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=2.94×109s−1mol−1L), 2,5-dimethyl-2,4-hexadiene (kqP=1.91×109s−1mol−1L), 2,4-dimethyl-1,3-pentadiene (kqP=1.78×108s−1mol−1L), 3-methyl-1,3-pentadiene (kqP=1.22×108s−1mol−1L), 2,4-hexadiene (kqP=1.35×108s−1mol−1L) and trans-2-methyl-1,3-pentadiene (kqP=3.84×108s−1mol−1L). Cyclooctene also quenched biacetyl phosphorescence but with a lower rate (kqP=1.97×107s−1mol−1L). 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.