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Physical & Chemical properties

Melting point / freezing point

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Reference
Endpoint:
melting point/freezing point
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Justification for type of information:
All members of the category ‘Lithium salts of the oxyacids of boron (B)’ are formed in situ and are immediately formulated into grease thickeners which are marketed and used within the EU/EEA. Dilithium tetraborate is the only member to be manufactured and isolated in an available form for testing. All other members are not isolated and would require extraction from the grease thickener products for testing to be conducted on the isolated substance itself. As testing requires a substantial quantity of material, it was decided to perform the testing on the only isolated product, dilithium tetraborate for this category approach.

All of the substances in this category are inorganic lithium salts of boric acid and are solid at ambient temperature and are expected to have similar high melting points of >500 °C. The melting point of dilithium tetraborate was reported as >500 °C, while the CRC Handbook reports the melting point of lithium metaborate as 849°C. Any variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in the melting point. A result of >500 °C is therefore expected for lithium tetrahydroxyborate; read-across to the data for dilithium tetraborate is therefore proposed.
Melting / freezing pt.:
> 500 °C
Conclusions:
The melting point of lithium tetrahydroxyborate is expected to be >500 °C.
Executive summary:

The melting point of dilithium tetraborate was determined to be >500 °C in an OECD 102. As lithium tetrahydroxyborate is also an inorganic borate substance it is expected to have a similar high melting point of >500 °C. A high melting point is consistent with the data reported in the CRC handbook for lithium metaborate (849 °C).

Description of key information

The melting point of dilithium tetraborate was determined to be >500 °C in an OECD 102. As lithium tetrahydroxyborate is also an inorganic borate substance it is expected to have a similar high melting point of >500 °C. A high melting point is consistent with the data reported in the CRC handbook for lithium metaborate (849 °C).

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
500 °C

Additional information