Calcium didocosanoate

Endpoint summary

Additional information

Where testing has been conducted to generate data in order to complete physico-chemical endpoints, testing of calcium myristate (C14), at the lower end of the category, calcium 12-hydroxystearate (C18), as a hydroxylated member, and calcium behenate (C22), at the upper end of the category of the category, was considered the most efficient approach. The data for the longest and shortest carbon chain lengths and for a hydroxylated substance in the middle of the category were generated to bracket the possible range of properties across the category and to show that substance properties are consistent across the range of carbon chain lengths. The testing of three substances at strategic points in the category is designed to ensure that the most conservative results are identified and, where appropriate, provide a classification which covers all of the substances in the category.

Appearance/physical state/colour

All of the substances in the calcium salts of monocarboxylic acids C14-C22 category are solids at room temperature.

Calcium myristate is a white solid at ambient temperature. The data are taken from substance identification information in a GLP-compliant, guideline study available as an unpublished report (Harlan 2013).

Calcium palmitate is a solid at ambient temperature. The data are taken from a published handbook (Lide 2009). The introduction to the CRC Handbook of Chemistry and Physics (Lide 2009) states that data for physical constants have been taken from many sources, including both compilations and the primary literature. Where conflicts were found, the value deemed the most reliable was chosen. Therefore, although the methods used are not known, the values presented here are acceptable as they are from a reliable secondary source of physico-chemical data.

Calcium oleate is a white-yellow solid at ambient temperature. The data are taken from a peer-reviewed handbook (O’Neil 2006).

The introduction to the Merck Index (O’Neil 2006) states that physical data are cited as found in the literature. When several alternate data values appear in the literature, the data are evaluated and representative selections are made; values are then reported with the corresponding source. Therefore, although the methods used are not known, the values presented here are acceptable as they are from a reliable secondary source of physico-chemical data.

Calcium stearate is a solid at ambient temperature. The data are taken from the substance identity information provided in a proprietary ecotoxicity study (TUV Bayern 1992). Data are also taken from published regulatory documents (Criteria group for Swedish occupational standards 1994, ICPS 1994) and published, peer-reviewed handbooks and review articles (O’Neil 2006, Lide 2009, CIR 1982). The preface to the scientific basis for Swedish occupational standards (1994) states that several databases are used when conducting literature searches (e.g. RTECS, Toxline, Medline, Cancerlit, Nioshtic and Riskline) along with previous regulatory documents (e.g. WHO, EU, US NIOSH, the Dutch Expert Committee for Occupational Standards (DECOS) and the Nordic Expert Group) and sometimes handbooks. All relevant published data undergo a qualified evaluation and in some cases, if criteria are not fulfilled, the information will be omitted or included with an explanation. A draft consensus of this information is written, discussed and approved by the Criteria group. The International Chemical Safety Cards (IPCS 1994) are produced by the World Health Organisation’s (WHO) International Programme on Chemical Safety (IPCS). The introduction to the ICSC states that they report “information collected, verified and peer-reviewed by internationally recognised scientists”. Therefore, although the methods used are not known, the values presented here are acceptable as they are from reliable secondary sources of physico-chemical data.

Calcium 12 -hydroxystearate is a white solid at ambient temperature. The data are taken from substance identification information in a GLP-compliant, guideline study available as an unpublished report (Harlan 2013).

Calcium behenate is a white solid at ambient temperature. The data are taken from substance identification information in a GLP-compliant, guideline study available as an unpublished report (Harlan 2013).

Calcium myristate, the shortest carbon chain length substance in the category, calcium palmitate, calcium oleate, calcium stearate and calcium 12-hydroxysterate, with intermediate carbon chain lengths, and calcium behenate, the longest carbon chain length substance in the category, are all solids at room temperature. As these substances are all solids at room temperature, it can be justifiably expected that the remaining substances in the category are solids as well.

Melting point/freezing point

All of the substances in the calcium salts of monocarboxylic acids C14-C22 category have melting points in the range of approximately 120 to 180°C.

The melting point of calcium myristate is approximately 120 to 166°C. The melting point of calcium myristate was determined in a GLP-compliant thermal analysis test, following OECD guideline 102 (Harlan 2013).

