73727-99-8

Upstream product

• 3375-31-3 palladium diacetate 
• 1663-45-2 1,2-bis-(diphenylphosphino)ethane 
• 14724-41-5 diacetato(2,2'-bipyridine)palladium(II) 

Downstream Products

• 3375-31-3 palladium diacetate 
• 7440-05-3 palladium 
• 399039-48-6 [Pd(CH₃C₆H₄SO₂O)2(1,2-bis(diphenylphosphino)ethane)] 

Relevant academic research and scientific papers

Taking too many precautions in making a catalyst is never a loss of time: A lesson we learned at our own expense

The reaction in MeOH between the bis-chelate complex [Pd(dppe)2](OAc)2 and Pd(OAc)2 to give the monochelate product Pd(OAc)2(dppe) is assisted by free acetate ion, and its rate is proportional to the concentrations of both reagents (dppe = 1,2-bis(diphenylphosphino)-ethane). The aggregation of Pd(OAc)2 in CH2Cl2 and the low dielectric constant of this solvent are proposed to be important factors in accelerating the formation of Pd(OAc)2(dppe) in CH2Cl2.

Palladium catalyzed oxidative carbonylation of alcohols: Effects of diphosphine ligands

The catalytic activity of a series of palladium diphosphine complexes of the type [PdX2(P∩P)] has been studied in the oxidative carbonylation of i-PrOH with p-benzoquinone as an oxidant. Diphosphine ligands have been chosen in order to cover a wide range of bite angles and electronic and steric parameters. Their properties have been correlated with the catalytic activity and selectivity of the reaction. The best catalytic performance has been achieved with weakly coordinating anions as well as non-bulky and electron-donating P∩P ligands with a relatively wide bite angle yet capable of maintaining a cis-coordination, such as cis-[Pd(OTs)2(pMeO-dppf)]. These results and those on the reactivity of dicarboalkoxy species of the type cis-[Pd(COOMe)2(P∩P)] toward reductive elimination, which is a crucial step in oxalate formation, suggest that the slow step of the catalysis depends on the nature of the P∩P ligand.

In situ preparation of palladium diphosphane catalysts

The efficiency of a superficially simple preparation procedure for palladium-diphosphane catalysts has been examined. Preparation of Pd(dppe)X2 in situ by mixing equimolar amounts of Pd(OAc)2 and 1,2-bis(diphenylphosphanyl)-ethane (dppe) in methanol in the first step unexpectedly affords the bischelate [Pd(dppe)2](OAc)2 as the (main) kinetic product. Subsequently, the slow reaction of [Pd(dppe)2]-(OAc)2 and unreacted Pd(OAc)2 forms the thermodynamically favored monochelate [Pd(dppe)(OAc)2] (following first-order kinetics). Conversion of the bischelate into the monochelate stops after addition of strong acid (HX) in the second step, thus affording a mixture of active - Pd(dppe)X2 - virtually inactive - [Pd(dppe)2]X2 - and unstable - PdX2 - species. This procedure was also evaluated for some other diphosphane ligands and methods are given to overcome the encountered problem.

Ligand and solvent effects in the alternating copolymerization of carbon monoxide and olefins by palladium-diphosphine catalysis

The substitution of two hydrogen atoms by methyl groups in the 1,2 positions of 1,2-bis-(diphenylphosphino)ethane (dppe) gives meso- and rac-2,3-bis(diphenylphosphino)butane (meso-2,3-dppb and rac-2,3-dppb). The corresponding Pd(II) complexes Pd(OTs)2(meso-2,3-dppb) and Pd(OTs)2(rac-2,3-dppb) are effective catalyst precursors for the alternating copolymerization and terpolymerization of carbon monoxide with ethene and ethene/propene in MeOH with productivities that are higher than those of the unsubstituted dppe catalyst Pd(OTs)2(dppe) even by a factor of 10 (OTs = p-toluenesulfonate). It has been found that the low productivity of the dppe-based catalyst in MeOH is due to the autoionization of the precursor Pd(OAc)2(dppe) in MeOH to give the catalytically inactive bis-chelate species [Pd-(dppe)2](OAc)2 and palladium acetate. In an attempt to evaluate and rationalize the effective ligand control on the intrinsic catalytic activity, the methyl complexes [Pd(Me)(MeCN)(P-P)]PF 6 have been synthesized and employed in CH2Cl2 to catalyze the alternating carbon monoxide/ethene copolymerization. The intrinsic activity of the three precursors decreases in the order [Pd(Me)(MeCN)(meso-2,3-dppb)]+ > [Pd(Me)(MeCN)(rac-2,3-dppb)] + > [Pd(Me)-(MeCN)(dppe)]+. High-pressure NMR experiments and the determination of activation barriers of migratory insertions agree to indicate the relative stability of the β-chelate ring in [Pd(CH2CH2C(O)Me)(P-P)]+ as the factor that controls the copolymerization rate in aprotic solvents. The impact of the different diphosphines on both productivity and intrinsic catalytic activity has been attributed to the different stereochemical rigidity of the Pd(P-P) five-membered metallarings. The β-chelate complexes [Pd(CH 2CH2C(O)Me)(P-P)]PF6 with diphosphine ligands containing two carbon atoms between the phosphorus donors have been isolated for the first time and employed to study the chain-transfer by protonolysis, which proceeds via the enolate mechanism. It has been shown that the chain-transfer products [Pd(OH)(P-P)]22+ do not represent a dead end for the alternating CO/ethene copolymerization.