Registration Dossier
Registration Dossier
Data platform availability banner - registered substances factsheets
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
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: 233-139-2 | CAS number: 10043-35-3
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2010-06-02 - 2010-06-24
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Deviations:
- not specified
- GLP compliance:
- yes
- Dissociating properties:
- yes
- pKa:
- 8.94
- Temp.:
- 20 °C
- Remarks on result:
- other: Overall standard deviation = 0.22; overall % RSD = 2.45
- Conclusions:
- The test substance was analysed for dissociation constant according to OECD Test Guideline 112. The mean dissociation constant (pKa) was found to be 8.94.
- Executive summary:
The dissociation constant of the test-item was determined in a GLP-conform study according to OECD duideline 112. The mean dissociation constant (pKa) was found to be 8.94.
Reference
Test item determination 1:
Weight of test item taken (g) = 0.1547
Molecular weight of test item = 61.84
Final volume of solution made up in carbon dioxide-free distilled water (mL) = 250.
Concentration of test item solution (M) = 0.1547/61.84 x 1000/250 = 0.010006
NB in the absence of a certificate of analysis for the test item, the calcualtions of test item solution concentration the purity of the test item has been assumed to be 100 %
Volume of test item solution taken for titration = 50 mL.
Volume of 0.1 M sodium hydroxide added (mL) |
pH of solution |
pKa |
0.0 |
6.55 |
N/A |
0.4 |
8.08 |
9.14 |
0.8 |
8.43 |
9.15 |
1.2 |
8.63 |
9.14* |
1.6 |
8.78 |
9.11* |
2.0 |
8.91 |
9.9* |
2.4 |
9.05 |
9.09* |
2.8 |
9.16 |
9.06* |
3.2 |
9.27 |
9.03* |
3.6 |
9.37 |
8.97* |
4.0 |
9.48 |
8.90* |
4.4 |
9.60 |
8.77* |
4.8 |
9.72 |
8.43* |
5.2 |
9.84 |
N/A |
5.6 |
9.99 |
N/A |
6.0 |
10.16 |
N/A |
6.4 |
10.37 |
N/A |
6.8 |
10.69 |
N/A |
7.2 |
10.99 |
N/A |
7.6 |
11.27 |
N/A |
8.0 |
11.43 |
N/A |
Mean (using values marked * only) = |
8.96 |
|
SD (using values marked * only) = |
0.22 |
|
%RSD = |
2.44 |
Test item determination 2:
Weight of test item taken (g) = 0.1548
Molecular weight of test item = 61.84
Final volume of solution made up in carbon dioxide-free distilled water (mL) = 250.
Concentration of test item solution (M) = 0.1548/61.84 x 1000/250 = 0.010013
Volume of test item solution taken for titration = 50 mL.
Volume of 0.1 M sodium hydroxide added (mL) |
pH of solution |
pKa |
0.00 |
6.55 |
N/A |
0.4 |
8.04 |
9.11 |
0.8 |
8.42 |
9.15 |
1.20 |
8.62 |
9.13* |
1.6 |
8.77 |
9.10* |
2.0 |
8.89 |
9.07* |
2.4 |
9.00 |
9.04* |
2.8 |
9.12 |
9.02* |
3.2 |
9.22 |
8.98* |
3.6 |
9.33 |
8.93* |
4.0 |
9.43 |
8.85* |
4.4 |
9.53 |
8.70* |
4.8 |
9.64 |
8.35* |
5.2 |
9.76 |
N/A |
5.6 |
9.90 |
N/A |
6.0 |
10.03 |
N/A |
6.4 |
10.21 |
N/A |
6.8 |
10.43 |
N/A |
7.2 |
10.72 |
N/A |
7.6 |
11.03 |
N/A |
8.0 |
11.26 |
N/A |
8.4 |
11.43 |
N/A |
8.8 |
11.55 |
N/A |
9.2 |
11.66 |
N/A |
9.6 |
11.74 |
N/A |
10.0 |
11.80 |
N/A |
10.4 |
11.87 |
N/A |
10.8 |
11.92 |
N/A |
11.2 |
11.96 |
N/A |
Mean (using values marked * only) = |
8.92 |
|
SD (using values marked * only) = |
0.24 |
|
%RSD = |
2.65 |
Test item determination 3:
Weight of test item taken (g) = 0.1546
Molecular weight of test item = 61.84
Final volume of solution made up in carbon dioxide-free distilled water (mL) = 250.
