Determination of the Bromine Number in Petroleum Products and Aliphatic Olefins According to ASTM D1159

The bromine number is a key parameter when it comes to determining aliphatic C=C double bonds in petroleum products. The determination of the bromine number is typically carried out with electrochemical titration at 5 °C, with the bromine being generated in situ from a bromide/bromate solution.

To achieve the titration, a mixture of solvents comprising glacial acetic acid, methanol, and chloroform is usually used. For the experiment performed in this Application Note, the toxic chloroform was replaced with diethyl carbonate.



Transformer oil spiked with 6.6 g/L cyclohexene

Sample Preparation

Based on the expected bromine number a known amount of sample is weighed out and dissolved in 50 mL diethyl carbonate.



The blank is determined using an identical technique as for the sample but using diethyl carbonate instead of the sample.


Following the pipetting of 110 mL titration solvent and 5 mL sample solution into a titration vessel, it is stirred while it is cooled down to 0–5 °C. The solution is then titrated with c(Br2) = 0.25 mol/L until after the equivalence point.





This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.

For more information on this source, please visit Metrohm AG.

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