Copper salts stabilization

Copper-based thermal stabilizers are also effective photostabilizers for nylon. They can be added before polymerization, or the soluble salts (eg, CuSO can be appHed to fibers as part of the finish or to fabrics as post-treatments. The effectiveness of the copper salt—alkah haUde system added to prepolymer in retarding phototendering and photoyeUowing of the resulting spun yam is illustrated in Figure 5. 

Copper Hydroxide. Copper(II) hydroxide [20427-59-2] Cu(OH)2, produced by reaction of a copper salt solution and sodium hydroxide, is a blue, gelatinous, voluminous precipitate of limited stabiUty. The thermodynamically unstable copper hydroxide can be kiaetically stabilized by a suitable production method. Usually ammonia or phosphates ate iacorporated iato the hydroxide to produce a color-stable product. The ammonia processed copper hydroxide (16—19) is almost stoichiometric and copper content as high as 64% is not uncommon. The phosphate produced material (20,21) is lower ia copper (57—59%) and has a finer particle size and higher surface area than the ammonia processed hydroxide. Other methods of production generally rely on the formation of an iasoluble copper precursor prior to the formation of the hydroxide (22—26). 

Copper proteins, 1,168 5,720 models, 2,85 nonblue, 5,723 type 111, 5,724 Copper salts cellulose dyes, 6,38 Copper(I) salts stabilization, 6,786 Copper(II) salts ammoniacal leaching, 6,787 oxidant... 

The rate of release of NO from SNAP in the absence of any copper ions (the spontaneous or thermal reaction) is very slow indeed. The reason for the very low stability of nitrosocysteine is that there is a ready complexation of copper ions to this compound, a process that is the precursor of NO release [18]. Further studies by Butler and Williams [19] showed that it is the cuprous ion, Cu(I), which is the active species in effecting NO release from a nitrosothiol, whatever copper salt is present in solution. Cuprous ions are readily generated from Cu(II) by reaction with a thiol ... 

As indicated in Section ni.B, deprotonation of a carbamate affords a dipole-stabilized a-amino-organolithium that can be transmetalated with copper salts to form cuprates, thereby expanding the versatility of the organolithium. Suitable electrophiles include enones, alkenyl, alkynyl, allenyl and dienyl carboxylic acid derivatives, nitriles and sulfoxides. Dieter and coworkers have shown that the same process can be accomplished via transmetalation of a stannane (Scheme 36). The procedure is particularly... 

Three general trends are noted in the "ON" state character of the copper and silver complexes as related to the different acceptor molecules. The first is that the copper salts consistently exhibited greater stability and reproducibility over the corresponding silver salts of the same acceptor. Second, it is... 

Transmetallation of the dimetallic species 186a or 186b with CuCN led to a new organometallic species formulated as 191 which displayed remarkable thermal stability. Addition of reactive alkylating agents such as allyl bromide to 191 directly produced compound 192. Indeed, once the first alkylation occurred, the copper salts present in... 

Commercial wines are commonly tested for protein stability. Wine proteins, upon denaturation by heat or cold, may cause cloudiness and unsightly deposits after bottling. In addition, proteins may combine with iron and copper salts to form flocculate material in bottled wines. The reaction and absorption of proteins on bentonite is an effective means of removing protein from wines (109, 110, 111). Therefore, fining wines... 

ETFE degradation is autocatalytic and similar to that of PVDF and is accompanied by the evolution of HF. Iron and transition metal salts can accelerate the degradation of ETFE by dehydrofluorination and oligomer formation.10 Copper salts have been found to stabilize the polymer.11 ETFE decomposes rapidly at temperatures above 380°C (716°F).n... 

Electroless copper solutions contain copper salts and a reducing agent, such as formaldehyde the preparations for industrial use contain also stabilizers like 2-mercaptobenzothiazole, to prevent decomposition other than on activated areas of the workpiece, and accelerators like ethylenediamine-tetra-acetic acid—which increase the rate at which metal is deposited. Formulating such solutions requires achieving a balance between stability on the one hand and speedy deposition on the other. 

A different approach that even obviates the use of a preformed silyllithium reagent takes advantage of the cleavage of the Si-Si bond of a disilane by a copper salt. Hosomi and co-workers185 have reported on the reaction of various enones or enals 250 with hexamethyldisilane or l,l,2,2-tetramethyl-l,2-diphenyldisilane, catalyzed by copper(i) triflate-benzene complex (Scheme 61). The transformation requires heating to 80-100 °C in DMF or DMI and the presence of tri-/z-butylphosphine in order to stabilize the copper catalyst under these harsh conditions. The addition products 251 were obtained with high yield after acidic work-up. The application of the method to alkylidene malonates as the Michael acceptor was recently disclosed.1... 

While free nitrotetrazole is extremely sensitive and only of limited thermal stability, the salts of nitrotetrazole are, at least thermally, often significantly more stable. The best synthetic route starts from 5-aminotetrazole via the corresponding copper salt (M = alkali metal) ... 

Very little information is available concerning the thermal stability of the metallic salts of the acid carbonates and thiocarbonates. Calcium glyc-eritol dicarbonate [C3H60H(C0s )2Ca ], although very unstable in solution, could be stored at room temperature in an anhydrous state for a short period of time. On being strongly heated it charred, with the evolution of acrolein. A hydrated 0-(sodium thiocarbonyl) derivative of cellulose became insoluble in alkali within 24 hours at room temperature, due to decomposition. On the other hand, many metal xanthates, particularly the insoluble copper salts, which are readily obtained in a pure, anhydrous state, appear to be reasonably stable at about 20°. This very limited evi-... 

Polyvinylidene fluoride (PVDF) is considerably less thermally stable than PTFE but much more stable than polyvinyl fluoride (PVF) or polychlorotrifluoroethylene (PCTFE). Certain inorganic compounds (silica, titanium dioxide, and antimony oxide) can catalyze its decomposition at temperatures above 375°C (707°F) [10], ETFE degradation is autocatalytic and similar to that of PVDF and is accompanied by the evolution of hydrogen fluoride (HF). Iron and transition metal salts can accelerate the degradation of ETFE by dehydrofluorination and oligomer formation [10], Copper salts have been found to stabilize the polymer [11], ETFE decomposes rapidly at temperatures above 380°C (716°F) [11],... 

Copper salts have become crucial additives for bond forming reactions between carbon and heteroatoms such as N, O, S, or P. While many involve a transmetalation see Transmetalation) step from Pd, Ni, Sn, B, Te, Se, Mg, and so on, several of these cross-coupling see Coupling) reactions occur with copper as the only metal present. Typically, a (bidentate) ligand is used for stabilization of a copper-containing intermediate, while enhancing reactivity of the copper catalyst. 

Oxidative coupling was used for the synthesis of some stabilizers having properties of AO or FR. Products of oxidation of 4,4 -isopropylidenebis(2-methyl-6-tert-butylphenol with pota ium ferricyanide [151] or of 4,4 -thiobis(2-rcr/-butyl-5-methylphenol) with oxygen in the presence of copper salts [152] (118) were tested as AO. Thermostable fireproofing additives containing 1 to 4 bromine atoms on a phenolic moiety and designed for the stabilization of thermoplastics, e.g. 119, were prepared by oxidative coupling of brominated phenols [153]. 

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