Concentration of test item solution (M) = 0.1546/61.84 x 1000/250 = 0.010000
Volume of test item solution taken for titration = 50 mL
Volume of 0.1 M sodium hydroxide added (mL) |
pH of solution |
pKa |
0.00 |
6.33 |
N/A |
0.4 |
8.08 |
9.14 |
0.8 |
8.39 |
9.10 |
1.20 |
8.60 |
9.11 |
1.6 |
8.77 |
9.10 |
2.0 |
8.90 |
9.08 |
2.4 |
9.02 |
9.06 |
2.8 |
9.14 |
9.04 |
3.2 |
9.25 |
9.01 |
3.6 |
9.35 |
8.95 |
4.0 |
9.47 |
8.89 |
4.4 |
9.57 |
8.73 |
4.8 |
9.69 |
8.39 |
5.2 |
9.82 |
N/A |
5.6 |
9.98 |
N/A |
6.0 |
10.19 |
N/A |
6.4 |
10.40 |
N/A |
6.8 |
10.72 |
N/A |
7.2 |
11.08 |
N/A |
7.6 |
11.32 |
N/A |
8.0 |
11.46 |
N/A |
8.4 |
11.58 |
N/A |
8.8 |
11.68 |
N/A |
9.2 |
11.75 |
N/A |
9.6 |
11.83 |
N/A |
10.0 |
11.88 |
N/A |
10.4 |
11.93 |
N/A |
10.8 |
11.98 |
N/A |
11.2 |
12.01 |
N/A |
Mean (using values marked * only) = |
8.94 |
|
SD (using values marked * only) = |
0.22 |
|
%RSD = |
2.50 |
Description of key information
A study conducted according to OECD guideline 112 gave a dissociation constant for boric acid of 8.94 at 20 ºC. The dissociation behaviour is also described in several publications.
Boric acid is a Lewis acid (hydroxide ion acceptor) rather than a Brønsted acid (proton donator). For this purpose the formula for boric acid is best written as B(OH)3.
pKa = 9.0 at 25 ºC for boric acid in dilute solutions only (B ≤ 0.025 M).
At higher boron concentrations, polynuclear complexes are formed and several dissociation/formation constants apply.
Key value for chemical safety assessment
- pKa at 20°C:
- 8.94
Additional information
At low boron concentrations (B ≤ 0.025 M) the following equilibrium is found
B(OH)3+ 2H2O«[B(OH)4]-+ H3O+
pKa = 9.0 at 25 °C
pKa = 8.94 at 20 °C
Although at these concentrations, boric acid exists as undissociated boric acid B(OH)3at pH < 5, whereas at pH > 12.5 the metaborate ion -[B(OH)4]-- becomes the main species in solution. Both species are present at pH 5-12.5 at concentrations B ≤ 0.025 M.
At higher boron concentrations (B > 0.025 M) an equilibrium is formed between B(OH)3, polynuclear complexes of B3O3(OH)4-, B4O5(OH)42-, B3O3(OH)52-, B5O6(OH)4-and B(OH)4-. In short:
B(OH)3 «polynuclear anions«B(OH)4-.
Again, pH<5, boron is mainly present at B(OH)3and in alkaline solution at pH>12.5, boron is mainly present as B(OH)4-. At in between values (pH 5-12) polynuclear anions are found as well as B(OH)3and B(OH)4-.
The dissociation constant depends upon temperature, ionic strength and presence of group I metal ions (Na, K, Cs).
In the presence of metal ions (e.g. Na, Mg, Ca) ion-pair complexes are formed, which further reduce the undissociated boric acid concentration:
Mn++ B(OH)4-«MB(OH)4(n-1)+
These ion pair complexes are expected to be present in solutions of disodium tetraborate, disodium octaborate and buffered solutions of boric acid and boric oxide (Ingri N (1963)).
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.