Influence of the operating conditions on the catalytic activity of [PdCl2(dapp)] in the CO–ethene copolymerization in the H2O–CH3COOH as a solvent (dapp=1,3-bis(di(2-methoxyphenyl)phosphino)propane)

Abstract

a b s t r a c tThe influence on the productivity of [PdCl 2 (dapp)] in H 2 O-CH 3 COOH in the CO-ethene copolymerization and on the LVN of the copolymer of the following reaction parameters has been studied: (i) composition of the H 2 O-CH 3 COOH reaction medium; (ii) temperature; (iii) CO/ethene ratio at a given total pressure; (iv) total pressure at fixed ratio CO/ethene = 1/1; (v) CO or ethene partial pressure at a given pressure of one monomer; (vi) reaction time. High molecular weight PKs are obtained under high pressure with the monomers in the ratio 1/1 at relatively low temperature and with a H 2 O/CH 3 COOH 40-50% with productivity ranging from 4 to 20 kg PK(g Pd h) −1 . The relation between productivity and LVN has been discussed in the light of the key steps of the catalytic cycle.

Influence of formic acid and water on the [Pd(OAc)2(dppp)] catalyzed ethene–carbon monoxide copolymerization carried out in aprotic organic solvents

“…2), in contrast with what observed in H 2 O AcOH [21,23]. The trend suggests a direct involvement of the acid in the chain termination step (see below).…”

“…In addition, it can be due to the lowering of the solubility of the monomers. In order to further improve the catalyst performance, we tested also the influence of H 2 O, which can be a hydride source for the catalyst [23][24][25].…”

“…The copolymerization is carried out preferably in methanol, although in some interesting papers water has been proposed as an alternative solvent [12][13][14][15][16][17]. We found that the precursors [PdX 2 (P-P)] (X = AcO, Cl), inactive in MeOH, turn into highly active catalysts when used in H 2 O AcOH or H 2 O HCOOH [18][19][20][21][22][23][24][25].…”

The Catalytic Copolymerization of Ethene with Carbon Monoxide Efficiently Carried out in Water-Dichloromethane-Sodium Dodecylsulfate Emulsion

“…The catalytic activity (but also the PK molecular weight), however, strongly depends also by the reaction conditions (temperature, pressure of monomers and batch time [14][15][16][17][18][19][20]), and by the nature of the solvent [21]. On regard to the solvent, methanol is the most widely used even though water, which represents the ideal choose in terms of sustainability, is used too.…”

“…On regard to the solvent, methanol is the most widely used even though water, which represents the ideal choose in terms of sustainability, is used too. The reactions carried out in water, however, usually lead to PK with higher molecular weight in comparison to the polymer obtained in methanol as a solvent [19][20][21][22]. As matter of fact, the more active catalysts (used for the reaction in methanol) are inactive or poorly active in water, because unsolvable.…”