The melting point of calcium stearate is approximately 129 to 180°C. The melting point of calcium stearate was taken from published regulatory documents (Criteria group for Swedish occupational standards 1994, ICPS 1994) and published, peer-reviewed handbooks and review articles (O’Neil 2006, Lide 2009, CIR 1982).

The melting point of calcium 12 -hydroxystearate is approximately 136 to 158°C. The melting point of calcium 12 -hydroxystearate was determined in a GLP-compliant thermal analysis test, following OECD guideline 102 (Harlan 2013).

The melting point of calcium behenate is approximately 140 to 158°C. The melting point of calcium behenate was determined in a GLP-compliant thermal analysis test, following OECD guideline 102 (Harlan 2013).

The melting point of calcium myristate, the shortest carbon chain length substance in the category, is approximately 120 to 166°C. The melting point of calcium stearate, with an intermediate chain length, is approximately 129 to 180°C. The melting point of calcium 12–hydroxystearate, with an intermediate chain length, is approximately 136 to 158°C. The melting point of calcium behenate, the longest carbon chain length substance in the category, is approximately 140 to 158°C. The data for the end members of the category and substances with intervening carbon chain lengths all have similar melting points in the range of 120 to 180°C. It can be justifiably expected that the melting points of remaining substances in the category with intervening carbon chain lengths would have similar melting points within this range and therefore can be read across from the available data. All of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to have melting points in the range of 120 to 180°C.

Boiling point

All of the substances in the calcium salts of monocarboxylic acids C14-C22 category decompose before boiling to give a solid residue. The boiling point test is therefore not technically feasible on these substances.

No determination of the boiling temperature was feasible for calcium myristate, calcium 12-hydroxystearate or calcium behenate as they were determined to decompose before boiling (Harlan 2013).

The decomposition temperature of calcium myristate is approximately 170°C. The decomposition temperature of calcium myristate was determined in a GLP-compliant thermal analysis test, following OECD guideline 102 (Harlan 2013).

The decomposition temperature of calcium palmitate is approximately 155°C. The decomposition temperature of calcium palmitate was taken from a peer-reviewed handbook (Lide 2009, O’Neil 2006).

The decomposition temperature of calcium oleate is >140°C based on data taken from a peer-reviewed handbook (O’Neil 2006).

The decomposition temperature of calcium 12 -hydroxystearate is approximately 246°C. The decomposition temperature of calcium 12 -hydroxystearate was determined in a GLP-compliant thermal analysis test, following OECD guideline 102 (Harlan 2013).

The decomposition temperature of calcium behenate is approximately 165°C. The decomposition temperature of calcium behenate was determined in a GLP-compliant thermal analysis test, following OECD guideline 102 (Harlan 2013).

The decomposition temperature of calcium myristate, the shortest carbon chain length substance in the category, is approximately 170°C. The decomposition temperature of substances with intermediate chain lengths is approximately 155°C for calcium palmitate, >140°C for calcium oleate and approximately 246°C for calcium 12–hydroxystearate. The decomposition temperature of calcium behenate, the longest carbon chain length substance in the category, is approximately 165°C. The data for the end members of the category and substances with intervening carbon chain lengths all have similar decomposition temperatures. It can be justifiably expected that the decomposition temperatures of remaining substances in the category would decompose before boiling, with similar decomposition temperatures in the range of 140 to 246°C and therefore can be read across from the available data. All of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to decompose before boiling, with decomposition temperatures in the range of 140 to 246°C.

Density

All of the substances in the calcium salts of monocarboxylic acids C14-C22 category have similar relative densities of just above 1, in the range of 1.08 to 1.12 at 20°C.

The relative density of calcium myristate is 1.08 at 20°C. The relative density of calcium myristate was determined in a GLP-compliant pycnometer test following OECD guideline 109 (Harlan 2013).

The density of calcium stearate of 1.12 g/cm³ is taken from a published regulatory document (IPCS 1994).

The relative density of calcium 12 -hydroxystearate is 1.08 at 20°C. The relative density of calcium 12 -hydroxystearate was determined in a GLP-compliant pycnometer test following OECD guideline 109 (Harlan 2013).

The relative density of calcium behenate is 1.10 at 20°C. The relative density of calcium behenate was determined in a GLP-compliant pycnometer test following OECD guideline 109 (Harlan 2013).

