Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 215-125-8
CAS number: 1303-86-2
on boron chemistry of environmental relevance
is almost exclusively found in the environment in the form of
boron-oxygen compounds, which are often referred to as borates.
The high strength of the B-O bond relative to those between boron
and other elements makes boron oxide compounds stable compared to
nearly all non-oxide boron materials. Indeed, the B-O bond is
among the strongest found in the chemistry of naturally occurring
substances. As a result of the high relative stability of boron
oxides compared to other boron compounds they are the
thermodynamically favoured decomposition products. This is an
inescapable outcome of the laws of thermodynamics.
virtually all boron compounds ultimately decompose under
environmental conditions to the thermodynamically most stable
state represented by boric acid, many boron compounds exhibit high
kinetic stability and decompose extremely slowly under
environmental conditions - in some cases so slowly that they can
be regarded chemically inert for practical purposes.
Inorganic borates (e.g., boric acid, sodium
tetraborates) are soluble in water. The chemical species present in
solution depend on concentration and pH.
Only two soluble boron species in ordinary
soils can be expected (Adriano, 2001). The nonionized species, [B(OH)3],
is the predominant species expected in soil solution. Boric acid, [B(OH)3],
is a very weak, monobasic acid that acts as a Lewis acid by accepting a
hydroxyl ion to form the borate anion, [B(OH)4]-.
At pH greater than 9.2, [B(OH)4]- becomes
B(OH)3 + 2H2O ↔ [B(OH)4]-
+ H3O+ pKa = 9.2
In the pH range of 7 to 11, both species can
be found. With higher boron concentrations (B > 0.025 M) and increasing
pH also polymeric boron forms can also precipitate, which are usually
very rare and unstable in soils. Therefore, boric acid and borate ions
are the predominant B-forms in the natural soil system (Power and Woods,
1997; de Vette et al., 2001).
Boron as a natural element is not
degradable. However, boron and its inorganic compounds are subject to
chemical transformation processes (adsorption, complexation,
precipitation, fixation) once released to the environment. One
consequence of the transformation is that the mobility/bioavailability
and the potential for toxicity, induced by the borate species, is
changed and in many cases reduced or even removed over time. Thus, these
natural processes achieve a similar result as is sought in the
demonstration of biotic and abiotic degradation of synthetic organic
Please also refer to the read-across
statement attached to section 13.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
Welcome to the ECHA website. This site is not fully supported in Internet Explorer 7 (and earlier versions). Please upgrade your Internet Explorer to a newer version.
Do not show this message again