Amines copper

Polymerization Mechanism. The mechanism that accounts for the experimental observations of oxidative coupling of 2,6-disubstituted phenols involves an initial formation of aryloxy radicals from oxidation of the phenol with the oxidized form of the copper—amine complex or other catalytic agent. The aryloxy radicals couple to form cyclohexadienones, which undergo enolization and redistribution steps (32). The initial steps of the polymerization scheme for 2,6-dimethylphenol are as in equation 6. 

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

The oxidative coupling of 2,6-dimethylphenol to yield poly(phenylene oxide) represents 90—95% of the consumption of 2,6-dimethylphenol (68). The oxidation with air is catalyzed by a copper—amine complex. The poly(phenylene oxide) derived from 2,6-dimethylphenol is blended with other polymers, primarily high impact polystyrene, and the resulting alloy is widely used in housings for business machines, electronic equipment and in the manufacture of automobiles (see Polyethers, aromatic). A minor use of 2,6-dimethylphenol involves its oxidative coupling to... 

Poly(phenylene ether). The only commercially available thermoplastic poly(phenylene oxide) PPO is the polyether poly(2,6-dimethylphenol-l,4-phenylene ether) [24938-67-8]. PPO is prepared by the oxidative coupling of 2,6-dimethylphenol with a copper amine catalyst (25). Usually PPO is blended with other polymers such as polystyrene (see PoLYETPiERS, Aromatic). However, thermoplastic composites containing randomly oriented glass fibers are available. 

Voluminous corrosion products are usually absent, as most copper amine complexes are quite soluble. Adjacent to corroded areas, one often finds small amounts of corrosion products and deposits colored a vivid blue-green by compounds containing liberated copper ion. 

Copper amine azide Copper tetramine nitrate Crotonaldehyde, stabilized Cyanogen bromide Cyanuric triazide... 

Copper amine oxidases structure and function. B. Mondovi and P. Riccio, Adv. Inorg. Biochem., 1984, 6, 225 (116). 

Poly(2,6-dimethyl-l,4-oxyphenylene) (poly(phenylene oxide), PPG) is a material widely used as high-performance engineering plastics, thanks to its excellent chemical and physical properties, e.g., a high 7 (ca. 210°C) and mechanically tough property. PPO was first prepared from 2,6-dimethylphenol monomer using a copper/amine catalyst system. 2,6-Dimethylphenol was also polymerized via HRP catalysis to give a polymer exclusively consisting of 1,4-oxyphenylene unit, while small amounts of Mannich-base and 3,5,3, 5 -tetramethyl-4,4 -diphenoquinone units are always contained in the chemically prepared PPO. 

Divalent Co substitution in copper amine oxidase revealed 19% of the native specific activity (for MeNH2) and 75% of the native reactivity toward phenylhydrazine. The major cause of this was a 68-fold increase in Km for 02. These investigations support the idea that electrons flow directly to bound 02 without the need for a prior metal reduction and that the Cu does not redox cycle but simply provides electrostatic stabilization during reduction of 02 to 02-. 1211... 

Laurenzi M, Tipping AJ, Marcus SE, Knox JP, Federico R, Angelini R, McPherson MJ (2001) Analysis of the distribution of copper amine oxidase in cell walls of legume seedlings. Planta 214 37 4-5... 

Rea G, Metoui O, Infantino A, Federico R, Angelini R (2002) Copper amine oxidase expression in defense responses to wounding and Ascochyta rabiei invasion. Plant Physiol 128 865-875 Roeder V, Collen J, Rousvoal S, Corre E, Leblanc C, Boyen C (2005) Identification of stress gene transcripts in Laminaria digitata (Phaeophyceae) protoplast cultures by Expressed Sequence Tag analysis. J Phycol 41 1227-1235... 

The use of bisethylenediamine copper (II) hydroxide solutions to effect solution of cotton has been practiced for many years and is still industrially practiced on a small scale as a method of regeneration of cotton. Copper-amine solutions were utilized for this study for a number of reasons including a. as noted above, an abundance of prior knowledge exists concerning the technique b. it allows fairly good solution of the cotton c. it was found, early in our work, to allow the execution of the types of modification desired and d. it is easily handled and can be utilized on the gram as well as ton scale. Further purity of modified material, i.e. effectiveness of removal of unreacted, etc. material is easily followed through analysis of the copper present in the modified material. 

It is well known that 2,6-dimethylphenol is oxidatively polymerized to poly(2,6-dimethyl-l,4-phenyleneoxide) with a copper amine complex as catalyst in the presence of oxygen at room temperature (Eq. 1)... 

