linked from the Poi (juggling) page, as "one of the largest and most influential poi communities in the world". Nacbrie 19:01, 31 October 2007 (UTC)

copyvio from beyondpesticides.org

I removed a paragraph which appeared to be lifted verbatim from beyondpesticides.org and seems to be a copyvio. Re-instate if there is some evidence to the contrary.

The page at beyondpesticides.org cites its sources (and we do not, in this case), and is also referenced by another site. Both of these I take to be evidence (not proof) that the beyondpesticides.org version of that paragraph came first (the addition on wikipedia was from September).

• The original page: http://www.beyondpesticides.org/infoservices/pesticidefactsheets/leasttoxic/boricacid_borates_borax.htm
• The reference to the original page: http://www.expertvillage.com/article/1769_boric-acid-cockroaches.htm

The paragraph in question started with: "Boric acid may be used either in an insect bait formulation containing a feed attractant..." Jun-Dai (talk) 16:15, 5 February 2008 (UTC)

What does Goodman and Gilman say about this?

71.114.163.227 suggested we look this up in a textbook such as Goodman and Gilman's Pharmacological Basis of Therapeutics; although I see that the concerns about toxicity have already been addressed, I think that it would be nice if somebody would please consult that source and see what it says about the content of this article. 69.140.152.55 (talk) 12:12, 19 May 2008 (UTC)

The US NIOSH have kidly published the RTECS record for boric acid here. Physchim62 (talk) 18:03, 19 May 2008 (UTC)

The textbook would be a useful secondary source, if somebody were to consult it and update the article based on its content. 69.140.152.55 (talk) 20:18, 8 August 2008 (UTC)

So I looked it up on Amazon "search inside". It reads: "Boric acid, a common household chemical, forms a complex with riboflavin and promotes its urinary excretion. Boric acid poisoning, therefore, may induce riboflavin deficiency." Is that it? If so, I propose to remove the title from "Further reading", and the tag calling for the material to be included. --Old Moonraker (talk) 20:40, 8 August 2008 (UTC)

WP article: Goodman & Gilman's The Pharmacological Basis of Therapeutics. --Old Moonraker (talk) 21:01, 8 August 2008 (UTC)

Controversy surrounding 11-M Madrid bombings

I think a new section, or maybe a new page should be written about this. An amount of boric acid found in the house of one of the terrorists involved in the bombings suppossedly linked him to ETA. That wasn't considered important during the trial, and some think this information has been dismissed on purpose to hide connections between Al-Qaeda, ETA and even the current goverment. (This is thought by die-hard rightists who support Aznar's goverment and consider that 11-M was some sort of coup)

There's already a page about it in Spanish, but not in English, as far as I know.

http://es.wikipedia.org/wiki/Caso_del_informe_sobre_el_%C3%A1cido_b%C3%B3rico —Preceding unsigned comment added by 81.38.245.104 (talk) 19:17, 14 August 2008 (UTC)

Eti Mine Works Borate Mine or Bank/Insurance?

The article says Eti Mine Works is a large mine - it hot links to an article that says that Eti Mine Works is a bank and insurance company...? Paulburnett (talk) 20:13, 5 September 2008 (UTC)

Boric acid, at the same ld50 as pyrethroid, is much less toxic to marine animals. What is worse is the surfactant (dtergent) that is used to emulsify the pyrethroid, and to distribute it. The surfactant is often more toxic than the pyrethroid. In Friday Harbor, WA, we are seeing major damage to nearshore animals from pyrethroids and surfactants in stormwater, which is not treated. Mikie

Extraction of boron

I know that boron is extracted from this mineral. Can a chemist please write something about boron's extraction from this? Thank you. —Preceding unsigned comment added by Suryamp (talk • contribs) 17:11, 27 January 2010 (UTC)

Acidity

pKa1 is 5.2 or 9.24 Ka2 & Ka3 is respectively 4*10^-13 & 4*10^-14. 113.22.176.107 (talk) 10:39, 3 April 2010 (UTC).

ECHA Classification

The wikipedia article states that the ECHA changed their classification Boric Acid to highly toxic and gives a reference to a document published by ECHA. However, upon examination the document actually states May damage fertility. May damage the unborn child. I'm going to change the text in the article to accurately reflect the situation. --Popoi (talk) 19:45, 22 February 2011 (UTC)

EU legislation now requires it to be labelled "toxic to reproduction" and prohibits supply to the general public — Preceding unsigned comment added by 91.213.110.4 (talk) 14:33, 2 October 2013 (UTC)

Decomposes below the boiling point??

