CO–ethene copolymerisation catalysed by [PdCl2(PPh3)2]/PPh3/HCl in MeOH

Abstract

The system [PdCl 2 (PPh 3 ) 2 ]/PPh 3 /HCl catalyses the carbonylation of ethene in MeOH as a solvent to give methyl propanoate (MP) or a polyketone (PK).The influence of temperature, Pd/P, CO/ethene and Pd/HCl ratios, and concentration of H 2 O on the catalytic activity has been studied. The catalytic system is active only in the presence of HCl and is stable when P/Pd is ≥6/1 up to 110• C. At 100• C, with Pd/P/HCl = 1/6/1600 (HCl initially added), under 6.0 MPa total pressure, the main product is MP at 1.0 MPa of ethene, whereas is PK when the pressure of the olefin is higher than 4.0 MPa.Water, which forms in the solvent, because of the reaction of MeOH with HCl, has a minor effect. The PK product presents a 2.5-4/1 ratio between the keto and ester end groups. The proposed catalytic cycle takes into account the results.

Carbonylation of Ethene Catalysed by Pd(II)-Phosphine Complexes

“…150 as (moles of ethene absorbed)(mol·Pd·h) −1 , whereas when ethene:CO = 40:20, the main product is a PK of moderate M n (2000–2500 g·mol −1 , TOF = 300 h −1 ), the formation of MP being almost suppressed. It was suggested that the acid, in addition to stabilizing the Pd-H initiator, could also destabilize the β- and γ-chelates through protonation of the oxygen atoms coordinating the metal centre, thus easing the chain growing process [68].…”

Ferrocenylmethylphosphanes and the Alpha Process for Methoxycarbonylation: The Original Story

“…Tooze et al modified the process to produce methyl propanoate, which is the most straightforward "polymer" obtained after quenching with methanol, i.e., the process operates for one cycle only (Figure 3). Since the initial development work on ethene-CO polymerisation by Drent, the mechanism of this process has been well studied [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Tooze et al modified the process to produce methyl propanoate, which is the most straightforward "polymer" obtained after quenching with methanol, i.e., the process operates for one cycle only (Figure 3).…”