ASTM D1159 Standard Test Method for Bromine Numbers of Petroleum Distillates and Commercial Aliphatic Olefins by Electrometric Titration
8. Check Procedure
8.1 In case of doubt in applying the procedure to actual samples, the reagents and techniques can be checked by means of determinations on freshly purified cyclohexene or diisobutene. (Warning - The user of this test method may choose to use either 1,1,1-trichloroethane or dichloromethane to the exclusion of the other solvent. The selected solvent is to be used for all operations, that is, in the preparation of the titration solvent, for the dilution of samples, and as the titration blank.) Proceed in accordance with Section 9, using a sample of either 0.6 to 1 g freshly purified cyclohexene or diisobutene (see Table 1) or 6 to 10 g of 10 mass percent solutions of these materials in 1,1,1-trichlorethane. (Warning - Flammable.)
8.2 If the reagents and techniques are correct, values within the following should be obtained:
The reference olefins yielding the above results are characterized by the properties shown in Table 1. The theoretical bromine numbers of cyclohexene and diisobutene are 194.6 and 142.4, respectively.
8.3 Purified samples of cyclohexene and diisobutene can be prepared from cyclohexene and diisobutene, by the following procedure:
8.3.1 Add 65 g of activated silica gel, 75 to 150 µm (100 to 200 mesh) manufactured to ensure minimum olefin polymerization to a column approximately 16 mm in inside diameter and 760 mm in length, that has been tapered at the lower end and that contains a small plug of glass wool at the bottom. A100-mL buret, or any column that will give a height-to-diameter ratio of the silica gel of at least 30:1, will be suitable. Tap the column during the adding of the gel to permit uniform packing.
8.3.2 To the column add 30 mL of the olefin to be purified. When the olefin disappears into the gel, fill the column with methanol. Discard the first 10 mL of percolate and collect the next 10 mL that is the purified olefin for test of the bromine number procedure. Determine and record the density and refractive index of the purified samples at 20°C. Discard the remaining percolate. (Warning - If distillation of impure olefins is needed as a pre-purification step, a few pellets of potassium hydroxide should be placed in the distillation flask and at least 10 % residue should remain to minimize the hazards from decomposition of any peroxides that may be present.)