Here we can read, that it decomposes above 170 deg C to B2O3 and H2O. In the table there is not only the melting point given, but also a boiling point which is with 300 deg C well above the decomposition temperature. How is this possible? Are these extrapolated values from low pressure conditions? Are there any references for these values? (I found the 170 deg decomp as well, in the Hollemann/Wiberg 101. ed). --188.23.115.23 (talk) 15:06, 7 October 2011 (UTC)

Yes, there is a contradiction between the article and the infobox. The Properties section describes decomposition reactions at 170oC and also at about 300oC. If this is correct, these temperatures should not be defined as melting and boiling point in the infobox, or should at least have the notation "dec".

However we need proper sources before deciding which is correct. At the moment there are no references for either the decomposition reactions in the Properties section, or the "melting point" and "boiling point". Sources please. Dirac66 (talk) 16:15, 7 October 2011 (UTC)

You do realize that it is not a point event, the compound does not decompose 100% before heating to a higher temperature. If the compound is heated rapidly enough, it will melt. Octasulfur decomposes above 109 degrees, but melts at 115. Plasmic Physics (talk) 21:26, 7 October 2011 (UTC)

Hmm, I had not thought of rate-dependent processes, which could reconcile the two statements. You may be right, but I find it suspicious that the infobox melting and boiling points correspond exactly to the decomposition temperatures of the article. However, I have not been able to find the correct information in my books, so I am hoping you have a source for your statements. If so, we can add the required explanations and give a reference. Dirac66 (talk) 03:00, 8 October 2011 (UTC)

How one makes a solution of borax & boric acid with a high solubility

This article claims:

'Boric acid, mixed with borax (sodium tetraborate decahydrate) at the weight ratio of 4:5, is highly soluble in water'

The article which it references says:

'the solution prepared by dissolving 20 g of boric acid and 25 g of borax into 100 g of hot water over 80 °C did not recrystallize at 20 °C.'

and:

'It should be noted that the mixture of boric acid and borax does not dissolve into water at room temperature to the level of the highly concentrated solution. This is considered to be due to the problem of kinetics.'

In other words one can't mix them 4:5 with room temperature water and have them go into solution. The person who wants to make this solution needs this information. The article isn't in the public domain: one must either pay for it, have a subscription to the journal, or go to a institution which has a subscription (what I did).

RussellBell (talk) 23:27, 30 December 2012 (UTC)

Good point. Since you have read the reference, could you suggest what changes should be made to the article to make it more useful? (preferably without looking at the reference while you write, so that you do not use the same words and violate copyright) Dirac66 (talk) 00:20, 31 December 2012 (UTC)

Boric acid mattress treatments and its health concerns

Some mattresses are treated with boric acid powder in order to meet flame retardant regulations. This of course raises health concerns, but from what I understand boric acid is one of the least toxic 'treatments' available (As opposed to synthetic chlorinated and brominated chemicals). I didn't look for solid references, but I hope someone is inspired to do so, and add this topic to the page.

Love and Light! Joe* Bit spark (talk) 17:39, 7 January 2013 (UTC)

Source needed for Bronsted acidity

Question to Plasmic Physics: Do you have a source for your recent claim that Boric acid dissociates in aqueous solution as a triprotic Brønsted acid, and for the three equiiibrium constant values K_a1, K_a2, K_a3? After your edit, the article appears to reference Jolly p.198 for both the Lewis and Bronsted acidity. However I have Jolly open in front of me and it in fact says that B(OH)₃ does not lose a proton upon ionization; it abstracts a hydroxide ion from water. The only equation given is the one which forms B(OH)₄^- with K = 5.8 x 10^-10. (not 7.3 x 10^-10 as in the article now).

A more recent source is Housecroft and Sharpe (2nd ed. p.314-5) which says In aqueous solution, B(OH)3 behaves as a weak acid, but is a Lewis rather than Bronsted acid. The chemical equation has an H₂O added to each side which is strictly more correct, and pKa is given as 9.1 (corresponding to Ka = 7.9 x 10^-10. So that is two sources for no Bronsted acidity; we need your source for claiming Bronsted acidity so that we can assess its reliability and decide whether or not to mention both opinions. Dirac66 (talk) 02:06, 29 August 2013 (UTC)

Done. (A courtesy from DMacks.) Plasmic Physics (talk) 03:29, 29 August 2013 (UTC)

Thank you. I have now read the article by Perelygin and Chistyakov which you cite. There appears to be a genuine disagreement between their article and the two inorganic books mentioned above as to whether boric acid is a Bronsted acid. Since none of the three sources addresses the question of why there is a disagreement (or even mentions the disagreement), I think that WP:NPOV requires that we mention both viewpoints and maintain neutrality as to which is correct. I will rewrite this section accordingly.

