Paracetamol

Endpoint summary

Additional information

Appearance/physical state/colour

On the basis of experimental results Paracetamol was found to be a White powder organic solid.

Melting point/freezing point

The melting point determination of Paracetamol (CAS No.103-90-2) was done following OECD Guideline 102 and according to the Capillary/metal block method. The test was conducted in replicates and mean melting point range was found to be 165.6 °C - 168°C at 980.4hPa.

Boiling point

The boiling point determination of Paracetamol (CAS No. 103-90-2 ) was done following OECD Guideline 103 and according to the method of Siwoloboff. The test was conducted in replicates and mean boiling point was found to be greater than 250 °C at 980.1 hPa.

Density

The density of test item Paracetamol (CAS No. 103-90-2 )was determined following OECD Guideline 109 and according to the method Adapted from ASTM D854-02 using glass pyknometer .The mean density of the test item was found to be 1.214 g/cm3 at 20 °C and 977.1.hPa.

Particle size distribution (Granulometry)

The particle size distribution of test itemParacetamol (CAS No. 103-90-2)was determined by granulometric analysis with rotap sieve shaker. The cumulative percentages of test item obtained for each sieve are as follows:

                                                                                                              

Sieve sizes(in microns)	Percentage distribution (%) of test item
150 microns	23.52%
106 microns	36.02 %
75 microns	34.44%
53 microns	3.88%
25 microns	0.14%
10 microns	-------

Vapour pressure

The vapour pressure of paracetamol was found to be 0.008385954 Pa at 25 degC.

Partition coefficient

The experimental value of octanol water partition co-efficient (log Pow) of paracetamol is 0.46 at temperature 25 degC.This value indicates that paracetamol is hydrophilic in nature.

Water solubility

The water solubility determination of test item Paracetamol (CAS No. 103-90-2) was done gravimetrically as per the shake flask method using membrane filtration followed by air drying. The water solubility was found to be 19 g/L at 28 deg.C.

Solubility in organic solvents / fat solubility

Gravimetric method was used to determine the solubility of the substance in organic solvent.The experimental value of solubility of paracetamol in ethanol at 26 degC was found to be 3000 mg/L indicating that this substance is soluble in ethanol.Using the Soxhlet/Solvent extraction method the solubility of the substance in Petroleum ether is observed to be 40 mg/L at 26 degC indicating that the substance is slightly soluble in Petroleum ether.The solubility value of paracetamol in ethanol at 20 degC is equivalent to a value of 2307.69 mg/L.

Surface tension

Paracetamol is a solid chemical. In order to calculate surface tension it shall have to be dissolved either in water or an organic solvent. In this case, there is every likelyhood that the surface tension that shall be calculated of the solution of paracetamol might actually erroneously reflect the measurement of surface tension of the solvent (either water or organic solvent). Hence this end point was considered for waiver considering the technical difficulty in surface tension measurement of solid paracetamol.

Flash point

The flash point determination of Paracetamol (CAS No. 103-90-2) was done following closed cup method using Pensky-Martens flash point apparatus. The test was conducted in replicates and mean flash point was found to be 184.6 °C at 979.9 hPa.

Auto flammability

Paracetamol did not catch fire on being exposed to air at room temperature of 26 degC and atmospheric pressure of 966 hPa. This indicates that paracetamol is not auto-flammable.

Flammability

From the experimental values of flammability, paracetamol ignited when the flame of bunsen burner having temperature of 950 degC was brought in contact with it. Thus it can be concluded that paracetamol is flammable only at high temperature of about 950 degC. However since such high temperatures are not found under normal circumstances of transportation and use, paracetamol was considered non-flammable for chemical safety assessment.

Explosiveness

According to theoretical considerations based on chemical structure, paracetamol does not possess explosive properties. The reason for this is there are no chemical groups associated with explosive properties in paracetamol. Thus, as per column 2 of Annex VII this end point was considered for waiver.

Oxidising properties

Paracetamol was found to have mild oxidising property since 284.4 ml of KMnO4 was required for getting the end point of the redox titration for 100 g of paracetamol.This oxidation potential was not considered strong enough for classifying the chemical as an oxidising solid.Thus, the chemical is considered as non-oxidising for the purpose of chemical safety report and classification.

Stability in organic solvents and identity of relevant degradation products

Paracetamol was found to be stable in organic solvent dichloro methane and no degradation products were formed after 24 hours as evident from the GC-MS chromatogram obtained at 0 hours and that obtained after 24 hours.

pH

The pH determination of test item Paracetamol (CAS No. 103-90-2) was done following OECD guideline 122. pH of 1% w/v aqueous solution was measured with the help of pH meter and it was observed to be 5.82 at 30°C

Dissociation constant

The experimental pKa value for paracetamol was found to be 0.000000523 at 26 degC indicating that it has dissociation properties.This value when converted at 20 deg C is equivalent to 0.000000402.

Viscosity

This end point was considered for waiver since viscosity is an inherent property of a liquid that offers resistance to its flow and paracetamol is a solid substance and hence this testing was considered scientifically unjustified for paracetamol.