Isoprene → Isoprene butadiene

Participants

Reaction Steps

Eleven hundred milliliters of purified pentane was introduced under a nitrogen atmosphere into a two quart glass-bowled pressure reactor. The reactor was equipped with an air driven stirrer, a pressure gauge, a thermometer well, a heat exchange coil, a top surface inlet valve, a dip tube feeder with a valve, a syringe injection port containing a Viton rubber gasket, and a blow-out disk (200 psi). Five milliliters of a 0.1M dipyridyl in cyclohexane solution was injected into the reactor along with 8.0 mL of anhydrous tetrahydrofuran. Isoprene (18.6 g, 27.3 mL, 0.344 mol), freshly distilled from sodium, was added via syringe to the reaction vessel. The solution was heated to 50° C. and titrated by slow addition of 1.6M n-butyllithium until an orangish color persisted. Then 4.2 mL (6.7 mmol) of n-butyllithium was added. After 4 hr, butadiene (114.7 g, 155 mL, 2.12 mol) was pressured into the same reactor. The solution temperature was maintained at 50°-51° C. for 3 hours. The remainder of the procedure was the same as that described in Example V.

Provenance & Evidence