The dimerization of butadiene by palladium complex catalysts

Abstract

It has been found that palladium-phosphine complexes coordinated by dienophile and tetrakis-(triphenylphosphine) palladium catalyzed the linear dimerization of butadiene. The dimerization of butadiene with bis(triphenylphosphine)(maleic anhydride)palladium in aprotic solvents, such as benzene, tetrahydrofuran, and acetone, gave octatriene-1,3,7 selectively in good yields. In such alcohols as methanol, ethanol, and isopropanol, butadiene was converted to 1-alkoxyoctadiene-2,7 and/or octatriene-1,3,7, depending on the nature of the alcohols employed. The dimerization in secondary amines, such as morpholine, piperidine, and diisopropylamine, gave butadiene dimer-amine adducts of the R2N(C8H13) type, while that in primary amines, such as aniline and n-butylamine, gave a mixture of RNH(C8H13) and RN(C8H13)2. Phenoxy- and acetoxyoctadiene were also obtained from the reactions in phenol and acetic acid respectively.