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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:

The UVCB - Reaction products of boric acid and calcium dihydroxide and lithium hydroxide (EC # 701-453-3) has structural similarities to two already established categories: lithium salts of the oxyacids of boron (B); and calcium salts of the oxyacids of boron (B). Dilithium tetraborate (EC# 234-514-3) (source substance #1) and calcium metaborate (EC# 237-224-5) (source substance #2) will be used to predict the properties for the target substance.
The target UVCB substance is made up of components from both categories and is manufactured by mixing calcium hydroxide, lithium hydroxide and boric acid in an oil medium in such a ratio that they react to form a complex mixture of lithium calcium borates as components of a colloidal mixture which is subsequently used as a lubricating grease.

All of the substances in these two categories are inorganic lithium salts/calcium salts of boric acid and are solid at ambient temperature and are expected to have similar physiochemical properties.
All lithium/calcium borate substances are expected to be soluble in water and should exhibit essentially the same water solubility value since, in a water environment, all lithium/calcium borate salts will exist in equilibrium with boric acid.
Variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in the water solubility.
The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.
An experimental study on dilithium tetraborate provided a water solubility value of 141.2 g/L which indicates that the substance is very soluble in water. This result is consistent with the data reported in the CRC Handbook for lithium metaborate which states that the substance is very soluble in water. It is expected that Reaction products of boric acid and calcium dihydroxide and lithium hydroxide will also be equally as soluble. Read-across to the result for dilithium tetraborate is therefore proposed for the REACH registration of Reaction products of boric acid and calcium dihydroxide and lithium hydroxide.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Key result
Water solubility:
141.2 g/L
Conc. based on:
test mat.
Temp.:
20 °C
pH:
>= 9.35 - <= 9.44
Conclusions:

Reaction products of boric acid and calcium dihydroxide and lithium hydroxide is expected to be very soluble in water and have a solubility of around 141.2 g/L.
Executive summary:

All lithium/calcium borate substances are expected to be soluble in water and should exhibit essentially the same water solubility value since, in a water environment, all lithium/calcium borate salts will exist in equilibrium with boric acid. In an experimental study, dilithium tetraborate was found to have a water solubility value of 141.2 g/L which indicates that the substance is very soluble in water.


The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.


Read-across to the result for dilithium tetraborate is therefore proposed for this endpoint. A value of 141.2 g/L will also be reported for Reaction products of boric acid and calcium dihydroxide and lithium hydroxide since any variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in the water solubility.  

Description of key information

All lithium/calcium borate substances are expected to be soluble in water and should exhibit essentially the same water solubility value since, in a water environment, all lithium/calcium borate salts will exist in equilibrium with boric acid. In an experimental study, dilithium tetraborate was found to have a water solubility value of 141.2 g/L which indicates that the substance is very soluble in water.


The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.


Read-across to the result for dilithium tetraborate is therefore proposed for this endpoint. A value of 141.2 g/L will also be reported for Reaction products of boric acid and calcium dihydroxide and lithium hydroxide since any variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in the water solubility.  

Key value for chemical safety assessment

Water solubility:
141.2 g/L
at the temperature of:
20 °C

Additional information