However the formation of thin polymer film on the electrode, i.e. passivation of the electrode, resulted in cessation of the polymerization, which restricted the electro-oxidation as a polymerization procedure. The electro-oxidative polymerization as a method of producing poly(phenyleneoxide)s had not been reported except in one old patent, in which a copper-amine complex was added as an electron-mediator during the electrolysis (4). The authors recently found that phenols are electro-oxidatively polymerized to yield poly-(2,6-disubstituted phenyleneoxide)s, by selecting the electrolysis conditions This electro-oxidative polymerization is described in the present paper. 

Klinman JP. 2003. The multi-functional topa-quinone copper amine oxidases. Biochim Biophys Acta 1647 131. 

Amines such as diethylamine, morpholine, pyridine, and /V, /V, /V, /V -tetramethylethylene-diamine are used to solubilize the metal salt and increase the pH of the reaction system so as to lower the oxidation potential of the phenol reactant. The polymerization does not proceed if one uses an amine that forms an insoluble metal complex. Some copper-amine catalysts are inactivated by hydrolysis via the water formed as a by-product of polymerization. The presence of a desiccant such as anhydrous magnesium sulfate or 4-A molecular sieve in the reaction mixture prevents this inactivation. Polymerization is terminated by sweeping the reaction system with nitrogen and the catalyst is inactivated and removed by using an aqueous chelating agent. 

M. Mure, S.A. Mills, J.P. Klinman, Catalytic mechanism of the topa quinone containing copper amine oxidases. Biochemistry 41 (2002) 9269-9278. 

Allan S. Hay In the oxidative coupling of phenols with copper-amine catalysts and oxygen the evidence is quite compelling that the active catalyst has the structure... 

Lysine tyrosylquinone (LTQ). Another copper amine oxidase, lysyl oxidase, which oxidizes side chains of lysine in collagen and elastin (Eq. 8-8) contains a cofactor that has been identified as having a lysyl group of a different segment of the protein in place of the - OH in the 2 position of topaquinone.465 Lysyl oxidase plays an essential role in the crosslinking of collagen and elastin. 

Mechanisms. Studies of model reactions473-476 and of electronic, Raman,456 477 478 ESR,479/480 and NMR spectra and kinetics481 have contributed to an understanding of these enzymes.459 461 464 482 483 For these copper amine oxidases the experimental evidence suggests an aminotransferase mechanism.450 453 474 4743 d Tire structure of the E.coli oxidase shows that a single copper ion is bound by three histidine imidazoles and is located adjacent to the TPQ (Eq. 15-53). Asp 383 is a conserved residue that may be the catalytic base in Eq. 15-53.474b A similar mechanism can be invoked for LTQ and TTQ. 

Polymerization also takes place when 4-halo-2.6-disubstituted phenols are oxidized with copper-amine catalysts and oxygen (5,35). In this case, stoichiometric amounts of copper salt or some other chloride acceptor (inorganic bases or strongly basic amines) are necessary since the amine complexes of copper (II) halides are not catalysts for the polymerization. Blanchard (5) has also described the polymerization of these 4-halo-phenols under conditions similar to those used by Price using certain copper (II) complexes as initiators. 

In this copper-amine complex, electron transfer from oxygen to copper would give a phenoxy radical which, since the principal reaction of free phenoxy radicals appears to be C-C coupling, in this case must remain bound to the catalyst. Coupling of two of these radicals would then give dimer. 

Block copolymers may also be made by condensation polymerization. Elastomer fibers are produced in a three-step operation. A primary block of a polyether or polyester of a molecular weight of 1000-3000 is prepared, capped with an aromatic diisocyanate, and then expanded with a diamine or dihydroxy compound to a multiblock copolymer of a molecular weight of 20,000. The oxidative coupling of 2,6-disubstituted phenols to PPO is also a condensation polymerization. G. D. Cooper and coworkers report the manufacture of a block copolymer of 2,6-dimethyl-phenol with 2,6-diphenylphenol. In the first step, a homopolymer of diphenylphenol is preformed by copper-amine catalyst oxidation. In the second step, oxidation of dimethylphenol in the presence of the first polymer yields the block copolymer. 

A fourth possibility is the generation of H202 via oxidation of putrescine (butane-1,4-diamine 2.56). This reaction is catalyzed by copper amine oxidase (E.C. 1.4.3.6). Copper amine oxidases are homodimers in which each unit contains a copper ion and a 1,3,5-trihydroxyphenylalanine quinine co-factor. In plants copper amine oxidases generally oxidize putrescine to 4-aminobutanal (2.57). This latter compound undergoes spontaneous cyclization to A1 pyrroline (2.58), ammonia, and H202, as shown in Figure 2-12 (Medda et al., 1995). 

Figure 2-12. Formation of H202 via oxidation of putrescine by copper amine oxidase.

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