Regio‐ and stereo‐selective alternating copolymerization of carbon monoxide with propene

Abstract

SUMhL4RYCompounds of palladium with ten different chelated bisphosphine ligands were investigated for their catalysis of alternating copolymerization of propene with carbon monoxide. The bisphosphine structure and chelate ring size influence strongly the activity, regio-and stereoselectivity of the catalysts. Molecular mechanics calculations on the x-olefin complex showed that the non-bonded interaction between propene and the ligands on Pd is both regio-and stereoselective. Primary insertion is about seven times more probable than secondary insertion for the Pd complex of bis(dipheny1phosphino)butane ligand. The enantioselective catalysts favor the meso enchainment of propene. Gas chromatography/mass spectrometry (GC-MS) of oligomers showed that most chains are initiated by Pd-H species with less frequent initiation by Pd-OCH, complexes; B-hydrogen elimination is the dominant chain termination process.a) The abstract (ref. ')) disclosed a catalyst comprising Pd acetate, Ni perchlorate, asymmetric 1,3-bis[bis(2-methoxyphenyl)phosphino]propane, 1,Cnaphthoquinone in toluene/methanol solvent mixture which copolymerizes a-olefins with three or more carbon atoms and carbon monoxide. No properties of the copolymers were given. 0 1993, HIithig & Wepf Verlag, Basel CCC 0025-1 16X/93/%05.00 2580 F. Y. Xu, A. X. Zhao, C. W. Chienregio-and stereo-regularity. Gas chromatography/mass spectrometry (GC-MS) of P/CO oligomers led to the understanding of the chain initiation, propagation, and termination processes. The structure of the bisphosphine ligand was varied to study the effect of its chelation on the regio-and stereo-chemical control in the P/CO copolymerization. These results are communicated in this paper. Experimental part MaterialsPropene (CP grade, 99% minimum), carbon monoxide (CP grade, 99,0% minimum) and argon (prepurified, 99.998% minimum) were supplied by Linde Gas Co., U. S. A. Most chemicals were purchased from Aldrich Chemical Co., U. S. A. Some phosphines were the gifts of Texas Eastman Chemical Co., U. S. A. Acetonitrile, 1,2-dichloroethane, and methanol were purified as described in the previous papersss6). (1) according to previously given procedures ', 'I. Synthesis of [Pd(CH3CN)d(BF& Compound 1 was prepared by the reaction of Pd sponge with NOBF, in acetonitrile solution Synthesis of [(Ph2P(CH2),PPh3Pd(CH3CN)&BF& (catalyst 2, dppe ligand)The reaction of (Ph2P(CH,),PPh3PdC1, (5,76 g; 10 mmol) with AgBF, (3,89 g; 20 mmol) in 150 mL of acetonitrile was carried out at room temperature for 6 h. The white solid product was filtered and excess acetonitrile removed with evacuation. The yellow colored 2 was obtained in ca. 95% yield. Synthesis of [(Ph2P(CHJ,,PPh9Pd(CH3CN)J(BF.Jz (catalyst number) ligand (3) dpppr, (4)dpph (5) dpppe, (6) dpph These catalysts were synthesized by reacting 1 (0.444 g; 1 mmol) with Ph,P(CH,),PPh, (1 mmol) in 150 mL acetonitrile. The product was worked up as for 2.

Synthesis and Polymerization Performance of PdII Complexes of New 2‐Hydroxyethyl‐Substituted Diphosphane Ligands

“…Strem Chemicals), ethylene oxide (Fluka), AgBF 4 and (dppp)PdCl 2 (Aldrich), and 2-norbornene (Merck) were used as received. (COD)PdCl 2 [14] and (CH 3 CN) 2 (dppp)Pd(BF 4 ) 2 [15] were prepared according to literature procedures. 1 H, 13 C, 19 F, and 31 P NMR spectra were recorded on either a Bruker DRX 400 or an AMX 500 spectrometer.…”

Homo- and Copolymerization of Strained Cyclic Olefins with New Palladium(II) Complexes Bearing Ethylene-Bridged Heterodonor Ligands

“…The ligands (SxAs) (1) and (SxP) (2) were prepared according to literature procedures. [11] [Pd(NCCH 3 [12] (6) were prepared following a previously published procedure: [13] A filtered solution of the ligand (0.675 mmol) in CH 3 CN (15 ml) was added to a filtered solution of [Pd(NCCH 3 ) 4 ](BF 4 ) 2 (0.30 g, 0.675 mmol) in CH 3 CN (15 ml). After 5 h of stirring at room temperature, the solvent was evaporated in vacuum to produce a yellow solid in over 85% yield.…”

Side-chain liquid-crystalline poly(ketone)s: effect of spacer length, mesogen type and mesogen density on mesomorphic behavior

“…[12] CH 2 Cl 2 was distilled from CaH 2 and methanol was treated with sodium methoxide/dimethylterephthalate and subsequently distilled. All other chemicals were of commercial grade and were used as received.…”

“…No spectroscopic indication was found for the formation of spiroketal units, [34,35] which have been observed before for some other poly(ketone)s. [30,34] Jiang et al [34] postulated a possible mechanism for spiroketal formation and found that the cyclization appears to be favored in a regio/stereo regular disposition of the carbonyl groups. Previous studies, [12] however, have shown that the copolymerization of carbon monoxide with propene using [Pd(dppp) (NCCH 3 ) 2 ](BF 4 ) 2 as a catalyst yields regiochemically random copolymers and therefore will not result in copolymers containing spiroketal units.…”

“…These mesogens may be present in the backbone (main-chain liquid-crystalline polymers) or attached to the backbone via flexible spacers (side-chain liquid-crystalline polymers, SCLCPs). A great variety of polymer backbones has been used for SCLCPs, like poly(acrylate)s, [1] poly(siloxane)s, [2] poly (phosphazene)s, [3] poly(styrene)s, [4] and poly(maleic anhydride-alt-1-alkene)s. [5] A completely new type of polymer backbone for SCLCPs may be poly(1,4-ketone)s. Throughout the past few years, poly(1,4-ketone)s have attracted a growing attention by academic [6][7][8][9][10][11][12][13] as well as industrial research groups. [14][15][16][17][18] Evidently, this is related to the fact that carbon monoxide (CO) is a low price monomer.…”