Copper polymer complexes reactivity

Less often, metal carbonyls are replaced by other precursor compounds. Examples include metal formates, acetates, and oxalates, and various organometaUic compounds. Recently, a metal-polymer composition of the Claspol type was obtained by the thermolysis of a triethylenediamine complex of copper formate [Cu(En)3]-(HC(X))2 in PS using dimethylformamide as the common solvent. " This complex disintegrates at 170°C to form metallic copper in a highly dispersed state. This temperature is 20°C lower than that of the thermolysis of the initial pure copper formate complex. The polymer has a catalytic effect on the thermal degradation of this complex. The reactive centers of the polymer favor the formation of metal particle nuclei, which are centers of aggregation. This is followed by the thermolysis and redistribution of the copper complex. The maximum quantity of copper that can be incorporated into PS is 10%. 

Thus, polydispersities decrease with conversion, p, with the rate constant of deactivation, k, and with the eoneentration of deactivator, [X-Cu(II)], however, they increase with the propagation rate eonstant, kp, and the concentration of initiator, [RX] . This means that more uniform polymers are obtained at higher conversions, when the concentration of deactivator in solution is high and the eoneentration of initiator is low. Also, more uniform polymers are formed when the deaetivator is very reactive (e.g., copper(II) complexed by bipyridine or triamine) and monomer propagates slowly (e.g., styrene rather than acrylate). 

Copper (II) salts have been found to be inactive as catalysts for the reaction with the exception of the copper (II) carboxylates which are considerably less reactive. In addition, the polymerization of 2.6-xylenol in pyridine with copper (II) acetate as catalyst appears to terminate before high molecular weight polymers are formed. However, treatment of an amine complex of a copper (II) salt with an equivalent of a strong gives the active catalyst. Similarly, although copper (II) hydroxide in pyridine is inactive as a catalyst, treatment with an equivalent of hydrogen chloride generates the active catalyst. Hence it can be concluded that the active catalyst is a basic salt (XV). 

Oxidative coupling polymerization provides great utility for the synthesis of high-performance polymers. Oxidative polymerization is also observed in vivo as important biosynthetic processes that, when catalyzed by metalloenzymes, proceed smoothly under an air atmosphere at room temperature. For example, lignin, which composes 30% of wood tissue, is produced by the oxidative polymerization of coniferyl alcohol catalyzed by laccase, an enzyme containing a copper complex as a reactive center. Tyrosine is an a-amino acid and is oxidatively polymerized by tyrosinase (Cu enzyme) to melanin, the black pigment in animals. These reactions proceed efficiently at room temperature in the presence of 02 by means of catalysis by metalloenzymes. Oxidative polymerization is observed in vivo as an important biosynthetic process that proceeds efficiently by oxidases. 

The self-condensing copper-catalyzed polymerization of macromonomer of poly(tBA) with a reactive C—Br bond (H-6) affords hyperbranched or highly branched poly(tBA).447 Copolymerization of H-1 and TV-cyclohexylmaleimide induced alternating and self-condensing vinyl polymerization.448 The residual C—Cl bond was further employed for the copper-catalyzed radical homopolymerization of styrene to give star polymers with hyperbranched structures. Hyperbranched polymers of H-1 further serve as a complex multifunctionalized macroinitiator for the copper-catalyzed polymerization of a functional monomer with polar chromophores to yield possible second-order nonlinear optical materials.325... 

Analysis of the Structures. In the following, questions concerning the stereoregularity of the polymer and the origin of the photoinactivity of the copper salts will be answered. For this purpose, the crystal structures of the reactive cadmium chloride complex salt 2 as monomer and polymer, and of the corresponding copper salt i. have been solved by x-ray diffraction. 

Given the utility of chiral Cu(II)/bisoxazoline complexes in enantioselective Mukaiyama aldol reactions, a number of reports detailing the development of polymer-bound or dendritic bisoxazoline copper (I I) complexes have been developed. Development of such catalyst systems provides the potential for easy recovery and reuse of the relatively expensive catalyst. To this end, Salvadori and CO workers reported Mukaiyama aldol addition of ketene thioacetal (57) to methyl pyruvate catalyzed by a Cu(OTf)2 complex of polystyrene-supported bisoxazoline (89) (Scheme 17.18) [23]. The enantioselectivity of the addition remained high over eight cycles of the catalyst, however, reactivity was gradually reduced over time. 

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