TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred components: The catalyst for catalyzing cyclo-dimerization of isoprene comprises catalyst selected from nickel catalyst, iron catalysts and chromium catalysts. The catalyst for catalyzing partial hydrogenation of isoprene or the chemical capable of partially hydrogenating isoprene in the system (S1) comprises a palladium catalyst. The catalyst for catalyzing dimerization of mono-olefin, or the chemical capable of dimerizing the isoamylene with mono-olefins in the system (S1) comprises an acid catalyst. In the system (S1), the chemical capable of dimerizing isoprene comprises catalyst for catalyzing cyclo-dimerization of isoprene comprises catalyst selected from ruthenium catalysts, nickel catalysts, iron catalysts and chromium catalysts. The catalyst in the system (S1) for hydrogenating the unsaturated isoprene dimmers comprises a catalyst selected from palladium catalysts, nickel catalysts, ruthenium catalysts and rhodium catalysts.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In the method (M1), at least 95% of isoprene in the bioisoprene composition is converted to non-isoprene compounds. In the method (M1), bioisoprene composition is heated to 150-250 degrees C to produce an unsaturated cyclic isoprene dimer and the unsaturated cyclic isoprene dimer is hydrogenated catalytically to produce saturated cyclic isoprene dimer fuel constituent. The method (M1) involves contacting the bioisoprene composition with catalyst for catalyzing cyclo-dimerization of isoprene to produce an unsaturated cyclic isoprene dimer and the unsaturated cyclic isoprene dimer is hydrogenated catalytically to produce saturated cyclic isoprene dimer fuel constituent. In the method (M1), the step of partially hydrogenating the bioisoprene composition involves contacting the bioisoprene composition with hydrogen gas and a catalyst for catalyzing partial hydrogenation of isoprene. In the method (M1), the step of dimerizing the isoamylene with a mono-olefin involves contacting the isoamylene with the mono-olefin in the presence of a catalyst for catalyzing dimerization of mono-olefin. The method (M1) further involves purifying the isoprene from the bioisoprene composition prior to chemically transforming the bioisoprene composition to a fuel constituent. Preferred Composition: The bioisoprene composition in the system (S1) comprises greater than 2 mg of isoprene and comprises greater than or equal to 99.94 wt.% isoprene compared to the total weight of all 5C hydrocarbons in the composition. The fuel composition (C1) is free of isoprene. The fuel composition (C1) has delta 13C value of greater than -22% or -32% to -24%. EXAMPLE - No suitable example given.