The relative densities of calcium myristate, calcium stearate, calcium 12-hydroxystearate and calcium behenate are all the very similar, at 1.08 to 1.12. As all of these substances show the very similar densities, it can be justifiably expected that the densities of the remaining substances in the category would have similar relative density values as well. All of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to have similar relative densities of just above 1, in the range of 1.08 to 1.12 at 20°C.

Vapour pressure

The vapour pressure could not be determined for any of the substances in the calcium salts of monocarboxylic acids C14-C22 category. The vapour pressure test is not technically feasible for these substances as the predicted vapour pressures were below the limit of detection of the test methods. Standard test methods, according to OECD guideline 104, are able to measure vapour pressure from 10 E-10 Pa to 10 E+05 Pa. As the predicted vapour pressures for the substances in the calcium salts of monocarboxylic acids C14-C22 category are below 10 E-10 Pa, the vapour pressures tests were not conducted.

No determination of the vapour pressure is feasible for calcium myristate as the predicted vapour pressure is below the limit of detection of the test methods. Using the Modified Grain Method in EPISuite (MPBVP v1.43, US EPA 2009), calcium myristate has a predicted vapour pressure of 3.91 E-10 Pa, calcium palmitate has a predicted vapour pressure of 1.02 E-11 Pa, calcium oleate has a predicted vapour pressure of 1.73 E-13 Pa, calcium stearate has a predicted vapour pressure of 6 E-12 Pa, calcium 12-hydroxystearate has a predicted vapour pressure of 1.46 E-19 Pa and calcium behenate has a predicted vapour pressure of 2.67 E-16 Pa.

The vapour pressures of calcium myristate, calcium 12-hydroxystearate and calcium behenate were not determined as they all predicted to be below the limit of detection of the test methods. As the tests could not be conducted on the substances with the longest and shortest carbon chain length in the category, as well as intermediary substances, it is considered justified to expect that the remaining substances in the category with intervening carbon chain lengths would have similarly low vapour pressures and therefore cannot be tested. As the predicted vapour pressures for the substances in the calcium salts of monocarboxylic acids C14-C22 category are below 10 E-10 Pa, the vapour pressures tests were not conducted.

Water solubility

The water solubilities of the calcium salts of monocarboxylic acids C14-C22 category were determined to be in the range of 0.15 to 3.07 mg/L.

The water solubility of calcium myristate was determined to be 0.821 mg/L based on the monitoring of free myristic acid (calculated as equivalent calcium myristate) and 0.415 mg/L based on the total dissolved calcium concentration of the sample solutions. The water solubility of calcium myristate was determined in a GLP-compliant test following EU method A6 (Harlan 2013).

The water solubility of calcium stearate is reported as 2.2 mg/L at 20°C in an unpublished proprietary study (TUV Bayern 1992) following OECD guideline 105. Only a summary of the study is available and there is limited information on the test methods and conditions used.

The water solubility of calcium 12-hydroxystearate was determined to be 2.12 to 3.07 mg/L based on the monitoring of free 12-hydroxystearic acid (calculated as equivalent calcium 12-hydroxystearate) and 0.48 to 0.74 mg/L based on the total dissolved calcium concentration of the sample solutions. The water solubility of calcium 12-hydroxystearate was determined in a GLP-compliant test following EU method A6 (Harlan 2013).

The water solubility of calcium behenate was determined to be 0.15 mg/L based on the monitoring of free behenic acid (calculated as equivalent calcium behenate) and 0.88 mg/L based on the total dissolved calcium concentration of the sample solutions. The water solubility of calcium behenate was determined in a GLP-compliant test following EU method A6 (Harlan 2013).

The water solubility of calcium myristate was determined to be 0.821 mg/L based on the monitoring of free myristic acid (calculated as equivalent calcium myristate) and 0.415 mg/L based on the total dissolved calcium concentration of the sample solutions. The water solubility of calcium 12-hydroxystearate was determined to be 2.12 to 3.07 mg/L based on the monitoring of free 12-hydroxystearic acid (calculated as equivalent calcium 12-hydroxystearate) and 0.48 to 0.74 mg/L based on the total dissolved calcium concentration of the sample solutions. The water solubility of calcium behenate was determined to be 0.15 mg/L based on the monitoring of free behenic acid (calculated as equivalent calcium behenate) and 0.88 mg/L based on the total dissolved calcium concentration of the sample solutions. The data indicate that water solubility for the longest, shortest and an intermediate carbon chain length are all very similar and thus, it can be justifiably expected that water solubilities of remaining substances in the category with intervening carbon chain lengths can be read across from the available data. All of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to have water solubilities in the range of 0.15 to 3.07 mg/L at 20°C.

