Condensation reactions organometallic polymers

Research involving condensation organometallic polymers was catalyzed by the observation that many organometallic halides possess a high degree of covalent character within their composite structure and that they can behave as organic acid chlorides in many reactions, such as hydrolysis... 

Materials that are constructed from organic polymers such as polyethylene, polystyrene, polyisoprene (natural rubber and a synthetic elastomer) and poly(vinyl chloride) are common features of our daily lives. Most of these and related organic polymers are generated from acyclic precursors by free radical, anionic, cationic or organometallic polymerisation processes or by condensation reactions. Cyclic precursors are rarely used for the production of organic polymers. 

Higher molecular weight polymers (40,000-50,000) have been reported from condensation reactions between monomer 6.15 and various silanediols, as illustrated in reaction (6).2 Polymer 6.16 can be melt-fabricated into films or fibers, which probably reflects the presence of roughly 100 repeating units per chain. However, the separation of the ferrocenyl units by the organic linker groups reduces the influence of the organometallic component. 

Radical and Condensation Polymerization. New classes of organometallic polymers have been isolated from the reaction of chloro-substituted polymers with alcohols or amines.168,169 170 The reaction of the acetylide, 86, with polymer 85 is shown in Scheme 2.27. Polymer 88 was isolated from the reaction of polymer 87 with hydrazine.169,170... 

The thermal reaction of cis or trans 1,4-poly(butadiene) with iron carbonyls results in geometrical isomerization of the alkenyl moieties and formation of polymers containing conjugated diene) iron tricarbonyl units. In the course of our continuing studies of the formation of stable colloidal iron dispersions by thermal decomposition of metal carbonyls in the presence of functional polymers, some aspects of this work have been repeated. Our objective was to isolate the soluble organometallic polymer which was intermediate to particle nucleation and independently examine the intramolecular condensation of metal atoms to yield metal clusters and metal particles. In this paper, the structure of the intermediate obtained on thermolysis of an excess of FeCCO) in a dilute xylene solution of c/5-poly(butadiene) has been described. 

The Une that divides classical and nonclassical metal complexes, organometallic complexes, and coordination compoimds is imperfect. For instance, what constitutes a coordination reaction and a condensation reaction Piperidine is an organic compound, that can react with metal-containing sites in two different ways. If the N-proton is retained, then the reaction is a coordination reaction and the resulting product a coordination compound. In this case, the nitrogen donates its lone pair of electrons to the metal site. However, if the proton is lost, then the reaction is described as a condensation reaction with the product called a condensation product. Polymers formed from such condensation reactions are covered in this volume. Schemes 1 and 2 depict reactions that illustrate the difference between coordination and condensation reactions using 1,6-hexanediamine. ... 

Two major approaches to the formation of materials of this type have involved the derivatization of preformed organic polymers with organometallic functions and the synthesis and polymerization of organometallic monomers that contain vinyl substituents For the transition metals, condensation polymerizations have also been investigated. However, the reactions have generally been conducted at elevated temperatures, and the resulting products have often not... 

The concept of transesterifications was used for polymerization reactions by Hedrick and colleagues [76]. Various biodegradable polyesters were synthesized with the l,3-dimethylimidazol-2-ylidene carbene in THF at 25 °C. Polymers such as poly(e-caprolactone) were obtained with no need of organometallic catalysts, as in classical methods. Poly(ethylene terephthalate) (PET) 97 was synthesized in the ionic liquid 98, which functions as the reaction medium and, at the same time, as a precatalyst that is activated (99) with KOt-Bu. Dimethyl terephthalate (DMT) 100 was condensed with an excess of ethylene glycol 101 to generate 102. The melt condensation of 102 was performed under vacuum using a heating ramp to 280 °C. 

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