Development of a Highly Selective and Efficient Catalyst for 1,3-Butadiene Dimerization

Abstract

A selective dimerization reaction of 1,3-butadiene in the presence of 2-propanol to give 1,3,7-octatriene has been developed. By modification of palladium carbene catalysts an unexpected selectivity switch from the telomerization to the dimerization product occurred. In applying the 1,3-bis(2,6-diisopropylphenyl)-4,5-dimethyl-3H-imidazolidenylpalladium(0) complex 9, unprecedented catalyst efficiency (TON > 80 000 and TOF > 5000 h(-1)) has been obtained for this transformation. [reaction: see text]

Development of Palladium–Carbene Catalysts for Telomerization and Dimerization of 1,3‐Dienes: From Basic Research to Industrial Applications

“…With the N-mesitylsubstituted carbene ligand, variation at the 4-and 5-position of the imidazole ring had no effect on the catalytic performance of the palladium(0)-mono-NHC complex (Table 5, entries 1-3). Similarly, the telomers were obtained nearly quantitatively with excellent chemo-and regioselectivities when the reaction was carried out in presence of the well- (29). However, catalysts with N-2,6-diisopropylphenyl-substituted carbene ligands gave comparatively lower regioselectivity with ratio n/ iso = 10-12:1 (Table 5, (30), whereas complex 28 yielded nearly no telomers (vide infra dimerisation reaction).…”

Preparation of a hybrid organic–inorganic material containing macrocyclic triolefinic 15-membered palladium(0) complexCatalytic activity in Suzuki cross-coupling and butadiene telomerization reactions

“…Surprisingly, the telomerization with methanol disappeared in favour of the butadiene dimerization when a large excess of alcohol was used (entry 4). For the butadiene dimerization, such a catalyst was, however, not competitive with the different systems developed, as recently reported [20].…”

Functional Elastomers via Sequential Selective Diene Copolymerization/Hydrophosphorylation Catalysis

“…Isoprene (Aldrich, 99.98%) was distilled twice from CaH 2 , stored under argon and degassed by freeze-thaw-vacuum cycles prior to use. 1,3,7-Octatriene, [7] complex (allyl) 2 NdClA C H T U N G T R E N N U N G (MgCl 2 ) 2 A C H T U N G T R E N N U N G (THF) 4 (1), [5] and cyclic phosphonate 2 [11] were prepared according to literature procedures. MAO (Albermale, 30 wt% solution in toluene) was used as received.…”

“…[1,4] In particular, we have recently shown that the simple, readily available binary combination (allyl) 2 NdClA C H T U N G T R E N N U N G (MgCl 2 ) 2 A C H T U N G T R E N N U N G (THF) 4 / MAO (MAO = methylaluminoxane) leads to high catalytic activity and high degree of control for isoprene polymerization, producing up to 98.5% 1,4-cis-polymers with number average molecular weights (M n ) in good agreement with calculated values and relatively narrow molecular weights distributions (M w /M n ). [5] Ziegler-Natta catalysts are also quite effective for co-polymerizing simple 1,3-dienes (butadiene, isoprene); [6] although, their copolymerization with wvinyl-1,3-dienes (e.g., the readily available 1,3,7-octatriene prepared by dimerization of butadiene) [7] is essentially unprecedented in the literature. [8] Such a copolymerization should lead to polydienes with pendant vinyl groups, offering unique opportunities for further chemical functionalization.…”