Phenylacetylene polymerisation

Rarely involved in dangerous polymerisation reactions. However, phenylacetylene... 

Trumbo, D. L. et al J. Polym. Sci., A, Polymer Chem., 1987, 25, 1027-1034 Among palladium(II) salts used to polymerise phenylacetylene, the acetate led to rapid and very exothermic polymerisation, sometimes leading to explosion. 

It is worth noting that suitable olefins added to the polymerisation system can act as chain transfer agents during the metathesis polymerisation of acetylenic monomers for instance, trimethylvinylsilane has been found [84] to be an effective chain transfer agent in the polymerisation of phenylacetylene in the presence of the WC16—SnPh4 catalyst. 

Interesting evidence supporting the mechanism of polymerisation of acetylenes via carbene species is provided by the block and random copolymerisation of acetylenic monomers with cycloolefins. For instance, block copolymers of acetylene and cyclopentene with the WC —AlEtCT catalyst [41] and block copolymers of acetylene and norbornene with the (MeA. Oj2W(=NAr)= CHMe3 catalyst [42] have been obtained moreover, random copolymers of phenylacetylene and norbornene with the WC16 catalyst have also been obtained [149, 150],... 

Kishimoto, Y., Noyori, R., Eckerle, P., Miyatake, P. and Ikariya, T., Stereospecific Living Polymerisation of Phenylacetylene with Rh Complexes , in The Polymeric Materials Encyclopedia, CRC Press, Inc., Boca Raton, 1996, Vol. 7, pp. 5051-5055. 

A series of ionic liquids have been tested for the polymerisation of phenylacetylene with the pyrazolylborate rhodium complexes 46 and 47, shown in Scheme 8.13.[701 Complex 46 afforded higher molecular weights and lower polydispersity at comparable activity in the ionic liquid relative to dichloromethane. The addition of small amounts of methanol to the ionic liquid was found to have a positive effect on the catalytic activity. With complex 47 best results were obtained in [C4Ciim]Cl, giving 64% yield after 2 hours at 65°C. Molecular weights were usually lower with 46 than those obtained with either 47a or 47b as catalyst. 

Masuda et studied the polymerisation of phenylacetylene catalysed by tungsten hexachloride and molybdenum pentachloride in benzene at 30 °C. Water cocatalysis was qualitatively established, although the authors claimed that the monomer itself could also act as a cocatalyst. This conclusion is however in apparent ccxitradiction with the fact that polymer yields were incomplete. The only way to reconcile these two phenomena would be that terminating species were produced capable of inhibiting further initiation. 

Material scientists have exploited a range of ferritin superfamily proteins as supramolecular templates to encapsulate nanoparticles and/or as well-defined building blocks for fabrication of higher order assembly. For example, the organometallic Rh(nbd) (nbd = norbomadiene) can be immobilised at specific sites within the apoferritin molecule where it can catalyse the polymerisation of phenylacetylene within the protein shell (Figure 19.10). This is but one example of the quest to develop highly effective artificial metalloenzymes by rational design of metal coordination sites within the ferritin molecule. 

FIGURE 19.10 A schematic illustration of immobilisation of [Ru(nbd)Cl]2 complex into apoferritin cage followed by polymerisation of phenylacetylene catalysed by the ferritin. The polymerisation reaction occurs site-specifically inside of the ferritin cage. (From Uchida, Kang, Reichhardt, Harlen, Douglas, 2010. Copyright 2010 with permission from Elsevier.)... 

The binuclear compounds as well as the mononuclear seven-coordinate bis(nitrile) compounds are catalysts for the polymerisation of terminal alkynes such as phenylacetylene (PA) or ferf-butylacetylene (f-BA) and for the ROMP of norbornene (NBE) and norbornadiene (NBD) [20, 38-42]. The first step in all catalytic reactions is the coordination of the organic substrate to metal and the formation of a complex. Sometimes it was possible to isolate the products in crystalline form but frequently such adducts were observed only in situ by NMR investigations. 

The polymerisation of unsubstituted phenylacetylene into trans-po y-phenylacetylene was achieved by Buchmeiser and co-workers using a related alkoxybenzylidene ruthenium initiator (37) bearing a six-membered NHC and pseudohalide ancillary ligands (Scheme 7.11). Interestingly, when the ruthe-nium-arene complex 34 was employed as catalyst, only oligomers (pentamers... 

Ruthenium complex 81 reacted with alkynes yielding 82, which underwent migratory insertion of the NHC ligand into the Ru alkylidene to form 83 (Scheme 2.26). Trzeciak and co-workers demonstrated that [(NHC) RuCl2(Ti -p-cymene)] was able to polymerise phenylacetylene, and that the resulting product was terminated by an imidazolium species, probably via the same process. ... 

The iron species [Fe(X)2 CN(PP)CH(Me) = CH(Me)N(Pr ) ] (X = Cl, Br), containing highly donating imidazolyidene ligands, have been found to be extremely active and efficient catalysts for the atom transfer radical polymerisation of styrene and methylmethacrylate. A variety of indenyl ruthenium complexes containing either phenylacetylide (C = CPh) or vinyl (CH = CHPh) ligands have been found to catalyse the dimerisation of phenylacetylene to ( )-and (Z)-l,4-diphenyl-l-en-3-yne with the activity of the catalyst dependent upon the nature of the phosphine co-ligand bound to ruthenium. The vinylidene-ruthenium(II) complexes [Ru(Cl)(L)2(C = CHR)] (R = Bu, ferrocenyl L =... 

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