Partition Coefficient

The partition coefficient could not be determined for any of the substances in the calcium salts of monocarboxylic acids C14-C22 category. The partition coefficient tests are not technically feasible on these substances. No determination was carried out using the shake-flask method or HPLC estimation method as calcium myristate, calcium 12-hydroxystearate and calcium behenate were insufficiently soluble in n-octanol and water which prevented the use of the shake-flask method and the HPLC method is not suitable for salts of organic acids.

The water solubilities of calcium myristate, calcium 12-hydroxystearate and calcium behenate, along with the preliminary results on octanol solubility, were taken from proprietary study reports (Harlan 2013). The solubility of calcium myristate in n-octanol was determined visually to be less than 5 mg/L. The water solubility was determined analytically to be 0.821 mg/L of solution at 20°C, when monitoring the free myristic acid (calculated as equivalent calcium myristate). The solubility of calcium 12-hydroxystearate in n-octanol was determined visually to be less than 6 mg/L. The water solubility was determined to be in the range 2.12 to 3.07 mg/L of solution at 20°C, when monitoring free 12-hydroxystearic acid (calculated as equivalent calcium 12-hydroxystearate). The solubility of calcium behenate in n-octanol was determined visually to be less than 5 mg/L. The water solubility was determined to be less than 0.15 mg/L of solution at 20°C, when monitoring free behenic acid (calculated as equivalent calcium behenate).

The partition coefficients were estimated by QSAR but the results are considered not to be relevant to the substances themselves. As the calcium salts of monocarboxylic acids C14-C22 are ionisable salts, the partition coefficient can vary greatly depending on pH and the pKa of the substance.  In order to compare partition coefficient values of different, ionisable compounds on a relative basis, partition coefficient values are sometimes reported as "corrected for ionisation", indicating that the value represents the partition coefficient at a pH where a compound exists primarily in the non-ionised form.

The calcium salts of fatty acids in this category are typically not synthesised as the “pure” compounds and seldom exist except in the presence of the oil matrix. High temperature stability indicates that the grease thickener structure is robust and resistant to diffusion out of the oil. Dissolution of grease thickeners from grease into water is very unlikely as the thickeners are poorly water soluble and the thickeners are embedded in the hydrophobic grease matrix and therefore less likely to leach out. Thus the partition coefficient of the substances is not expected to be relevant.

The partition coefficients of calcium myristate, calcium 12-hydroxystearate and calcium behenate could not be determined as they have insufficient solubility in octanol. As the tests could not be conducted on the substances with the longest and shortest carbon chain length in the category, as well as an intermediary substance, it is considered justified to expect that the remaining substances in the category with intervening carbon chain lengths would behave in the same manner and therefore cannot be tested for partition coefficient.

Surface tension

As the cut-off for being considered surface active is 60 mN/m and calcium myristate, calcium 12-hydroxystearate and calcium behenate all exceed this, the category members with intervening carbon chain lengths are not expected to have surface active properties.

The surface tension of a 90 % saturated solution of calcium myristate is 69.4 to 70.4 mN/m at 21°C. The surface tension of a 90 % saturated solution of calcium 12 -hydroxystearate is 66.0 to 68.2 mN/m at 21°C. The surface tension of a 90 % saturated solution of calcium behenate is 70.1 to 71.4 mN/m at 21.0°C.

The surface tension of calcium myristate, calcium 12 -hydroxystearate and calcium behenate were conducted in GLP-compliant ring balance tests following OECD guideline 115 (Harlan 2013). The studies deviated from the guideline because the ring apparatus had a smaller diameter than recommended in the guideline. The deviation was not considered to have affected the integrity of the studies. Calcium myristate, calcium 12 -hydroxystearate and calcium behenate have surface tensions above 60 mN/m and therefore do not meet the criteria for being surface active.

