Acetylene-terminated polymers synthesis

The c/s-dihydroxylation reaction catalyzed by these dioxygenases is typically highly enantioselective (often >98% ee) and, as a result, has proven particularly useful as a source of chiral synthetic intermediates (2,4). Chiral cis-dihydrodiols have been made available commercially and a practical laboratory procedure for the oxidation of chlorobenzene to IS, 2S)-3-chlorocyclohexa-3,5-diene-l,2-c diol by a mutant strain of Pseudomonas putida has been published (6). Transformation with whole cells can be achieved either by mutant strains that lack the second enzyme in the aromatic catabolic pathway, cw-dihydrodiol dehydrogenase (E.C. 1.3.1.19), or by recombinant strains expressing the cloned dioxygenase. This biocatalytic process is scalable, and has been used to synthesize polymer precursors such as 3-hydroxyphenylacetylene, an intermediate in the production of acetylene-terminated resins (7). A synthesis of polyphenylene was developed by ICI whereby ftie product of enzymatic benzene dioxygenation, c/s-cyclohexa-3,5-diene-1,2-diol, was acetylated and polymerized as shown in Scheme 2 (8). 

Quan, Z. Zuju, M. Lizhong, N. Jianding, C. 2007. Novel phenyl acetylene terminated poly(carborane-silane) Synthesis, characterization, and thermal property. J. Appl. Polym. ScL, 104 2498-2503. 

Many trends in polymer synthesis generally are being applied, or could be applied in the future, to adhesives. There is a continuous stride toward polymers with superior heat resistance. To achieve this, various heterocyclic and aromatic structures are built into polymers, e.g., by intramolecular cyclization (polyimides, polybenzimidazoles), trimerization of terminal acetylene or nitrile groups, etc. Another route is to introduce highly stable perfluorinated units into the polymer. While heat-resistant polymers find their main applications as laminating... 

Diacetylenes in phospholipid bilayers have been the subject of extensive studies in our laboratory, not only because of the highly conjugated polymers they form, but also because of their ability to transform bilayers into interesting microstructures. Consequent to our synthesis and characterization of several isomeric diacetylenic phospholipids, we have found that the polymerization in diacetylenic bilayers is not complete. In order to achieve participation of all diacetylenic lipid monomer in the polymerization process, diacetylenic phospholipid was mixed with a spacer lipid, which contained similar number of methylenes as were between the ester linkage and the diacetylene of the polymerizable lipid. Depending upon the composition of the mixtures different morphologies, ranging from tubules to liposomes, have been observed. Polymerization efficiency has been found to be dependent on the composition of the two lipids and in all cases the polymerization was more rapid and efficient than the pure diacetylenic system. We present the results on the polymerization properties of the diacetylenic phosphatidylcholines in the presence of a spacer lipid which is an acetylene-terminated phosphatidylcholine. 

As mentioned in the introduction, the synthesis of telechelics is important to preparative polymer chemistry because of their use as macromonomer precursors (and therefore graft copolymer and network precursors), as precursors to block copolymers, and as the basis of reaction injection molding. Some general reviews on telechelics include those of A they and Heitz. In addition, the synthesis, reactions and properties of acetylene-terminated oligomers were recently reviewed.An extensive discussion of this class of reactive polymers is the subject of a recent book. ... 

As in the case of the ring-opening metathesis polymerisation of cycloolefins, an important matter is the control of polymerisation to prepare acetylenic polymers having precise structures. A living polymerisation is of practical importance in the synthesis of monodisperse polymers, such as terminally functionalised polymers and block copolymers. The metathesis catalysts that promote the living polymerisation of acetylene [42] and acetylenic monomers include M0OCI4 SnBu EtOFkNbCls and Ta, Mo and W alkylidenes [84, 133, 152, 153]. 

One can envision three possible scenarios for adapting this chemistry to an insoluble-polymer-supported synthesis mask the terminal acetylene or the aryl iodide with the polymer, or link the sequence to the support through a pendant functional group. The efforts described here focus on the strategy of using the insoluble polymer as a masked aryl iodide by attaching functionalized aromatic monomers to polystyrene beads via the l-aryl-3,3-dialkyl triazene group as shown in Scheme 12-8. 

Several examples of the application of Pd/Cu-catalyzed cross-coupling for synthesis of alkynyl ketones, terminal acetylenes, enediyne macrocycles, and enediyne polymers are given. 

For modular synthesis of ABC-type triblock copolymer, two successive CuAAC reactions have to be performed on the central polymer chain (B block). To accomplish this, the B block polymer having both azide and acetylene end groups (heterotelechelic B) has to be used and, moreover, one of the termini has to be protected in order to prevent linear chain extension (cf Scheme P12.2.1) or formation of cyclic products (Scheme P12.4.1). In a straightforward methodology, the terminal acetylene moiety on B is protected and the azide terminus is used to carry out the rst coupling reaction to join the preformed A or C block. Next, the acetylene moiety is to be deprotected to make it available for the second coupling reaction to join the remaining C or A block. 

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