Part of the problem is that we seem to have incomplete evidence for both sides of the argument. Jolly mentions Raman evidence for B(OH)₄^- but excludes the possibility of deprotonation without saying why. Perelygin and Chistyakov give equilibrium constants for the three deprotonation steps, but does not say how they were measured or mention spectroscopic or other evidence for BO(OH)₂^- etc. It might help to check their references (two Russian handbooks and a Russian encyclopedia) and find the original source for the numbers, but that task requires someone who can access and read the Russian literature. Dirac66 (talk) 23:09, 1 September 2013 (UTC)

I've given the Pelelygin's sources a very quick look:

Lur'e has only K₁=5.8×10^-10. It doesn't have inline citations (in fact, it doesn't even have a complete references list)

Knunyants has K₁=5.8×10^-10, K₂=4×10^-13, K₃=4×10^-14. It claims the acid releases free H⁺. The only document it calls a source doesn't have these numbers (it only says pKa for the first step is 9).

Glinka has K₁=6×10^-10, K₂=2×10^-13, K₃=2×10^-14 (at 20°C). No references list.

Hopefully, this is helpful.--R8R Gtrs (talk) 12:38, 2 September 2013 (UTC)

Alphabetical order for uses?

Would it help readers if the ==Uses== section was arranged alphabetically by ===subsection=== title? R Ge B (talk) 00:14, 20 March 2014 (UTC)

Changed pKa to resemble Sulfuric acid and Phosphoric acid

In the info box, I have changed "9.24 (see text)" to "9.24, 12.4, 13.3", the format used in Sulfuric acid and Phosphoric acid. There are good reasons for the 'see text' note, but it's not clear what part of the text is meant. It could refer to Lewis acidity, or it could refer to the section discussing boric acid in solution with other species (as in natural waters).

The articles on the other polyprotic acids simply list the values; it should be clear to a reader with knowledge of the concept of the dissociation constant that this refers to pK_a1, pK_a2 and pK_a3, and the solvent is water. pK_a by definition refers to Brønsted acidity, so the Lewis acidity discussed in the article should not impact the values given here.

Some readers probably come to this article just for the pK_a and other basic properties. Some possibilities for presenting the acidity: - Keep this version (with 3 values) - Revert to "see text", but with a link to the intended section - Provide just the first dissociation constant - Indicate the mixed Lewis/Brønsted acidity in the infobox (may be too technical for some readers)

Roches (talk) 04:32, 20 June 2014 (UTC)

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LD50, About units / SI

2,660 mg/kg, 5.14 g/kg, 5 to 20 g/kg, 3.75 g/kg, 2–3 g in infants, 5–6 g in children, and 15–20 g in adults, poisonings with boric acid (10–88 g) reported no fatalities. I changed the 2,660 mg/kg to 2.66 g/kg, for a clearer comparison between the data. Change was denied, and it makes no sense to me as why. 84.251.181.39 (talk) 18:20, 14 January 2017 (UTC)

Unsupported material

However, other sources say that boric acid is also a tribasic Brønsted acid, with successive ionization steps and acidities as follows:

B(OH)₃ ${\ce {<<=>}}$ BO(OH)⁻
₂ +  H⁺ (K_a1 = 5.8x10⁻¹⁰; pK_a1 = 9.24)

(a1)

BO(OH)⁻
₂ ${\ce {<<=>}}$ BO₂(OH)²⁻ +  H⁺ (K_a2 = 4x10⁻¹³; pK_a2 = 12.4)

(a2)

BO₂(OH)²⁻ ${\ce {<<=>}}$ BO³⁻
₃ +  H⁺ (K_a3 = 4x10⁻¹⁴; pK_a3 = 13.3)

(a3)

Since the value of Ka1 is comparable to that of the reaction with OH−, the concentrations of BO(OH)−
2 and B(OH)−
4 are similar.