The surface tension of a 90 % saturated solution of calcium myristate, the shortest carbon chain length substance in the category, is 69.4 to 70.4 mN/m at 21°C. The surface tension of a 90 % saturated solution of calcium 12 -hydroxystearate, with an intermediate chain length, is 66.0 to 68.2 mN/m at 21°C. The surface tension of a 90 % saturated solution of calcium behenate, the longest carbon chain length substance in the category, is 70.1 to 71.4 mN/m at 21.0°C. The surface activities of all of the tested substances are very similar and it can be justifiably expected that the remaining substances in the category with intervening carbon chain lengths would have similar surface tensions, in the range of 66.0 to 71.4 mN/m at 21°C. As the boundary for surface activity properties is 60 mN/m, the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered not to be surface active.

Auto-flammability

All of the substances in the calcium salts of monocarboxylic acids C14-C22 category have self-ignition temperatures above their melting points. Therefore none of the substances in the category meet the criteria for classification as a self-heating substance.

Calcium myristate was determined not to have a relative self-ignition temperature below its melting point (i.e. greater than approximately 166°C). Calcium 12 -hydroxystearate was determined not to have a relative self-ignition temperature below its melting point (i.e. greater than approximately 158°C). Calcium behenate was determined not to have a relative self-ignition temperature below its melting point (i.e. greater than approximately 158°C). The relative self-ignition temperature of calcium myristate, calcium 12 -hydroxystearate and calcium behenate were tested in GLP-compliant studies following EC 440/2008 A16 method (Harlan 2013).

The self-ignition temperatures of calcium myristate, calcium 12-hydroxystearate and calcium behenate are all above their melting points. As the self-ignition temperatures of the substances with the longest and shortest carbon chain lengths in the category, as well as one with an intermediary chain length, are above their respective melting points, it is considered justified to expect that the remaining substances in the category with intervening carbon chain lengths would also have self-ignition temperatures above their respective melting points. Therefore none of the substances in the category meet the criteria for classification as a self-heating substance.

Flammability

None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to be highly flammable. Therefore none of the substances in the category meet the criteria for classification as flammable solids.

Calcium myristate, calcium 12 -hydroxystearate and calcium behenate have been determined to be not highly flammable as they failed to ignite in the preliminary screening tests. The flammability of calcium myristate, calcium 12 -hydroxystearate and calcium behenate were tested in a GLP-compliant test following the method EC440/2008 A10 (Harlan 2013).

Calcium myristate, calcium 12-hydroxystearate and calcium behenate are not considered to be flammable as they all failed to ignite in the preliminary screening test. As the substances with the longest and shortest carbon chain lengths in the category, as well an intermediary substance, are not highly flammable, it is considered justified to expect that the remaining substances in the category with intervening carbon chain lengths would not be highly flammable either. None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are considered to be highly flammable and therefore none of the substances in the category meet the criteria for classification as flammable solids.

Experience in manufacture and handling shows that the substances in the calcium salts of monocarboxylic acids C14-C22 category do not ignite spontaneously on coming into contact with air at normal temperatures and are stable at room temperature for prolonged periods of time (days). Experience has also shown that the substances do not react with water and therefore they do not meet the criteria for classification as pyrophoric substances or substance which on contact with water emit flammable gases.

Other physico-chemical endpoints

As the calcium salts of monocarboxylic acids C14-C22 are solids, the viscosity and flash point endpoints are not required. Based on the structure of the substances in this category, the explosiveness and oxidising properties studies have not been conducted as there are no structural alerts that would indicate explosive or oxidising properties. The stability in organic solvents and identity of relevant degradation products study has not been conducted as they are not considered to be critical endpoints. As the substances are manufactured and used in situ in a base oil, the substances are not marketed or used in isolated solid or granular forms and so the particle size distribution test has been waived.

Classification and labelling

None of the substances in the calcium salts of monocarboxylic acids C14-C22 category are classified for physico-chemical hazards under the CLP. Based on the structure of the substances, they do not meet the criteria for oxidising or explosive and based on experimental data, the substances do not meet the criteria for flammable solids or self-heating substances.

References

Klimisch HJ, Andreae M, Tillmann U (1997) A systematic approach for evaluating the quality of experimental toxicological and ecotoxicological data. Regulatory toxicology and pharmacology, vol. 25, pp. 1-5