Syndiotactic 1,2‐polybutadiene with Co‐CS₂ catalyst system. II. Catalysts for stereospecific polymerization of butadiene to syndiotactic 1,2‐polybutadiene

Abstract

SynopsisButadiene is polymerized by cobalt compound-organoaluminum-CSz catalysts to give highly crystalline syndiotactic 1,2-polybutadiene (s-PB) having melting point up to 216OC. An aluminum-free catalyst, CO(C4H6)(C8H13)-CS2, is also effective. Syndiotactic polymerization with C O ( C~H~) ( C~H~& C S~ is not interrupted by the addition of protic substances such as water and alcohol, but is influenced by donor or acceptor substances. The donor molecule, e.g., dimethylsulfoxide or dimethylformamide, decreases the stereoregularity, i.e., syndiotacticity and 1,2 content. An acceptor molecule of organoaluminum with appropriate acidity such as AlEt3-AlEtzCl or tetraethylaluminoxane increases the molecular weight, stereoregularity, and yield of the polymer. In the presence of CSz a mixture of cis-PB and s-PB was obtained by using Co(octoate)z-AlEtzCl-HzO, with molar ratio H20/Co less than unity. In the case of HzO/Co > 1, only cis-PB was obtained. By the addition of donor substances such as ester, ether, nitrile, and U t 3 , s-PB was obtained even when H20/Co > 1. The amount and ratio of cis-PB and s-PB are dependent upon the nature and amount of the additives. [43& = [7]gg&,, = 8.18 x 1 0 -5~~o . w a Polymerization conditions: benzene 860 mL, butadiene 85 g, at 4OoC with HzO (variable)-AlEta (3.0 mmol)-Co(acac)3 (0.045 mmol)-CSz (0.13 mmol) as the catalyst.

Novel Allyl Cobalt Phosphine Complexes: Synthesis, Characterization and Behavior in the Polymerization of Allene and 1,3-Dienes

“…This hypothesis, in our opinion, is also in agreement with the fact that allene can be polymerized also in absence of MAO; allene could coordinate with only one double bond, thus favoring the insertion of the coordinated 1,3-butadiene, and then inserting itself into the allyl group of the growing chain. On the other hand, a similar behavior was observed with the allyl cobalt complex (η 4 -C 4 H 6 )(η 5 -C 8 H 13 )Co, which was found to be extremely active in the polymerization of 1,3-butadiene to 1,2 polymers only if used in combination with CS 2 [12,15]. The different behavior, regarding activity and stereospecificity, exhibited by the various cobalt complexes in the polymerization of the different diene monomers is even more difficult to interpret, but it is, in some way, in agreement with that observed in the polymerization of 1,3-dienes with the catalytic systems CoCl2(PRPh2)2/MAO (R = methyl, ethyl n-propyl, i-propyl, cyclohexyl) [20,21].…”

“…Allyl derivatives of other transition metals (Ti, Zr, Mo, W, Ru, Rh, U, Nd) were later found to be effective catalysts [8][9][10]. More recently, the allyl cobalt compound (η 4 -C4H6)(η 5 -C8H13)Co, alone or in presence of CS2, was reported to be highly active and stereoselective in the polymerization of 1,3-butadiene to 1,2 syndiotactic polymer [11][12][13][14][15].…”

High Catalytic Activity and Stereoregularity of BF3 Etherate as Cocatalyst of Nd-Based Catalyst in the Polymerization of 1,3-Butadiene

“…Block of active center impedes 26 cisoid coordination of monomer with active center to give low 1,4-cis content. Nd-based catalysts may thus have stronger endurance to electron donor in catalytic activity and stereoregularity than the conventional Ziegler-Natta catalysts based on cobalt 25 and nickel. 27 A ternary catalyst system comprising Nd(versatateh/ Al(i-Buh/BF 3 etherate was observed to have high catalytic activity and stereoregularity in the polymerization of 1,3-butadiene to give conversion over 90% and 1,4-cis content over 97% under suitable conditions.…”

“…Surprisingly, even BF 3 thioetherate containing SMe 2 provided high catalytic activity in conversion and stereoregularity in 1,4-cis content, catalyst 11, although SMe 2 was expected to act detrimentally toward active centers. A Lewis base containing heteroatom such as sulfur, 25 even at low concentrations, deactivates the active center of Ziegler-Natta catalyst based on transition metal by complexing with it, thereby obstructing the approach of monomer to give low conversion. Block of active center impedes 26 cisoid coordination of monomer with active center to give low 1,4-cis content.…”

Polymer dispersions from catalytic polymerization in aqueous systems

“…The catalyst system, based on an 'in situ' prepared cobalt catalyst modified with CS 2 as a ligand, was previously developed for the 1,2-polymerization of butadiene in solution. 95 By addition of 'modifiers' the melting point of the polymer can be reduced. 96 In these reports little consideration was given to the colloidal state of the final reaction mixture, as the studies appeared to aim at isolation of the bulk polymer.…”