I have removed the above items from the main article for the following reason: The paper reporting these species is purely theoretical. The abstract reads "pH ranges of existence of boric acid and its ionic species H₂BO₃⁻ , HBO₃²⁻ , BO₃³⁻ , and B(OH)₄⁻ in aqueous solutions are calculated using Mathcad software package." This is speculation, not supported by any physical evidence. Petergans (talk) 12:41, 20 July 2018 (UTC)

References

Boric acid as insecticide

Note that Boric acid exists as a fine powder of slippery plates (ala graphite, wiki notes lubrication properties) so the "cut up the insect like glass" doesn't make sense. The lit says roaches acquire a static charge while moving and the powder (c.f. diatamaceous earth) sticks to their bodies being ingested on insect self-cleaning actions AND entry into and blockage of insects spiracles preventing respiration. Many animals and birds take "dust baths" to relieve themselves of arthropod parasites in the same manner. 96.89.150.123 (talk) 00:45, 11 March 2020 (UTC)

Toxicity and food preservation

Sir/ma'am, if boric acid is toxic,supposed to be carcinogenic and even used as insecticide, why is it used as a food preservative? Won't it increase the chances of disease? Vanshita poddar (talk) 19:40, 18 April 2020 (UTC)

Mouthwash

Boric acid used to be a part of the formula for Listerine mouthwash. This was changed in the '70s or '80s, when boric acid was replaced by Poloxamer 407. Was Warner Lambert forced to change it, or did they do so on their own accord? rlongman1 24.45.154.41 (talk) 22:08, 21 May 2021 (UTC)

Chemical structure

The chemical structure for boric acid is BOOH. It is an acid. Its structure is not B(OH)3. That is the hydrated form of boric acid. My Flatley (talk) 01:59, 8 December 2020 (UTC)

Isn't BO₂H specifically metaboric acid? Our article here notes "The term boric acid may sometimes refer to any of these compounds". Looking at the cited refs, that formula is always called "meta..." whereas simply "boric acid" seems to B(OH)₃ whenever it is refering to a single compound. DMacks (talk) 03:52, 8 December 2020 (UTC)

That's not how covalent bonds work

Boron is in group 3. This means that Boron would require 5 covalent bonds to be electronically stable. However, there is only 3 covalent bonds shown on the boron in the graphic.

I am going to assume that you want ionic bonds. This would not be B(OH)₃, that would be B⁺³(OH)⁻₃. 91.240.227.220 (talk) 11:08, 30 November 2022 (UTC)

Your premise is not correct. While there are multiple kinds of "electronic stability", putting 5 bonds on a group 3 element would make it have a charge of –2 and an exceeded octet. DMacks (talk) 15:47, 30 November 2022 (UTC)

You have stumbled across some of complexity and subtlety of chemical bonding that is often omitted from introductory chemistry teaching. I think what you mean is boron is in group 3, therefore it has 3 valence electrons and requires 5 more to achieve a full outer shell of 8 electrons according to the octet rule. Boron could do that by forming 4 bonds, not 5. But it doesn't have to do that to be stable. The fact is boric acid is stable with only 3 formal covalent bonds at boron. It's not this article that's wrong, it's treating the octet rule as inviolable rather than a rule of thumb that has many exceptions. Boric acid is one of them, and boron compounds provide many others. These exceptions are useful, as shown by organoboron chemistry or frustrated Lewis pairs, for example.

For starters, the 3-coordinate, trigonal planar structure of boric acid presented in this article is backed up by experimental evidence: see Boric acid#Molecular and crystal structure for details. You don't have to take my word for it.

Why is boric acid able to break the octet rule? Boron#Atomic structure offers something of an explanation for the stability of boric acid and other 3-coordinate, electronically and coordinatively unsaturated boron species. It alludes to the typical textbook explanation: donation of electron density from filled π orbitals on adjacent atoms stabilises the empty boron p orbital, as described at Boron trifluoride#Structure and bonding. As discussed at Talk:Boron trifluoride#Covalent or ionic?, in some cases a better explanation that doesn't involve π donation is this: remaining 3-coordinate and planar avoids the destabilisation of the existing bonds that would occur if a bond to a fourth atom were to form. This explanation makes sense for boron species with ionic or highly polar covalent bonding. In boron compounds without π donation or ionic/strongly polar bonds, you observe other ways of stabilising the vacant boron p orbital. For example, borane tends to aggregate to diborane or other boranes unless it encounters a Lewis base and forms an adduct.

I said boron could form 4 bonds to complete its octet and that does sometimes happen. As you can see in Boric acid#Aqueous solution, boric acid is able to act as a Lewis acid by accepting an electron pair from a Lewis base to form 4-coordinate, tetrahedral species. An example is boric acid's reaction with hydroxide to form tetrahydroxyborate:

B(OH)₃ + OH⁻ → B(OH)−4

These 4-coordinate boron species are not necessarily more stable than the 3-coordinate ones, so you tend to see equilibria between the two. Ben (talk) 19:56, 30 November 2022 (UTC)