Reaction products of boric acid and calcium dihydroxide and lithium hydroxide

Auto flammability

Link to relevant study record(s)

Reference

Endpoint:

relative self-ignition temperature (solids)

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.
A self-heating substance as follows: a solid or liquid substance or mixture, by reaction with air and without energy supply, is liable to self-heat; this substance or mixture differs from a pyrophoric liquid or solid in that it will ignite only when in large amounts (kilograms) and after long periods of time (hours or days).

The self-heating potential of substances is based on chemical structure and susceptibility of molecular bonds to oxidation. All of the substances in these two categories are inorganic lithium salts/calcium salts of boric acid and do not have any molecular bonds which are susceptible to oxidation. In addition, they have a similar chemical composition where any variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in their self-heating potential. 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.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Remarks on result:

other: No self-ignition temperature noted.

Remarks:

Negative outcome (no effect observed)

Conclusions:

It can be concluded that
Reaction products of boric acid and calcium dihydroxide and lithium hydroxide is not a self-heating solid and therefore not subject to transportation restrictions of UN Class 4 Division 4.2.

Executive summary:

For solids, self-heating may occur by reaction with air with subsequent ignition. According to the CLP Regulation, Annex I, section 2.11, a self heating substance or mixture is a liquid or solid substance or mixture, other than a pyrophoric liquid or solid, which, by reaction with air and without energy supply, is liable to self-heat. Therefore the self ignition temperature of solids are considered under self heating and as a result, the UN Test N.4 is preferable for solids to generate information for this endpoint

 

Under the conditions of UN Test N.4, the results excluded dilithium tetraborate and calcium metaborate as a self-heating solid. Self-heating properties are based on chemical structure and susceptibility of molecular bonds to oxidation.  Reaction products of boric acid and calcium dihydroxide and lithium hydroxide has a similar chemical structure to these substances; any variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in their self-heating potential.  It can therefore be concluded that Reaction products of boric acid and calcium dihydroxide and lithium hydroxide is not a self-heating solid and therefore not subject to transportation restrictions of UN Class 4 Division 4.2.

Description of key information

 Reaction products of boric acid and calcium dihydroxide and lithium hydroxide has a similar chemical structure to these substances; any variations due to the range of trigonal and tetrahedral species between the substances are not expected to lead to any changes in their self-heating potential.  It can therefore be concluded that Reaction products of boric acid and calcium dihydroxide and lithium hydroxide is not a self-heating solid.