A new fast methodology to measure total diene content in gasoline

The rate constants for the quenching of biacetyl phosphorescence by a series of conjugated dienes were measured. 1,3-cyclohexadiene (kqP = 2.94 × 109 s−1 mol−1 L), 2,5-dimethyl-2,4-hexadiene (kqP = 1.91 × 109 s−1 mol−1 L), 2,4-dimethyl-1,3-pentadiene (kqP = 1.78 × 108 s−1 mol−1 L), 3-methyl-1,3-pentadiene (kqP = 1.22 × 108 s−1 mol−1 L), 2,4-hexadiene (kqP = 1.35 × 108 s−1 mol−1 L) and trans-2-methyl-1,3-pentadiene (kqP = 3.84 × 108 s−1 mol−1 L). Cyclooctene also quenched biacetyl phosphorescence but with a lower rate (kqP = 1.97 × 107 s−1 mol−1 L). Quenching was not observed with 1-methylnaphthalene. Since conjugated dienes quench biacetyl phosphorescence preferentially, this method was studied using gasoline samples with known diene composition. A good correlation was found between the rate of quenching of biacetyl by the gasoline samples and the quantity of conjugated dienes present.